Search

In this preliminary screening, we assessed the antibacterial activity of in vitro obtained plant material, namely shoots of Artemisia eriantha (Asteraceae) and callus of Ocimum basilicum L. var. ʻSpicy globeʼ, against two bacteria strains, the Gram-positive ones including Staphylococcus aureus ATCC 25923, and Gram-negative, Escherichia coli ATCC 25922 by the plate-counting method. Artemisia sprouted on the Murashige-Skoog medium added with 1.5 mg/L benzylaminopurine and ʻSpicy globeʼ basil developed callus on Murashige - Skook basal medium supplemented with 2.5 mg/L naphtylacetic acid (NAA). The method of using small pieces of vegetal material inoculated in Erlenmeyer flasks on liquid Luria-Bertani medium added with standardized microbial cell suspension was not effective against the pathogenic bacteria in the case of the Artemisia species, but the same method was efficient for basil cultivar ʻSpicy globeʼ.

Based on the balneotherapeutic applications of mineral spring water and particularly sulphurous water, the aim of our research was to study the physicochemical and microbiological parameters of some drainage waters of Siriu dam that showed a strong hydrogen sulphide odour. In addition, due to the corrosive effect of some groups of microorganisms, such as iron-oxidizing bacteria and sulphatereducing bacteria, the present paper also aimed to detect their presence in order to signal the need for some disinfection measures. According to physicochemical analysis, there has been found an external drain that is suitable for use in balneotherapy, presenting a balanced content of mineral elements such as sulphur, calcium, silicon, chlorine and potassium. However, due to the presence of potentially toxic phytoplankton microorganisms such as Microcystis sp. and Phormidium sp. it is necessary to disinfect this water source before using it for any purpose. On the other hand, the identification of both sulphate-reducing bacteria and iron-oxidizing bacteria in the drainage waters of Siriu dam should be considered as an alarm signal as they may lead to bio-corrosion and deterioration of metallic or concrete structures, affecting the integrity of the dam and hydropower constructions.

Traditionally fermented foods and beverages are still produced and consumed at a large scale in Romania. They are rich sources for novel lactic acid bacteria with functional properties and with potential application in food industry or health. Lactobacillus helveticus 34.9, isolated from a home-made fermented milk is able to inhibit the growth of other bacteria, such as other lactic acid bacteria, but also strains of Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Halobacillus hunanensis, a halobacterium isolated from the degraded wall of a Romanian monastery. L. helveticus 34.9 produces a large bacteriocin (35 KDa), active in a wide pH range, but inactivated by heat and proteinase K treatment. It shares about 20% sequence coverage with helveticin J, as determined by LC-MS analysis. Bacteriocin production was enhanced under stress conditions, especially when combined stresses were applied. Its mode of action and degree of inhibition depended on the concentration and on the indicator strain that was used; L. delbrueckii subsp. bulgaricus LMG 6901

The purpose of this paper was to isolate halophiles from Letea saline lake and to performed a screening for industrially relevant extracellular enzymes. The investigations were conducted from October 2016 until May 2018. After a random selection of colonies that grew on the medium culture, 82 isolates were investigated. Based on their salt requirements and tolerance, it was remarked the presence of isolates belonging to halotolerant and moderate halophilic bacteria. Morphological and biochemical tests were used to characterize them. The ability of the tested isolates to produce extracellular enzymes was evaluated on the culture medium with salinity varying between 0-4M and supplemented with a specific substrate. The highest hydrolytic activities were recorded for casein at 0M NaCl, 1M NaCl, 2M NaCl, and Tween 80 and inulin at 0M NaCl, 1M NaCl, 2M NaCl, and 3M NaCl.

Urban areas face numerous provocations, such as air, water, and soil contamination. Additionally, urban lakes have numerous beneficial services that contribute to urban sustainability. In urban aquatic ecosystems, X-ray fluorescence can provide complex answers regarding the presence of elements associated with environmental risk. The study aimed to screen the elements with different potentials (critical raw materials—CRMs; toxic; potentially toxic) from Phragmites australis leaves along the Colentina urban river. The samples from the peri-urban and urban river courses highlighted the presence of elements with different potentials for ecosystems and human health. The investigated stations were influenced by regional anthropogenic pressures, where P. australis highlighted the absorption of the dominant elements found in the environment. From the total of 56 elements present in the samples, some have structural roles (K, Si, Ca, and Cl), some are from the CRM category, and some are airborne heavy metals and rare metals. Furthermore, among CRMs, cesium, lanthanum, magnesium, phosphorus, vanadium, sulfur, holmium, and titanium were recorded with higher values. Although the values of the elements in the anthropogenic source were in low concentrations, spatial differences were highlighted. The stations in agricultural areas were different from the peri-urban and urban ones.

Traditionally fermented foods and beverages are still produced and consumed at a large scale in Romania. They are rich sources for novel lactic acid bacteria with functional properties and with potential application in food industry or health. Lactobacillus helveticus 34.9, isolated from a home-made fermented milk is able to inhibit the growth of other bacteria, such as other lactic acid bacteria, but also strains of Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Halobacillus hunanensis, a halobacterium isolated from the degraded wall of a Romanian monastery. L. helveticus 34.9 produces a large bacteriocin (35 KDa), active in a wide pH range, but inactivated by heat and proteinase K treatment. Bacteriocin production was enhanced under stress conditions, especially when combined stresses were applied. Its mode of action and degree of inhibition depended on the indicator strain and on the concentration of bacteriocin that was used. L. delbrueckii subsp. bulgaricus LMG 6901T cells from a suspension were killed within 8 h, but the viability of H. hunanensis 5Hum cells was only reduced to 60%. However, the bacteriocin was able to prevent the bacterial growth of both indicator strains when added to the medium prior inoculation. Scanning electron microscopy images revealed morphological changes induced by the bacteriocin treatment in both sensitive strains, but more severe in the case of L. delbrueckii subsp. bulgaricus. This class III bacteriocin, with inhibitory activity against various bacterial species, may find application in food and non-food related fields, including in the restoration of historical buildings.

Cellulases are a group of enzymes that are used in many biotechnological processes. Since most of the enzymes synthesised by mesophilic microorganisms are unstable in industrial environments, it is necessary to direct research towards extremophile cellulolytic microorganisms because the enzymes synthesised by them are stable and active even in harsh physicochemical conditions. In the present investigation, our aim was to isolate and identify some microbial cellulolytic strains from a hypersaline lake located in Romania and to determine their optimal growth conditions. Of a total of 25 microbial strains isolated, only one extreme halotolerant bacterial strain was able to produce an endoglucanase. Based on molecular identification, we identified this cellulolytic strain as a species of Bacillus genus, most closely related to Bacillus zhangzhouensis. Optimal growth conditions were found to be at 15°C, pH 7.5 and 2 M NaCl. Endoglucanase activity of this bacterial strain is influenced by both salinity and temperature. The most significant endoglucanase activity was detected in the presence of 3 M NaCl, after 72 h of incubation at 15°C. In this situation, the amount of glucose released from a volume of 0.5 mL of 2% (w/v) carboxymethyl cellulose substrate is equivalent to 2.05 mg. In conclusion, this study represents the first preliminary characterization of a B. zhangzhouensis strain that has the ability to degrade cellulose and that demonstrates tolerance to high salt concentrations.

This study analyzed the metabolic potential of some functional groups of bacteria in aquatic urban systems and evaluated the abundance of communities of total heterotrophic bacteria in the water in relation to the monitored physico-chemical factors. The results obtained showed seasonal differences, especially in spring. The high values of the abundance of heterotrophs in winter are related to human activity at the sampling stations. Screening for four types of extracellular hydrolytic enzyme with potential for degradation of organic matter (amylases, lipases, proteases and cellulases) led to the conclusion that lipolytic bacteria were dominant in the studied ecosystems, while proteolytic bacteria were observed in low numbers, but were present in urbanized areas. The presence of cellulolytic bacteria is correlated with the development of macrophytic vegetation. The aim of the present study was oriented towards the evaluation of the anthropogenic input in several lakes surrounding Bucharest in the Nord-Eastern region. These urban ecosystems are generated as a requirement of city development. The microbiological and general enzymatic approaches generated some novel results concerning the pollution degree of aquatic urban ecosystems and could be considered as a platform for further investigation.

One of the main by-products resulted from the biodiesel industry is represented by waste glycerol which is known as a mixture between glycerol and various salts, soaps, fatty acids and other chemical compounds. This composition makes it very difficult to be used in other domains and the large amounts in which it is obtained raise storage and environmental problems. Within this framework, its bioconversion to other products by several microorganisms could be regarded as a most valuable and convenient alternative. In this work, the transformation of waste glycerol to carotenoid compounds, namely phytoene and β-carotene by several wild strains of halophilic microorganisms isolated from a saline lake is presented. The structures of the investigated carotenes were analysed by FT-IR and UV–Vis spectrometry while differential scanning microcalorimetry (μDSC) evaluated the thermal behaviour of the methanol solution of the pigments obtained from microbial cultures. The growth of microorganisms was estimated by measuring optical density at 660 nm using a BMG LABTECH FLUOstar Omega microplate reader and carotenes were extracted with methanol. The data recorded until now revealed that the presence of waste glycerol from several sources in the composition of culture medium resulted in growing of phytoene content. These compounds are known as precursors for obtaining other carotenoid compounds either in natural synthesis or in chemical industry. In case of β-carotene, the preliminary results revealed a slow decrease of its content in the presence of waste glycerol as a major growth substrate. The presence of waste glycerol in culture medium leads to thermograms for pigments’ methanol solutions with larger thermal effects than those obtained in the absence of waste glycerol. The absorption spectra of the pigments isolated form strains LD2 and LN1-10 display a typical shape for carotenoids in the 400–500 nm wavelength range and for phytoene in the 250–300 nm wavelength range. The absorption spectra of the strains LN4-1, LC37 and LN2-5 indicate the presence of phytoene and the absence of carotenoids.

Considering that most industrial processes are carried out under harsh physicochemical conditions, which would inactivate enzymes from commonly isolated mesophilic organisms, current studies are geared toward the identification of extremophilic microorganisms producing enzymes resistant to extreme salt concentrations, temperature and pH. Among the extremophiles, halophilic microorganisms are an important source of salt-tolerant enzymes that can be used in varying biotechnological applications. In this context, the aim of the present work was to isolate and identify halophiles producing hydrolases from the Atacama Desert, one of the harshest environments on Earth. Isolates were recovered from halite samples and screened for the presence of seven different hydrolase activities (amylase, caseinase, gelatinase, lipase, pectinase, cellulase and inulinase) using agar plate-based assays. From a total of 23 halophilic bacterial isolates, most showed lipolytic (19 strains) and pectinolytic (11 strains) activities. The molecular identification of eight selected isolates showed a strong similarity to members of the Halomonas and Idiomarina genera. Therefore, the present study represents a preliminary, but essential, step to identify novel biological sources of extremozymes in an environment once thought to be devoid of life.

The waste glycerol representing the main secondary product in biodiesel industry is obtained in large amounts whose storage raise environmental problems. The bioconversion of this product to other product by various microorganisms represents a convenient alternative. Several enzymes are involved in waste glycerol conversion and among these the lipase has a great biotechnological importance. This work deals with the isolation, purification and kinetic characterization of lipase from moderately halophilic and halotolerant strains, namely Marinococcus halophilus JCM 2472 and strain S3-6. The purified enzyme showed catalytic activity at pH 8–10 and in a wide range of temperatures between 15 and 70 °C with optimum at values over 60 °C. The data recorded for the effect of sodium chloride content revealed the halotolerant character of the investigated enzymes with optimum activity at 1 M NaCl and being active between 0 and 3 M. The concentration of the substrate i.e. olive oil, sun-flower oil, has no effect on the lipase activity. The cultivation conditions of the microbial strains and the effect of culture media composition for obtaining the enzyme are also presented in this study.

The Horezu Monastery is dating from the seventeenth century, but the refectory was built in the western side of its axis and painted in the early eighteenth centuries. The main objective of the work is to perform a deep analysis of pink and black pigmentation from the refectory and the cellar. It started from the pink coloration observed by the naked eye followed by photographic registration and analysis by mobile optical microscope. Then micro samples have been taken for analysis at optical and electronic microscope and resin embedding to obtain cross-sections. Photographic registration is a useful method to map pink pigmentation but microscopy and microbiological analysis are essential for finding its biological origin. Spherical cells like Rubrobacter grouped in chains or tetrads developing a pink biofilm and filamentous branching bacteria like actinomyces were identified on the surface of mortar, mural painting and bricks. Many groups of bacteria have been found in cracks and pores. This observation explains the ability of pink bacteria to travel through pores and clog them impairing water evaporation. Black pigmentation is the result of mortar colonization by fungi which developed both mycelium and conidiophores with conidia. Examination of the samples by lens and electrons allows scientists and restorers to identify the microbiological origin of the pink and black discoloration and to avoid their misinterpretation as colors which are coming from chemical reactions or deposits from the atmosphere. Based on these results, a strategy for decontamination is elaborated to be applied before restoration work.

In this study we investigated the security of a spaceflight experiment from two points of view: spreading of dried fungal spores placed on the different wafers and their viability during short and long term missions on the International Space Station (ISS). Microscopic characteristics of spores from dried spores samples were investigated, as well as the morphology of the colonies obtained from spores that survived during mission. The selected fungal species were: Aspergillus niger, Cladosporium herbarum, Ulocladium chartarum, and Basipetospora halophila. They have been chosen mainly based on their involvement in the biodeterioration of different substrate in the ISS as well as their presence as possible contaminants of the ISS. From biological point of view, three of the selected species are black fungi, with high melanin content and therefore highly resistant to space radiation. The visual inspection and analysis of the images taken before and after the short and the long term experiments have shown that all biocontainers were returned to Earth without damages. Microscope images of the lids of the culture plates revealed that the spores of all species were actually not detached from the surface of the wafers and did not contaminate the lids. From the adhesion point of view all types of wafers can be used in space experiments, with a special comment on the viability in the particular case of iron wafers when used for spores that belong to B. halophila (halophilic strain). This is encouraging in performing experiments with fungi without risking contamination. The spore viability was lower in the experiment for long time to ISS conditions than that of the short experiment. From the observations, it is suggested that the environment of the enclosed biocontainer, as well as the species'specific behaviour have an important effect, reducing the viability in time. Even the spores were not detached from the surface of the wafers, it was observed that spores used in the long term experiment lost the outer layer of their coat without affecting the viability since they were still protected by the middle and the inner layer of the coating. This research highlights a new protocol to perform spaceflight experiments inside the ISS with fungal spores in microgravity conditions, under the additional effect of possible cosmic radiation. According to this protocol the results are expressed in terms of viability, microscopic and morphological changes.

Halophilic bacterial strains isolated from a man-made salt lake in Romania produce a specific exopolysaccharide. This product is synthesized under both static and stirring conditions, and the yield of this exoploysaccharide depends on the composition of the culture medium. The highest amount of polymer was obtained in the presence of casamino acids and yeast extract, under stirring conditions. This polymer has high thermostability, with a melting point at 207 degrees C. The melting process is associated with the thermal degradation of the compound. This polymer is characterized by maximum absorbtion at 260 nm and fluorescence emission at 530 nm. The FT-IR analysis of the polymer revealed the presence of a saccharide structure and of amine and sulfate groups throughout the sugar backbone.