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La Muerte lagoon is an ephemeral endorheic water body located in the Monegros desert, Zaragoza, Spain. Amplicon sequencing of the 16S rRNA gene was performed to analyze the bacterial and archaeal communities in biofilmsediment samples over three years, to understand the dynamic changes in the microbial community. PICRUSt and shotgun metagenomics were used to examine energy production and carbohydrate metabolism pathways. The dominant bacterial phyla were Actinobacteriota, Bacteroidota, Cyanobacteriota, and Pseudomonadota, while Halobacteriota was the predominant archaeal phylum. Despite seasonal environmental fluctuations, the biofilm community remained stable over time, suggesting resilience. The Calvin-Benson cycle was the main carbon fixation pathway, carried out by Cyanobacteria and purple non-sulfur bacteria. Nitrogen fixation by diazotrophs supplied an important nitrogen source. Organic carbon was derived primarily from autotrophs, with little use of allochthonous plant material. The comparison of biofilm-sediment and water column biotopes showed distinct but related prokaryote communities. Biofilm-sediments showed higher taxonomic diversity and different proportions of microbial phyla compared to the water column. This study provides initial insights into the complex microbial life in endorheic lagoons and underscores the importance of protecting these globally threatened habitats. The limited sample size in this study warrants further investigation with a more comprehensive sampling strategy to fully characterize the microbial communities and their functional roles in the different biotopes of La Muerte lagoon. [ABSTRACT FROM AUTHOR]

The Gypsum Karst of Sorbas, Almeria, southeast Spain, includes a few caves whose entrances are open and allow the entry and roosting of numerous bats. Caves are characterized by their diversity of gypsum speleothems, such as stalactites, coralloids, gypsum crusts, etc. Colored biofilms can be observed on the walls of most caves, among which the Covadura and C3 caves were studied. The objective was to determine the influence that bat mycobiomes may have on the fungal communities of biofilms. The results indicate that the fungi retrieved from white and yellow biofilms in Covadura Cave (Ascomycota, Mortierellomycota, Basidiomycota) showed a wide diversity, depending on their location, and were highly influenced by the bat population, the guano and the arthropods that thrive in the guano, while C3 Cave was more strongly influenced by soil- and arthropod-related fungi (Ascomycota, Mortierellomycota), due to the absence of roosting bats. [ABSTRACT FROM AUTHOR]

Objectives: To test a hypothesis on interpersonal violence events during the transition between Chalcolithic and Bronze Age in the Eastern Pyrenees, to contextualize it in Western Europe during that period, and to assess if these marks can be differentiated from secondary funerary treatment. Materials and Methods: Metric and non‐metric methods were used to estimate the age‐at‐death and sex of the skeletal remains. Perimortem injuries were observed and analyzed with stereomicroscopy and confocal microscopy. Results: Among the minimum of 51 individuals documented, at least six people showed evidence of perimortem trauma. All age groups and both sexes are represented in the skeletal sample, but those with violent injuries are predominantly males. Twenty‐six bones had 49 injuries, 48 of which involved sharp force trauma on postcranial elements, and one example of blunt force trauma on a cranium. The wounds were mostly located on the upper extremities and ribs, anterior and posterior. Several antemortem lesions were also documented in the assemblage. Discussion: The perimortem lesions, together with direct dating, suggest that more than one episode of interpersonal violence took place between the Late Chalcolithic and the Early Bronze Age in northeastern Spain. The features of the sharp force trauma indicate that different weapons were used, including sharp metal objects and lithic projectiles. The Roc de les Orenetes assemblage represents a scenario of recurrent lethal confrontation in a high mountain geographic context, representing the evidence of inferred interpersonal violence located at the highest altitude settings in the Pyrenees, at 1836 meters above sea level. [ABSTRACT FROM AUTHOR]

Background: Infections by the pathogen Staphylococcus aureus currently represent one of the most serious threats to human health worldwide, especially due to the production of enterotoxins and the ability to form biofilms. These structures and the acquisition of antibiotic resistance limit the action of antibiotics and disinfectants used to combat this microorganism in the industry and the clinic. Methods: This work reports a comparative phenotypic and genotypic study of 18 S. aureus strains from different origins: clinical samples, milk from mastitic cows and food industry surfaces, most of which were isolated in Northern Spain. Results: Genetically, the strains were very diverse but, in most cases, a closer proximity was observed for those from the same source. Notably, the average number of virulence genes was not significantly different in strains from the food sector. Of the 18 strains, 10 coded for at least one enterotoxin, and four of them carried 6 or 7 enterotoxin genes. The latter were all veterinary or clinical isolates. Most strains carried prophages, plasmids and/or pathogenicity islands. Regarding antibiotic resistance, although phenotypically all strains showed resistance to at least one antibiotic, resistance genes were only identified in 44.5% of strains, being mastitis isolates those with the lowest prevalence. Virulence-related phenotypic properties such as haemolytic activity, staphyloxanthin production, biofilm-forming capacity and spreading ability were widely distributed amongst the isolates. Conclusions: Our results indicate that production of virulence factors, antibiotic resistance and biofilm formation can be found in S. aureus isolates from diverse environments, including the food industry, although some of these traits are more prevalent in strains isolated from infections in cows or humans. This emphasizes on the importance of monitoring the spread of these determinants not only in samples from the clinical environment, but also along the food chain, a strategy that falls under the prism of a one-health approach. [ABSTRACT FROM AUTHOR]

Show caves have different grades of colonization by phototrophic biofilms. They may receive a varied number of visits, from a few thousand to hundreds of thousands of visitors annually. Among them, Tesoro Cave, Rincon de la Victoria, Spain, showed severe anthropic alterations, including artificial lighting. The most noticeable effect of the lighting was the growth of a dense phototrophic community of cyanobacteria, algae and bryophytes on the speleothems, walls and ground. The biofilms were dominated by the cyanobacterium Phormidium sp., the chlorophyte Myrmecia israelensis, and the rhodophyte Cyanidium sp. In many cases, the biofilms also showed an abundance of the bryophyte Eucladium verticillatum. Other cyanobacteria observed in different biofilms along the cave were: Chroococcidiopsis sp., Synechocystis sp. and Nostoc cf. edaphicum, the green microalgae Pseudococcomyxa simplex, Chlorella sp. and the diatom Diadesmis contenta. Preliminary cleaning tests on selected areas showed the effectiveness of hydrogen peroxide and sodium hypochlorite. A physicochemical treatment involving the mechanical removal of the thickest layers of biofilms was followed by chemical treatments. In total, 94% of the surface was cleaned with hydrogen peroxide, with a subsequent treatment with sodium hypochlorite in only 1% of cases. The remaining 5% was cleaned with sodium hypochlorite in areas where the biofilms were entrapped into a calcite layer and in sandy surfaces with little physical compaction. The green biofilms from the entire cave were successfully cleaned. [ABSTRACT FROM AUTHOR]

Flor yeast velum is a biofilm formed by certain yeast strains that distinguishes biologically aged wines such as Sherry wine from southern Spain from others. Although Saccharomyces cerevisiae is the most common species, 5.8 S-internal transcribed spacer (ITS) restriction fragment length polymorphism analyses have revealed the existence of non- Saccharomyces species. In order to uncover the flor microbiota diversity at a species level, we used ITS (internal transcribed spacer 1)-metabarcoding and matrix-assisted laser desorption/Ionization time of flight mass spectrometry techniques. Further, to enhance identification effectiveness, we performed an additional incubation stage in 1:1 wine:yeast extract peptone dextrose (YPD) before identification. Six species were identified: S. cerevisiae , Pichia manshurica , Pichia membranifaciens , Wickerhamomyces anomalus , Candida guillermondii , and Trichosporon asahii , two of which were discovered for the first time (C. guillermondii and Trichosporon ashaii) in Sherry wines. We analyzed wines where non- Saccharomyces yeasts were present or absent to see any potential link between the microbiota and the chemical profile. Only 2 significant volatile chemicals (out of 13 quantified), ethanol and ethyl lactate, and 2 enological parameters (out of 6 quantified), such as pH and titratable acidity, were found to differ in long-aged wines. Although results show a low impact where the non- Saccharomyces yeasts are present, these yeasts isolated from harsh environments (high ethanol and low nutrient availability) could have a potential industrial interest in fields such as food microbiology and biofuel production. [ABSTRACT FROM AUTHOR]

This study delved into the evolution of fungal population during the fermentation of Spanish-style green table olives (Manzanilla cultivar), determining the influence of different factors such as fermentation matrix (brine or fruit) or the use of a lactic acid bacteria inoculum, on its distribution. The samples (n = 24) were directly obtained from industrial fermentation vessels with approximately 10.000 kg of fruits and 6.000 L of brines. Our findings showcased a synchronized uptick in lactic acid bacteria counts alongside fungi proliferation. Metataxonomic analysis of the Internal Transcribed Spacer (ITS) region unearthed noteworthy disparities across different fermentation time points (0, 24, and 83 days). Statistical analysis pinpointed two Amplicon Sequence Variants (ASV), Candida and Aureobasidium, as accountable for the observed variances among the different fermentation time samples. Notably, Candida exhibited a marked increase during 83 days of fermentation, opposite to Aureobasidium, which demonstrated a decline. Fungal biodiversity was slightly higher in brines than in fruits, whilst no effect of inoculation was noticed. At the onset of fermentation, prominently detected genera were also Mycosphaerella (19.82 %) and Apohysomyces (16.31 %), hitherto unreported in the context of table olive processing. However, their prevalence dwindled to nearly negligible levels from 24th day fermentation onwards (<2 %). On the contrary, they were replaced by the fermentative yeasts Saccharomyces and Isstachenkia. Results obtained in this work will be useful for designing new strategies for better control of table olive fermentations., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest regarding the publication of this article., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Local granite has been used throughout history in Galicia (NW Spain), forming the basis of much of the region's architecture. Like any other rock, granite provides an ecological niche for a multitude of organisms that form biofilms that can affect the physical integrity of the stone. In this study, for the first time, characterization of the microbial consortium forming biofilms that developed on historical rural granite buildings is carried out using a combination of culture-dependent and next generation sequencing (NGS) techniques. Results pointed to differences in biofilm composition on the studied rural granite buildings and that of previously analyzed urban granite buildings, especially in terms of abundance of cyanobacteria and lichenized fungi. Exposure was corroborated as an important factor, controlling both the diversity and abundance of microorganisms on walls, with environmental factors associated with a northern orientation favoring a higher diversity of fungi and green algae, and environmental factors associated with the west orientation determining the abundance of lichenized fungi. The orientation also affected the distribution of green algae, with one of the two most abundant species, Trentepohlia cf. umbrina, colonizing north-facing walls, while the other, Desmococcus olivaceus, predominated on west-facing walls. [ABSTRACT FROM AUTHOR]

Streptococcus pneumoniae is the main bacterial cause of respiratory infections in children and the elderly worldwide. Serotype replacement is a frequent phenomenon after the introduction of conjugated vaccines, with emerging serotypes 22F and 33F as frequent non-PCV13 serotypes in children and adults in North America and other countries. Characterization of mechanisms involved in evasion of the host immune response by these serotypes is of great importance in public health because they are included in the future conjugated vaccines PCV15 and PCV20. One of the main strategies of S. pneumoniae to persistently colonize and causes infection is biofilm formation. In this study, we have evaluated the influence of capsule polysaccharide in biofilm formation and immune evasion by using clinical isolates from different sources and isogenic strains with capsules from prevalent serotypes. Since the introduction of PCV13 in Spain in the year 2010, isolates of serotypes 22F and 33F are rising among risk populations. The predominant circulating genotypes are ST43322 F and ST71733 F , being CC433 in 22F and CC717 in 33F the main clonal complexes in Spain. The use of clinical isolates of different origin, demonstrated that pediatric isolates of serotypes 22F and 33F formed better biofilms than adult isolates and this was statistically significant. This phenotype was greater in clinical isolates from blood origin compared to those from cerebrospinal fluid, pleural fluid and otitis. Opsonophagocytosis assays showed that serotype 22F and 33F were recognized by the PSGL-1 receptor on leukocytes, although serotype 22F, was more resistant than serotype 33F to phagocytosis killing and more lethal in a mouse sepsis model. Overall, the emergence of additional PCV15 serotypes, especially 22F, could be associated to an enhanced ability to divert the host immune response that markedly increased in a biofilm state. Our findings demonstrate that pediatric isolates of 22F and 33F, that form better biofilm than isolates from adults, could have an advantage to colonize the nasopharynx of children and therefore, be important in carriage and subsequent dissemination to the elderly. The increased ability of serotype 22F to avoid the host immune response, might explain the emergence of this serotype in the last years. [ABSTRACT FROM AUTHOR]

Hydro-morphological alterations in water bodies caused by climate change and human activities affects the ecosystem functioning and generate important water quality problems. Some of these alterations can generate an increase in cyanobacterial blooms, which are associated with the appearance of bad taste and odorous compounds such as geosmin. The factors that trigger their production are still unclear, and this inability to predict geosmin episodes provokes economic problems for water supply companies. This study aims to evaluate the effects of water flow and light availability on biofilm development and intracellular geosmin formation. A mesocosm experiment was performed between February–April, 2019. The mesocosms were a set of 10 outdoor 3 m long flumes, with a continuous water supply from the Ter river (Catalonia, NE Spain). Two light intensities were established: natural light and light reduced to 80%, combined with five gradual water flows from 0.09 to 1.10 L/s. Water samples were taken to analyze nutrients, and biofilm samples, to analyze geosmin concentration, chlorophyll a and the community. Geosmin in biofilm was detected in those treatments in which Oscillatoria sp. appeared. The concentration of intracellular geosmin was higher at lower water flows (0.09 and 0.18 L/s), and the highest (2.12 mg/g) was found in the flume with the lowest water flow (0.09 L/s) and irradiation (20%). This flume was the one that presented a greater concentration of Oscillatoria sp. (21% of the community). It stands out that, when geosmin in biofilm was found, the dissolved inorganic nitrogen and soluble reactive phosphorus ratio decreased, from an average of 417:1 to 14:1. This was mainly due to an increase in inorganic phosphorus concentration generated by a change in the nutrient uptake capacity of the community's biofilm. The results obtained in this study indicated the potential implications for stream ecosystem management to control geosmin appearance. Likewise, they could be used as an early warning system, establishing that in times of drought, which lead to a general decrease in river water flow, the situation could be optimal for the appearance and development of geosmin producing cyanobacteria in low-flow areas near the river banks. [ABSTRACT FROM AUTHOR]

Summary: Microbial communities in natural ecosystems are subject to strong ecological rules. The study of local communities along a regional metacommunity can reveal patterns of community assembly, and disentangle the underlying ecological processes. In particular, we seek drivers of community assembly at the regional scale using a large lacustrine dataset (>300 lakes) along the geographical, limnological and physico‐chemical gradients in the Pyrenees. By using high throughput amplicon sequencing of the 16S rRNA gene, and inferring environmental sources of bacterial immigrants, we showed that surface aquatic bacterial assemblages were strongly influenced by terrestrial populations from soil, biofilms or sediments, and primarily selected by a pH‐alkalinity gradient. Indeed, source proportions explained 27% of the community variation, and chemistry 15% of the total variation, half of it shared with the sources. Major taxonomic groups such as Verrucomicrobia, Actinobacteria and Bacteroidetes showed higher aquatic affinities than Parcubacteria, Gammaproteobacteria, Alphaproteobacteria or Betaproteobacteria, which may be recruited and selected through different hydrographic habitats. A regional fingerprint was observed with lower alpha diversity and higher beta diversity in the central Pyrenees than in both ends. We suggest an ecological succession process, likely influenced by complex interactions of environmental source dispersal and environmental filtering along the mountain range geography. [ABSTRACT FROM AUTHOR]

Sherry wines are film wines produced in the Jerez-Xérès-Sherry and Montilla-Moriles regions in southern Spain which require an aging process under flor biofilms, known as "biological aging". The presence of mites in Sherry wine wineries has been reported and associated with improved wine volatile properties. This work analyzes the microbial diversity in flor biofilms and mites in Sherry wine wineries using Matrix-Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) and ITS/gene amplification. Two mite species, Carpoglyphus lactis and Tyrophagus putrescentiae , were spotted in the sampled winery and 32 microorganism species were identified in their exoskeleton or surrounding biofilms. To our knowledge, 26 of these species were never described before in sherry wine environments. We hypothesized that mites feed on the flor biofilms as well as another type of biofilm located in barrel cracks, known by winemakers as "natas" (cream in English). These non-studied biofilms showed the highest microbiome diversity among all samples (followed by C. lactis spotted nearby) thus, representing a niche of microorganisms with potential biotechnological interest. Besides mites, Drosophila flies were spotted in the sampling areas. The role of flies and mites as vectors that transport microorganisms among different niches (i.e., flor biofilms and natas) is discussed. • 32 microorganism species were identified, 26 not described before in Sherry wineries. • "Natas" biofilm formed by multiple microorganisms, is described for the first time. • Mites may act as microorganism vectors between different winery environments. [ABSTRACT FROM AUTHOR]

Cave heritage is often threatened by tourism or even scientific activities, which can lead to irreversible deterioration. We present a preventive conservation monitoring protocol to protect caves with rock art, focusing on La Garma Cave (Spain), a World Heritage Site with valuable archaeological materials and Palaeolithic paintings. This study assessed the suitability of the cave for tourist use through continuous microclimate and airborne particles monitoring, biofilm analysis, aerobiological monitoring and experimental visits. Our findings indicate several factors that make it inadvisable to adapt the cave for tourist use. Human presence and transit within the cave cause cumulative effects on the temperature of environmentally very stable and fragile sectors and significant resuspension of particles from the cave sediments. These environmental perturbations represent severe impacts as they affect the natural aerodynamic control of airborne particles and determine bacterial dispersal throughout the cave. This monitoring protocol provides part of the evidence to design strategies for sustainable cave management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In the absence of sunlight, caves harbor a great diversity of microbial colonies to extensive biofilms with different sizes and colors visible to the naked eye. One of the most widespread and visible types of biofilm are those with yellow hues that can constitute a serious problem for the conservation of cultural heritage in many caves, such as Pindal Cave (Asturias, Spain). This cave, declared a World Heritage Site by UNESCO for its Paleolithic parietal art, shows a high degree of development of yellow biofilms that represents a real threat to the conservation of painted and engraved figures. This study aims to: 1) identify the microbial structures and the most characteristic taxa composing the yellow biofilms, 2) seek the linked microbiome reservoir primarily contributing to their growth; 3) seed light on the driving vectors that contribute to their formation and determine the subsequent proliferation and spatial distribution. To achieve this goal, we used amplicon-based massive sequencing, in combination with other techniques such as microscopy, in situ hybridization and environmental monitoring, to compare the microbial communities of yellow biofilms with those of drip waters, cave sediments and exterior soil. The results revealed microbial structures related to the phylum Actinomycetota and the most characteristic bacteria in yellow biofilms, represented by the genera wb1-P19, Crossiella, Nitrospira, and Arenimonas. Our findings suggest that sediments serve as potential reservoirs and colonization sites for these bacteria that can develop into biofilms under favorable environmental and substrate conditions, with a particular affinity for speleothems and rugged-surfaced rocks found in condensation-prone areas. This study presents an exhaustive study of microbial communities of yellow biofilms in a cave, which could be used as a procedure for the identification of similar biofilms in other caves and to design effective conservation strategies in caves with valuable cultural heritage., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Objectives To relate five periodontopathogenic bacteria, including the red complex, to the severity, extent, and inflammation of the periodontal lesion in Caucasian patients with generalized aggressive and chronic periodontitis and to explore whether tobacco use is associated with a specific bacterial profile. Materials and Methods A cross-sectional and analytic study was conducted in patients with aggressive and chronic periodontitis. Data were gathered on socio-demographic and periodontal variables, and RH- PCR was used to determine subgingival bacterial profile. Linear and logistic regression analyses were performed. Results The study included 60 patients with aggressive and 123 with chronic periodontitis. Total red complex bacteria count was higher in aggressive periodontitis, mainly due to T. denticola ( P = 0.015). In both periodontitis types, models showed an association between T. forsythia count and probing depth (B = 0.157, P = 0.030) and between T. denticola count and higher bleeding scores (B = 2.371, P = 0.027). Smoking did not affect the red complex bacteria count in either disease. Conclusions The prevalence of red complex bacteria was similar between aggressive and chronic periodontitis, but their count was higher in the former. In both diseases, T. forsythia was associated with greater severity and T. denticola with more severe bleeding. Tobacco smoking was not associated with the presence of red complex bacteria in either disease. [ABSTRACT FROM AUTHOR]

Numerous designs of punctal and canalicular plugs are available on the market. This variety presents challenges to ophthalmologists when choosing punctal plugs for the management of various ocular conditions. The aim of this literature review is to provide a classification system for lacrimal occlusive devices based on their location and duration of action as well as to identify different characteristics of each one of them. We want to give a comprehensive overview on punctal and canalicular plugs including their manufacturing companies, indications, and complications that have been reported in various articles. PubMed and Google Scholar were used to identify articles written in English as well as few articles written in Japanese, Chinese, Slovak, and Spanish that had abstracts in English. Nine different companies that manufacture punctal and canalicular plugs were identified and their plugs were included in this review. Punctal and canalicular plugs are used in the management of various ocular conditions including dry eye disease and punctal stenosis as well as in ocular drug delivery. Although they are a relatively safe option, associated complications have been reported in the literature such as infection, allergic reaction, extrusion, and migration. [ABSTRACT FROM AUTHOR]

Background and Objective Bacteria in the oral cavity grow in the form of biofilms; these structures are subject to constant saliva or gingival crevicular fluid flow conditions. The aims of this study were: (i) to develop and to characterize an in-vitro biofilm model with oral bacteria growing under flow and shear conditions; and (ii) to demonstrate the usefulness of the model for evaluating the activity of three antiplaque agents. Material and Methods We used a bioreactor to grow the oral bacteria Streptococcus oralis, Actinomyces naeslundii, Veillonella parvula, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis under planktonic conditions. Biofilms were established using a modified Robbins device on hydroxyapatite ( HAP) discs. Three- to 7-d-old biofilms were analysed using culture methods, scanning electron microscopy, Live/ Dead staining and fluorescence in-situ hybridization (confocal laser scanning microscopy). Finally, we assessed the antimicrobial activity of three mouthrinses [0.12% chlorhexidine ( CHX), 0.12% chlorhexidine and sodium fluoride ( CHX+ Na F) and 0.12% chlorhexidine and 0.05% cetylpyridinium chloride ( CHX+ CPC)] using a planktonic test (short interval-killing test) and in our 4-d biofilm model. Results The viable cell counts showed that each species was consistently found in the biofilms throughout the study. The architecture and cell distribution were similar to those described for biofilms in situ, with the exception of a thin layer of living cells that was found close to the HAP. The effectiveness test of the mouthwashes demonstrated that cells in biofilms showed more tolerance compared with planktonic cells. Moreover, it was observed that in 4-d biofilm formed in vitro, CHX+ CPC caused significantly higher mortality compared with CHX ( p = 0.003) and CHX+ Na F ( p < 0.001). Conclusion Our results suggest that we have a highly reproducible system for multispecies oral biofilm formation and that it is a useful tool for assessing antibacterial molecules before their clinical evaluation. It also has great potential to be used in basic research on supragingival and subgingival biofilms. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA) may persist for long periods due to biofilm formation. The objective of this study was to describe biofilm formation in association with the presence of S. aureus surface protein G (sasG) and its allelic variants in MRSA bacteraemia isolates from endemic (CC5, CC8, CC22) and sporadic clones in Spain (2008–2015). Crystal violet staining was used to assess biofilm formation; DNA microarray, RT-qPCR, and long-read whole genome sequencing were applied to determine the presence, expression and structure of sasG , respectively. The endemic CC5 and CC8 clones produced more biofilm than the sporadic clones; these endemic clones carried sasG allelic variant 1. Otherwise, sporadic clones, with less biofilm formation, showed either an absence of sasG (65%) or the presence of allelic variant 2 (35%). Variants 1 and 2 differed in the expression of sasG (1.56 ± 1.20 and 0.37 ± 0.32, respectively). The analysis of a large cohort of closed S. aureus genomes available on the NCBI database confirmed the distribution of the two allelic variants with low amino acid identity (68.1%) among endemic and sporadic clones. SasG variant 1 present in the major CC5 and CC8 clones was correlated with increased biofilm formation and may represent an important virulence determinant. [ABSTRACT FROM AUTHOR]

The occurrence and environmental factors responsible for the distribution of benthic cyanobacteria in running waters remain largely unexplored in comparison with those of other aquatic ecosystems. In this study, combined data of ecological characteristics, molecular analysis (based on 16S rRNA gene), and direct microscopic inspection of environmental samples were analyzed in parallel with the morphological characterization of the isolated strains to investigate benthic cyanobacterial diversity in the Guadarrama river ( Spain). A total of 17 species were identified that belonged to the genera Aphanocapsa, Pleurocapsa, Chroococcus, Chamaesiphon, Cyanobium, Pseudan-abaena, Leptolyngbya, Phormidium, Nostoc, and Tolypothrix. Phenotypic features were associated with the results of 16S rRNA gene sequencing, complementing existing morphological and genetic databases. A decrease in the cyanobacterial diversity was observed along a pollution gradient in the river. Water quality differed among the sampling sites, and variation in nutrient content was the principal difference among locations. These characteristics were closely associated with an upstream-downstream eutrophic gradient. Canonical correspondence analysis distinguished three groups of species with respect to the eutrophication gradient. The first group ( Tolypothrix cf. tenuis, Nostoc punctiforme, Nostoc piscinale, Chamaesiphon investiens, Chroococcus minor, Leptolyngbya nostocorum, and Leptolyngbya tenuis) was characteristic of waters with low levels of nutrients. The second group ( Cyanobium sp ., Chamaesiphon polymorphus, Leptolyngbya boryana, Phormidium autumnale, Phormidium sp., and Aphanocapsa cf. rivularis) was characteristic of polluted waters, its members appearing mainly in great abundance under eutrophic-hypertrophic conditions. The third group of species ( Pseudanabaena catenata, Aphanocapsa muscicola, and Nostoc carneum) was present at upstream and downstream sites. [ABSTRACT FROM AUTHOR]

The occurrence and environmental factors responsible for the distribution of benthic cyanobacteria in running waters remain largely unexplored in comparison with those of other aquatic ecosystems. In this study, combined data of ecological characteristics, molecular analysis (based on 16S rRNA gene), and direct microscopic inspection of environmental samples were analyzed in parallel with the morphological characterization of the isolated strains to investigate benthic cyanobacterial diversity in the Guadarrama river ( Spain). A total of 17 species were identified that belonged to the genera Aphanocapsa, Pleurocapsa, Chroococcus, Chamaesiphon, Cyanobium, Pseudan-abaena, Leptolyngbya, Phormidium, Nostoc, and Tolypothrix. Phenotypic features were associated with the results of 16S rRNA gene sequencing, complementing existing morphological and genetic databases. A decrease in the cyanobacterial diversity was observed along a pollution gradient in the river. Water quality differed among the sampling sites, and variation in nutrient content was the principal difference among locations. These characteristics were closely associated with an upstream-downstream eutrophic gradient. Canonical correspondence analysis distinguished three groups of species with respect to the eutrophication gradient. The first group ( Tolypothrix cf. tenuis, Nostoc punctiforme, Nostoc piscinale, Chamaesiphon investiens, Chroococcus minor, Leptolyngbya nostocorum, and Leptolyngbya tenuis) was characteristic of waters with low levels of nutrients. The second group ( Cyanobium sp ., Chamaesiphon polymorphus, Leptolyngbya boryana, Phormidium autumnale, Phormidium sp., and Aphanocapsa cf. rivularis) was characteristic of polluted waters, its members appearing mainly in great abundance under eutrophic-hypertrophic conditions. The third group of species ( Pseudanabaena catenata, Aphanocapsa muscicola, and Nostoc carneum) was present at upstream and downstream sites. [ABSTRACT FROM AUTHOR]

An advanced treatment for wastewater reclamation has been studied for nine months in a pilot plant in the south of Spain. This consisted in a combination of integrated fixed-film activated sludge (IFAS) and membrane bioreactor (MBR) technology (called here IFAS-MBR) with posterior reverse osmosis (RO) for the achievement of a high-quality effluent. The pilot plant was obtained from a former MBR plant, where plastic carriers for the support of the biology were introduced in the second aerobic chamber. The system consisted of two parallel lines, one working with a hollow fibre module and the other with a flat sheet module. After the hollow fibre line, an RO system treated the effluent. The permeability of the process decreased gradually along the experimentation period and after six months, the membrane modules of both lines were chemically cleaned. The RO membranes showed a stable permeability working with the IFAS-MBR permeate and chemically cleaned after four months of operation. The studied system combined the advantages of both IFAS and MBR technologies and it is an interesting choice when the footprint is limited or a high effluent quality is required and it is an attractive pretreatment for reverse osmosis systems. [ABSTRACT FROM AUTHOR]

Introduction: Concentrations of alkylphenolic compounds (APCs) in water and sediments were related to the composition and functional descriptors of the benthic community (biofilm and macroinvertebrates). Materials and methods: Samples were collected in four sampling campaigns at seven sampling points in the lower Llobregat catchment area (NE Spain). Water and sediment samples underwent chemical target analysis for nine APCs, which are known to disrupt the endocrine system. Results and discussions: APCs were the main stressors on the diatom community but not on the macroinvertebrate community. Conclusions: Benthic invertebrates were mostly affected by the general physicochemical water characteristics (where conductivity was a surrogate). Nonylphenol only had an influence on the diatom community in water but not in the remaining compartments, probably because of the low concentrations observed in the environment. [ABSTRACT FROM AUTHOR]

Abstract: Multi-storey calcrete profiles developed in the Quaternary on strath terraces of the Cinca and Alcanadre rivers, tributaries of the Ebro River in NE Spain. Two calcrete profiles (Tor 1 and Tor 2) near the village of El Tormillo show horizons with an arrangement that differs from that of commonly described calcrete profiles. Significant lateral changes occur in these profiles within a distance of less than 200m, reflecting their pedofacies relationship. The Tor 1 profile on terrace Qt1 (the highest and oldest) consists of six horizons (from bottom to top): 1) coarse fluvial gravels; 2) mudstones with carbonate nodules; 3) a chalky horizon; 4) laminar horizons, including one peloidal horizon; 5) a multi-storey horizon formed of at least six minor sequences, each of which includes a lower detrital layer, a pisolithic horizon, and a thin discontinuous laminar horizon (these sequences indicate several cycles of brecciation and/or reworking); and 6) a topmost laminar and brecciated horizon also including reworked pisoliths. Some 200m to the north of Tor 1, horizon 5 undergoes a lateral change to channel fill-deposits. The infill of the channels shows a fining-upwards sequence ranging from clasts of about 10cm in diameter to red silts with sparse pebbles. All the clasts come from the underlying calcrete horizons. Laminar horizons are interbedded with the clastic channel deposits. The youngest calcrete profiles developed on terrace Qt3 of the Cinca River and on the Qp4 and Qp6 mantled pediment levels. All show relatively simple profiles composed mostly of lower horizons of coated gravels, with thin laminar horizons at the top. Most of the horizons, especially the laminar ones, show biogenic features such as alveolar septal structures, calcified filaments, biofilms, spherulites, micropores and needle-like calcite crystals. These features indicate the important role of vegetation in the formation of all the above profiles. The interbedding of clastic sediments and pisolithic horizons within the Tor 2 profile indicates several stages of stabilisation during profile formation. These sequences are an indication of the sedimentation, soil formation and reworking processes operating on the soil surface. The alternation of these processes is interpreted as the result of climate–vegetation changes. The channel-fills of Tor 2 indicate erosion and reworking of the hard laminar calcrete horizon. Both Tor 1 and Tor 2 are multi-storey profiles reflecting the complex sedimentation–erosion–pedogenesis relationships at the final stages of the development of its corresponding fluvial terrace. The study of these calcretes shows that these supposedly abandoned terraces continue to be active even though the fluvial network is entrenched. Both the pedofacies relationships and the complexity shown by Tor 1 and Tor 2 reflect the complex and unstable geomorphic setting in which these profiles developed. After the establishment of the exorrheic network, less complex calcrete profiles were produced in the lower terraces. [Copyright &y& Elsevier]

Marine biofilms were established on glass beads with or without deliberate pre-exposure to LAS (20μg/L) in Spain (Cadiz) and Sweden (Kristineberg). The ability of each community to mineralize LAS (100μg/L) was then assessed in biometers at four experimental temperatures (between 6 and 21°C). Genetic diversity and biomass of the biofilms were assessed by genetic fingerprinting (DGGE) and direct bacterial counts. With biofilms from Sweden, where LAS was not detected in seawater (n=3), deliberate pre-exposure to LAS resulted in lower genetic diversity and higher mineralization rate constant; however, with biofilms from Spain, where 6.4±3.9μgLAS/L (n=3) was measured during the colonization, pre-exposure did not affect the bacterial community. Bacterial acclimation therefore appeared to have been induced at environmental concentrations <6μgLAS/L. Environmental pre-exposure was not a pre-requisite for featuring the full consortia of LAS degraders in the biometers. The mineralization rate was described using an Arrhenius equation at experimental temperatures within the typical annual range; however, they departed from this model below this range. [Copyright &y& Elsevier]

Objectives To study the incidence of rifampicin-resistant Staphylococcus aureus in Gipuzkoa, Northern Spain, and to characterize representative resistant isolates and mutations associated with resistance. Methods For rifampicin-resistant isolates, the rpoB gene fragment that includes the most frequent mutations conferring rifampicin resistance in S. aureus was amplified and sequenced. The role of new mutations responsible for rifampicin resistance was confirmed by cloning and complementation in trans. Resistant isolates were characterized by multilocus sequence typing and PFGE. Results Between 1999 and 2008, 0.59% (96/16 348) of S. aureus clinical isolates studied showed rifampicin resistance. Rifampicin resistance was higher in methicillin-resistant S. aureus (MRSA) than in methicillin-susceptible S. aureus (MSSA) (3.26% versus 0.26%; P < 0.001). Twenty-two randomly selected rifampicin-resistant isolates were studied in depth, 11 showing low-level and 11 showing high-level rifampicin resistance (rifampicin MICs of 2–4 mg/L and ≥8 mg/L, respectively). Overall, 12 different mutations in the rpoB gene were detected, including a newly described N474K mutation followed by the insertion of a glycine residue at position 475. Among the eight different sequence types (STs) found, the most frequent were ST8 and ST863, the latter being associated with respiratory infections. Ten of the 11 low-level rifampicin-resistant isolates were MRSA ST8 and had the same H481N mutation, while the 11 high-level rifampicin-resistant isolates, 6 MSSA and 5 MRSA, belonged to eight different STs and had distinct rpoB mutations. Conclusions Low-level rifampicin-resistant isolates were mainly clonal while high-level resistant isolates showed a high genetic diversity. Most mutations observed coincided with those found in other studies, but a new mutation conferring rifampicin resistance was detected. [ABSTRACT FROM PUBLISHER]

Candida parapsilosis former groups II and III have recently been established as independent species, named Candida orthopsilosis and Candida metapsilosis, respectively. We investigated the distribution of C. parapsilosis complex species in 122 isolates from blood and other sources in a southern Spain tertiary-care hospital, and we examined the relationship between species, site of isolation and biofilm positivity. We also evaluated the planktonic MICs and sessile MICs (SMICs) of voriconazole, amphotericin B and anidulafungin. One hundred and eleven isolates (91%) were categorized as C. parapsilosis sensu stricto, whereas ten isolates (8.2%) were categorized as C. orthopsilosis and one (0.8%) as C. metapsilosis. Biofilm positivity was observed in 58.5% (65 of 111) of C. parapsilosis sensu stricto isolates vs. 0% (0 of 11) of C. orthopsilosis and C. metapsilosis isolates (p <0.01). There was no difference in biofilm production among C. parapsilosis sensu stricto isolates from blood and other sources. MIC values showed that all isolates were susceptible to voriconazole and amphotericin B, whereas two isolates (1.8%) of C. parapsilosis sensu stricto were non-susceptible to anidulafungin. However, the MIC90 value of voriconazole was higher (0.125 mg/L) for C. orthopsilosis than for C. parapsilosis sensu stricto (0.03 mg/L). In contrast to planktonic cells, the SMICs show that amphotericin B and anidulafungin are moderately effective against the biofilm of C. parapsilosis sensu stricto, whereas voriconazole is ineffective. [ABSTRACT FROM AUTHOR]

This study examines fossil microorganisms found in iron-rich deposits in an extreme acidic environment, the Tinto River in SW Spain. Both electron microscopy (SEM and TEM) and non-destructive in situ microanalytical techniques (EDS, EMP and XPS) were used to determine the role of permineralization and encrustation in preserving microorganisms forming biofilms in the sediments. Unicellular algae were preserved by silica permineralization of their cell walls. Bacterial biofilms were preserved as molds by epicellular deposition of schwertmannite around them. In the case of fungi and filamentous algae, we observed permineralization of cell structures by schwertmannite in the sediments. The extracellular polymeric matrix around the cells was also preserved through permineralization of the fibrillar component. The process of permineralization and deposition of iron-rich precipitates present in the acidic waters of Rio Tinto served to preserve many microfossils in an oxidizing environment, in which organic compounds would not normally be expected to persist. Studies of microbial fossil formation mechanisms in modern extreme environments should focus on defining criteria to identify inorganic traces of microbial life in past environments on Earth or other planets. [ABSTRACT FROM AUTHOR]

In an attempt to study the diversity and persistence of molecular subtypes of pathogenic Listeria spp. in a cheese factory at the La Mancha region of Spain, 43 samples were taken from incoming raw milk (cow’s, ewe’s, goat’s and mixed species) and from certain food-contact and environmental surfaces before and/or after sanitation. Of these samples, 12 contained pathogenic Listeria. From the chromogenic agar plates corresponding to those, 46 phosphatidylinositol-specific phospholipase C-positive isolates were randomly taken for further analysis, including biochemical tests and pulsed-field gel electrophoresis (PFGE). They coincided in identifying all the 46 as Listeria ivanovii subsp. ivanovii, apparently a single PFGE type. Both ewe’s and goat’s raw milk batches from asymptomatic animals tested along the 6-month period persistently carried the same strain, which was also obtained from inner surfaces of raw milk truck tanks and the milk dump tank at the cheese factory. Biofilm-forming abilities of this L. ivanovii clone and interference against L. monocytogenes Scott A reference strain were tested, but failed to account for the clone’s apparent pervasive presence. [ABSTRACT FROM AUTHOR]

The biological colonization of rocks in the Cave of Bats (Cueva de Los Murciélagos, Zuheros, Spain) was studied in order to reveal the diversity of microorganisms involved in the biofilm formation. The culturable, metabolically active fraction of biodeteriogens present on surfaces was investigated focusing on morphological, ultrastructural, and genetic features, and their presence related to the peculiar environmental conditions of the underground site. PCR-ITS analysis and 16S rDNA sequences were used to clusterize and characterize the isolated strains. The presence of bacterial taxa associated to the photosynthetic microflora and fungi within the biofilm contributed to clarify the relationships inside the microbial community and to explain the alteration observed at the different sites. These results will contribute to the application of more successful strategies for the preventive conservation of subterranean archaeological sites. [ABSTRACT FROM AUTHOR]

Summary: We examined the presence of pesticides in the Llobregat river basin (Barcelona, Spain) and their effects on benthic biological communities (invertebrates and diatoms). The Llobregat river is one of Barcelona’s major drinking water resources. It has been highly polluted by industrial, agricultural, and urban wastewaters, and—as a typical Mediterranean river—is regularly subjected to periodic floods and droughts. Water scarcity periods result in reduced water flow and dilution capacity, increasing the potential environmental risk of pollutants. Seven sites were selected, where we analysed the occurrence of 22 pesticides (belonging to the classes of triazines, organophosphates, phenylureas, anilides, chloroacetanilides, acidic herbicides and thiocarbamates) in the water and sediment, and the benthic community structure. Biofilm samples were taken to measure several metrics related to both the algal and bacterial components of fluvial biofilms. Multivariate analyses revealed a potential relationship between triazine-type herbicides and the distribution of the diatom community, although no evidence of disruption in the invertebrate community distribution was found. Biofilm metrics were used as response variables rather than abundances of individual species to identify possible cause-effect relationships between pesticide pollution and biotic responses. Certain effects of organophosphates and phenylureas in both structural and functional aspects of the biofilm community were suggested, but the sensitivity of each metric to particular stressors must be assessed before we can confidently assign causality. Complemented with laboratory experiments, which are needed to confirm causality, this approach could be successfully incorporated into environmental risk assessments to better summarise biotic integrity and improve the ecological management. [Copyright &y& Elsevier]

Four algal photosynthetic biofilms were collected from the Rio Tinto (SW Spain) at four localities: AG, Euglena and Pinnularia biofilms; ANG, Chlorella and Pinnularia biofilms; RI, Cyanidium and Dunaliella biofilms; and CEM, Cyanidium, Euglena and Pinnularia biofilms. Community composition and structure were studied by a polyphasic approach consisting of 16S rRNA analysis, scanning electron microscopy by back-scattered electron detection mode (SEM-BSE), and fluorescence in-situ hybridization (FISH). Acidophilic prokaryotes associated with algal photosynthetic biofilms included sequences related to the Alpha-, Beta-, and Gammaproteobacteria (phylum Proteobacteria) and to the phyla Nitrospira, Actinobacteria, Acidobacteria and Firmicutes. Sequences from the Archaea domain were also identified. No more than seven distinct lineages were detected in any biofilm, except for those from RI, which contained fewer groups of Bacteria. Prokaryotic communities of the thinnest algal photosynthetic biofilms (<100 µm) were more related to those in the water column, including Leptospirillum populations. In general, thick biofilms (>200 µm) generate microniches that could facilitate the development of less-adapted microorganisms (coming from the surrounding environment) to extreme conditions, thus resulting in a more diverse prokaryotic biofilm [ABSTRACT FROM AUTHOR]

The structural organization of microbial mats from the Ebro Delta (Spain) and their accretion and partial lithification processes were explored using scanning electron microscopy in back-scattered electron mode and low-temperature scanning electron microscopy. Two differentiated zones were distinguished in a transverse section of a fragment taken from the mat at a depth of 2.5 mm. The first consisted of an upper layer in which the dominant microorganisms, Microcoleus spp., actively grew in an embedded slack matrix of exopolysaccharides. Microcoleus filaments were oriented parallel to the surface and to each other, with filaments below arranged perpendicularly to one another but without crossing. Most of the minerals present were allochthonous grains of calcium phosphate biocorroded by cyanobacteria. The second zone was below a depth of 1 mm and made up of accretion layers with large deposits of calcium carbonate and smaller amounts of calcium phosphate of biological origin. The predominance of a particular type of mineral precipitation with a characteristic external shape and/or texture within a zone, e.g., sponge-like deposits of calcium phosphate, appears to depend on the taxa of the prevailing microorganisms. [ABSTRACT FROM AUTHOR]

The aim of our study was to understand the role of the nematode community in a cyanobacterial-dominated biofilm located in the river Llobregat, NE Spain. This biofilm was mainly composed of oscillatorial species and diatoms. Fractions of these mats can become detached from the substrata and become free-floating, dispersing downstream and acquiring different structural and physiological properties. Both cyanobacterial biofilms, attached and free-floating, were compared with another benthic biofilm that occurred in the reach of the river that was studied. The nematode diversity was restricted, and was dominated by Chromadorita leuckarti, Diplogaster rivalis, Plectus parvus, Neotobrilus diversipapillatus, Monhystera spp., Dorylaimus sp. and Mononchus sp. Nematode density and biomass were significantly greater in the free-floating biofilm (maximum values of 752 ind/cm2 and 171.3 μgC/cm2). Different trophic and sexual strategies were observed. The free-floating biofilm showed higher abundances of juveniles and a high proportion of gravid females. A positive correlation was observed between cyanobacterial density and the abundance of juveniles or adults of the commonest nematode species, indicating their potential as food resources. [ABSTRACT FROM AUTHOR]

The community composition and ecophysiological features of microbial autotrophic biofilms were studied in Fuente Podrida, a cold sulfur spring located in East Spain. We demonstrated how different ecophysiological strategies, such as resistance and/or utilization of sulfide and oxygen, light adaptation, or resistance to high water flow, allow each of the microorganisms described to efficiently colonize several areas within the environmental gradient. In the zone of the spring constantly influenced by sulfide-rich waters, biofilms were formed by purple bacteria, cyanobacteria, and filamentous colorless sulfur bacteria. Purple bacteria showed higher photosynthetic efficiency per pigment unit than cyanobacteria, although they were dominant only in anoxic areas. Two filamentous cyanobacteria, strain UVFP1 and strain UVFP2, were also abundant in the sulfide-rich area. Whereas the cyanobacterial strain UVFP2 shows a strategy based on the resistance to sulfide of oxygenic photosynthesis, strain UVFP1, additionally, has the capacity for sulfide-driven anoxygenic photosynthesis. Molecular phylogenetic analyses cluster the benthic strain UVFP1 with genus Planktothrix, but with no particular species, whereas UVFP2 does not closely cluster with any known cyanobacterial species. The colorless sulfur bacterium Thiothrix sp. extended throughout the zone in which both sulfide and oxygen were present, exhibiting its capacity for chemolithoautotrophic dark carbon fixation. Downstream from the source, where springwater mixes with well-oxygenated stream water and sulfide disappears, autotrophic biofilms were dominated by diatoms showing higher photosynthetic rates than cyanobacteria and, by a lesser extent, by a sulfide-sensitive cyanobacterium (strain UVFP3) well adapted to low light availability, although in the areas of higher water velocity far from the river shore, the dominance shifted to crust-forming cyanobacteria. Both types of microorganisms were highly sensitive to sulfide impeding them from occupying sulfide-rich areas of the spring. Sulfide, oxygen, light availability, and water velocity appear as the main factors structuring the autotrophic community of Fuente Podrida spring. [ABSTRACT FROM AUTHOR]

Examines the structure and activity of rock and sand biofilms in a Mediterranean stream at the Riera Major in Spain. Role of microbial benthic community living in streams in organic matter processing; Impact of epilithic biofilms and epipsammic biofilms in the degradation of organic matter; Measurement of extracellular enzymatic activities.

Host-rock, speleothems, and rock art paintings from Altamira and Tito Bustillo Caves (northern Spain) are coated by dense biofilms of phototrophic microorganisms (cyanobacteria and algae) and networks of heterotrophic bacteria (mainly actinomycetes). These microorganisms induce constructive (calcification, crystalline precipitates) and destructive fabrics (irregular etching, spiky calcite). To assess the microbial impact on both caves - which contain valuable rock art paintings - mineralogical, petrographical, hydrochemical, microenvironmental, and microbiological studies were carried out. The identified damage includes: (1) covering (scattered colored spots, whitish powdery patinas)of paintings by the microbial communities themselves and/or by their metabolic activity (including biofilms and 'bioinduced' precipitates); (2) chemical alteration, such as microbially mediated dissolution; and (3) mechanical alteration, such as substratum breakdown and scaling. In addition, some types of speleothems, such as hydromagnesite coatings, traditionally attributed to inorganic precipitation, can be considered to be a product of microbial activity, as this activity could foster the precipitation of Ca–Mg-carbonates by creating conditions of high alkalinity with low PCO[sub 2] values. Hydrochemical, geochemical, and microenvironmental data exclude an inorganic process in the precipitation of hydromagnesite and huntite in Altamira Cave. [ABSTRACT FROM AUTHOR]

River biofilm communities are the first ones to be exposed to all toxic discharges received via run off from agricultural fields. Hence, changes in river biofilm community structure and growth pattern are considered as indicator of overall health of lotic ecosystem. Toxicants have effect on biofilm biomass, photosynthetic efficiency and chlorophyll a concentrations. Mathematical models may be applied to estimate the overall vigor of riverine ecosystems considering biofilms as indicators. Herein, previous empirical data of Ricart et al. (2009) on long term effects of environmentally relevant concentrations of diuron on biofilm communities of the River Llobregat, Spain was considered as our model inputs. Our objective is to understand the influence of diuron, chlorophyll a concentrations and photosynthetic efficiency on biovolume using a statistical model. The non-linear relationships between biovolume (dependent variable) and diuron, chlorophyll a concentrations and photosynthetic efficiency (independent variables) were represented by constructing three separate basis functions based on day 8 empirical data. Biovolume, due to nonlinear influence as yielded by the basis functions were used in a multiple linear regression model to estimate the net biovolume. Model validation was done based on day 29 empirical data. The experimentally determined biovolume and our model estimated biovolume showed similar trends. Also, diuron and photosynthetic efficiency had significant (p < 0.05) influence on biovolume. Since, the predominance of diatoms as biofilms within periphytic layers is very common in lotic systems, estimation of changes in diatom biovolume will be significant to assess the effect of herbicides. Diatom biovolume of any day (for example day 22) mentioned in the experimental study may be determined by this model, without the requirement of tedious manual biovolume calculation. Our model will be useful in numerous other studies undertaken on the toxic effect of pollutants on biofilms to quickly and accurately estimate the biofilm biovolume. • Statistical model estimates river ecosystem health considering biofilm as indicator. • Multiple linear regression following basis function applied for biovolume estimation. • Future studies can estimate biovolume using our proposed two-step statistical model. [ABSTRACT FROM AUTHOR]

The combined effects of UV-A or UV-B radiation and red LED light on subaerial biofilm formation were studied. Biofilms were generated using cultures isolated from natural phototrophic biofilms growing on the granite facades of the Palace of Xelmírez and the Monastery of San Martiño Pinario, both historic buildings in Santiago de Compostela (NW Spain). Red LED and UV-A or UV-B radiation were tested separately and together in the same experiment, along with white LED (positive control) and no LED or UV lights (i.e. darkness, negative control). The initial target biofilms had different ratios of green algae: cyanobacteria [cells mL−1] of 100:1 (Xelmírez) and 5:1 (Pinario). Relative to the other treatments, the combination of UV-A and red LED significantly enhanced growth of the biofilm mainly comprising algae. Relative to the negative control, proliferation of Isocystis sp. and Stichococcus bacillaris also increased (by respectively 10% and 36% in Xelmírez and by 2% and 44% in Pinario), while the occurrence of Bracteacoccus minor decreased (by 47% in Xelmírez and 46% in Pinario). UV-B plus red LED also impeded the proliferation of Bracteacoccus minor (by 7% in Xelmírez and 14% in Pinario), but conversely resulted in poor biofilm growth. • The impact of UV + red LED on biofilm development was studied for the first time. • Effects of UV + red LED depend on the type and ratio of phototrophs in the biofilm. • UV-A + red LED light stimulates growth of subaerial biofilms mainly comprising algae. • UV-A + red LED light enhances S. bacillaris and impedes B. minor proliferation. • UV-B + red LED decreases biofilm growth and chlorophyll fluorescence (activity). [ABSTRACT FROM AUTHOR]

Submersion time of collector ropes influences settlement and larval metamorphosis of Mytilus galloprovincialis, which might be related to the biofilm development. In the present study, the effect of submersion time of collector ropes on the settlement of mussel seed was studied. The results of two experiments performed in an experimental long-line in the Ría de Ares-Betanzos have established a minimum submersion time of 41–46 days. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA) is a prevalent nosocomial pathogen, causing a wide range of diseases. The increased frequency of MRSA isolates in hospitals and the emergence of vancomycin resistance have sparked the search for new control strategies. This study aimed to characterize sixty-seven MRSA isolates collected from both infected patients and asymptomatic carriers in a Spanish hospital. RAPD-PCR allowed the identification of six genetic patterns. We also investigated the presence of genes involved in producing adhesins, toxins and the capsule; the biofilm; and antimicrobial resistance. A notable percentage of the isolates carried virulence genes and showed medium-high ability to form biofilms. Next, we assessed the strains' susceptibility to two phages (phiIPLA-C1C and phiIPLA-RODI) and one endolysin (LysRODI). All strains were resistant to phiIPLA-C1C, and most (70.2%) were susceptible to phiIPLA-RODI. Regarding LysRODI, all strains displayed susceptibility, although to varying degrees. There was a correlation between endolysin susceptibility and the random amplification of polymorphic DNA (RAPD) profile or the presence of some virulence genes (fnbA, eta, etb, PVL and czr), but that was not observed with biofilm-forming ability, strain origin or phage sensitivity. Taken together, these findings can help to explain the factors influencing endolysin effectiveness, which will contribute to the development of efficient therapies targeting MRSA infections. [ABSTRACT FROM AUTHOR]

Pollution from human activities is a major threat to the ecological integrity of fluvial ecosystems. Microbial communities are the most abundant organisms in biofilms, and are key indicators of various pollutants. We investigated the effects some human stressors (nutrients and heavy metals) have on the structure and activity of microbial communities in seven sampling sites located in the Ter River basin (NE Spain). Water and biofilm samples were collected in order to characterize physicochemical and biofilm parameters. The 16S rRNA gene was analysed out from DNA and RNA extracts to obtain α and β diversity. Principal coordinates analyses (PCoA) of the operational taxonomic units (OTUs) in the resident microbial community revealed that nutrients and conductivity were the main driving forces behind the diversity and composition. The effects of mining have had mainly seen on the taxonomic composition of the active microbial community, but also at the OTUs level. Remarkably, metal-impacted communities were very active, which would indicate a close link with the stress faced, that is probably related to the stimulation of detoxification. Image 1 • Effects of nutrients and heavy metals on microbial communities from fluvial biofilms were studied. • Extraction of nucleic acids (DNA and RNA) provides complementary information of dynamics of microbial communities. • Nutrients and conductivity change the diversity and composition of resident microbial community. • Effects of mining metals are shown in the active microbial community at OTUs level. • Five genus of bacteria are proposed as potential bioindicators of low and chronic metal pollution. [ABSTRACT FROM AUTHOR]

The global increase of cyanobacterial blooms occurrence has been associated with the presence of compounds that generate earthy and musty odor in freshwater systems, among which geosmin stands out. The lack of information on the factors associated to geosmin production by benthic organisms has driven the development of this study, whose main goal is to determine the effects of nutrient concentration and DIN:SRP ratio on geosmin formation and release. The experiment was performed in 18 microcosms under controlled conditions for 21 days, using a natural biofilm suspension from Ter river (NE, Spain) to promote biofilm settlement. Six treatments were set crossing three DIN:SRP ratios (A = 4:1, B = 16:1 and C = 64:1) with two nutrient concentrations (Low and High). After 7 days of experiment, geosmin was detected in biofilm, being higher under high nutrient concentration and low DIN:SRP ratio conditions. In this treatment, geosmin in biofilm reached its maximum concentration at day 16 (3.8 ± 0.9 ng/mg), decreasing at the end of the experiment (21d) due to cyanobacteria detachment and geosmin release into the water (136 ± 6 ng/L). Overall, this experimental study showed that high nutrient concentration and low DIN:SRP ratio favored the Oscillatoria genus development within biofilm communities, generating the optimal conditions for geosmin production. The interaction between these two factors was demonstrated to be a potential driver of benthic geosmin production and release, and should be monitored and controlled in rivers exploited for drinking water purposes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A variety of natural biofilms were collected from an extremely acidic environment at Río Tinto (Spain). In order to provide insights into the structure-function relationship, the microstructure of the biofilms was explored using low temperature scanning electron microscopy (LTSEM) in combination with rheological analysis. The creep-recovery experiment results have demonstrated the typical behaviour of viscoelastic materials that combine both elastic and viscous characters. The LTSEM visualization and rheological characterization of biofilms revealed that the network density increased in bacterial biofilms and was the lowest in protist Euglena biofilms. This means that, in the latter biofilms, a lower density of interactions exist, suggesting that the whole system experiences enhanced mobility under external mechanical stress. The samples with the highest dynamic moduli (Leptospirillum-Acidiphilium, Zygnemopsis, Chlorella and Cyanidium) have shown the typical strain thinning behaviour, whereas the Pinnularia and Euglena biofilms exhibited a viscous thickening reaction. The Zygnemopsis filamentous floating structure has the highest cohesive energy and has shown distinctive enhanced resilience and connectivity. This suggests that biofilms should be viewed as soft viscoelastic systems the properties of which are determined by the main organisms and their extracellular polymeric substances. The fractional Maxwell model has been found to explain the rheological behaviour of the observed complex quite well, particularly the power-law behaviour and the characteristic broad relaxation response of these systems.

Electrical lighting favours the development of photosynthetic biofilms in caves which can induce biodeterioration in the colonized substrates. The use of specific lights as a limiting factor for biofilm growth could be effective in their control and represents an alternative to chemical methods since they can damage the substrate. However, studies about lighting and the photosynthetic activity of organisms in caves are scarce. In order to select the most effective LED light source in reducing photosynthesis and therefore, in reducing the growth rates of microalgae and cyanobacteria, four biofilms in the Nerja Cave were illuminated by several light emitted diodes (LEDs) with different spectral compositions and the photobiological responses were measured both by empirical and theoretical methodologies. The empirical approach was based on the photosynthetic efficiency, by measuring the in vivo chlorophyll a (Chl a) fluorescence and the theoretical approach was based on the photonic assimilation performance related to the proportion of the light quality used for photosynthesis, according to the action spectra for photosynthesis available in the literature. The photobiological responses showed differences between the empirical and theoretical approach mainly in biofilms dominated by cyanobacteria and red algae, probably because the available action spectra were not useful for monitoring these Nerja Cave biofilms. However, the expected spectral responses of photosynthesis were observed in green microalgal biofilms with maximum photosynthetic efficiency in red and blue light although the green light was also unexpectedly high. The high photosynthetic efficiency in green light could be explained by the predictable high chlorophyll content due to a very dark environment. The results were not conclusive enough for all the biofilm types to be able to recommend a specific lighting system for the photocontrol of biofilm expansion. Therefore, new action spectra for photosynthesis of the extremophile organisms of the Nerja Cave are required. This approach, based on theoretical and empirical methodologies, is a useful tool to obtain information to allow the design of the most adequate lighting systems to reduce photosynthetic activity and favour the conservation of the caves., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Drinking water distribution systems host extensive microbiomes with diverse biofilm communities regardless of treatment, disinfection, or operational practices. In Mediterranean countries higher temperatures can accelerate reactions and microbial growth that may increase aesthetic water quality issues, particularly where material deposits can develop as a result of net zero flows within looped urban networks. This study investigated the use of flow and turbidity monitoring to hydraulically manage mobilisation of pipe wall biofilms and associated material from the Mediterranean city of Valencia (Spain). Pipe sections of different properties were subjected to controlled incremental flushing with monitoring and sample collection for physico-chemical and DNA analysis with Illumina sequencing of bacterial and fungal communities. A core microbial community was detected throughout the network with microorganisms like Pseudomonas, Aspergillus or Alternaria increasing during flushing, indicating greater abundance in underlying and more consolidated material layers. Bacterial and fungal communities were found to be highly correlated, with bacteria more diverse and dynamic during flushing whilst fungi were more dominant and less variable between sampling sites. Results highlight that water quality management can be achieved through hydraulic strategies yet understanding community dynamics, including the fungal component, will be key to maintaining safe and ultimately beneficial microbiomes in drinking water distribution systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

We aim to assess intra- and interspecies differences in the virulence of Candida spp. strains causing candidemia using the invertebrate Galleria mellonella model. We studied 739 Candida spp. isolates (C. albicans [n = 373], C. parapsilosis [n = 203], C. glabrata [n = 92], C. tropicalis [n = 53], and C. krusei [n = 18]) collected from patients with candidemia admitted to Gregorio Marañon Hospital (Madrid, Spain). Species-specific infecting inocula (yeast cells/larva) were adjusted (5 × 105 [C. albicans, and C. tropicalis], 2 × 106-5 × 106 [C. parapsilosis, C. glabrata, and C. krusei]) and used to infect 10 larvae per isolate; percentage of survival and median survival per isolate were calculated. According to the interquartile range of the median survival, isolates with a median survival under P25 were classified as of high-virulence and isolates with a median survival over P75 as of low virulence. The median survival of larvae infected with different species was variable: C. albicans (n = 2 days, IQR <1-3 days), C. tropicalis (n = 2 days, IQR 1.5-4 days), C. parapsilosis (n = 2 days, IQR 2-3.5 days), C. glabrata (n = 3 days, IQR 2-3 days), and C. krusei (n = 7 days, 6.5->8 days) (P < .001). Differences in virulence among species were validated by histological examination (day +1 post-infection) in the larvae infected by the isolates of each virulence category and species. Virulence-related gene expression in C. albicans isolates did not reach statistical significance. We report species-specific virulence patterns of Candida spp. and show that isolates within a given species have different degrees of virulence in the animal model., (© The Author(s) 2019. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology.)

A study was undertaken of the presence of Listeria monocytogenes in 260 samples of poultry meat obtained from retail outlets in northwestern Spain. L. monocytogenes was detected in 20 samples (7.7%). Twenty strains (one strain per positive sample) were characterized. The strains belonged to 10 serotypes: 1/2a (2 strains), 1/2b (2), 1/2c (2), 3a (1), 3b (2), 3c (2), 4a (2), 4b (4), 4c (1), and 4d (2). Cluster analysis (ribotyping; EcoRI) showed a strong genetic relationship between strains isolated from samples coming from different outlets. Ribotyping permitted some isolates of the same serotype to be differentiated, which points to the possible usefulness of this technique in the epidemiological surveillance of L. monocytogenes. All strains formed biofilm on polystyrene, as shown by confocal laser scanning microscopy. The biovolume (between 621.7 ± 36.0 µm3 and 62,984.0 ± 14,888.2 µm3 in the observational field of 14,161 μm2), percentage of surface coverage (from 2.17 ± 0.84% to 94.43 ± 3.97%), roughness (between 0.399 ± 0.052 and 0.830 ± 0.022), and maximum thickness (between 9.00 ± 0.00 µm and 24.00 ± 14.93 µm) of biofilms varied between strains (p < 0.05). These results expand knowledge of the characteristics of L. monocytogenes isolates from poultry. [ABSTRACT FROM AUTHOR]

The ability to establish biofilms is a key trait for microorganisms growing in extreme environments. The extracellular polymeric substances (EPS) present in biofilms provide not only surface attachment, but also protection against all kinds of environmental stressors, including desiccation, salinity, temperature or heavy metal pollution. The acquisition of suitable biofilm characteristics might thus be an important process mediating the adaptation of microorganisms to novel environmental conditions. In this work we have characterized the EPS of 20 phylogenetically diverse biofilms collected in situ from five contrasting extreme environments, including two geothermal areas (Copahue, Argentina; Seltun, Iceland), two cold areas (Pastoruri glacier, Peru; Byers Peninsula, Antarctica) and one extremely acidic river (Río Tinto, Spain). Biofilms were subjected to biochemical characterization, glycan profiling and immunoprofiling with an antibody microarray. Our results showed that environmental conditions strongly influence biofilm characteristics, with microorganisms from the same environment achieving similar EPS compositions regardless of the phylogeny of their main species. The concentration of some monosaccharides in the EPS could be related to environmental conditions such as temperature or heavy metal toxicity, suggesting that in some cases stress resistance can be mediated by specific sugars. Overall, our results highlight the existence of conserved EPS compositional patterns for each extreme environment, which could in turn be exploited to engineer ecological adaptations in genetically modified microorganisms., (Copyright © 2018 Elsevier B.V. All rights reserved.)