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Oxidative bursts are a common mechanism used by higher organisms to defend themselves against bacterial attacks, but some pathogenic bacteria have evolved resistance mechanisms to counteract this. The role of oxidative stress resistance as a virulence trait in macroalgal disease is however unknown. Here, we demonstrate that the gene gpoA, encoding for a glutathione peroxidase, is important for the oxidative stress response of the macroalgal pathogen Nautella italica R11. We also show that a lack of gpoA prevents N. italica R11 from inducing a bleaching disease in the red alga Delisea pulchra. These results show that a defense against oxidative stress is likely to be an important feature enabling pathogenic bacteria to infect macroalgae., (© FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Awareness on antioxidants and its significance in human healthcare has increased many folds in recent time. Increased demand requisite on welcoming newer and alternative resources for natural antioxidants. Seaweed associated pigmented bacteria screened for its antioxidant potentials reveals 55.5% of the organisms were able to synthesize antioxidant compounds. DPPH assay showed 20% of the organisms to reach a antioxidant zone of 1 cm and 8.3% of the strains more than 3 cm. Pseudomonas koreensis (JX915782) a Sargassum associated yellowish brown pigmented bacteria have better activity than known commercial antioxidant butylated hydroxytoluene (BHT) against DPPH scavenging. Serratia rubidaea (JX915783), an associate of Ulva sp. and Pseudomonas argentinensis (JX915781) an epiphyte of Chaetomorpha media , were also contributed significantly towards ABTS (7.2% ± 0.03 to 15.2 ± 0.09%; 1.8% ± 0.01 to 15.7 ± 0.22%) and FRAP (1.81 ± 0.01 to 9.35 ± 0.98; 7.97 ± 0.12 to 18.70 ± 1.84 μg/mL of AsA Eq.) respectively. 16S rRNA gene sequence analysis revealed bacteria that have higher antioxidant activity belongs to a bacterial class Gammaproteobacteria. Statistical analysis of phenolic contents in relation with other parameters like DPPH, ABTS, reducing power and FRAP are well correlated (p < 0.05). Results obtained from the current study inferred that the seaweed associated pigmented bacteria have enormous potential on antioxidant compounds and need to be extracted in a larger way for clinical applications.

In recent decade, seaweeds-associated microbial communities have been significantly evaluated for functional and chemical analyses. Such analyses let to conclude that seaweeds-associated microbial communities are highly diverse and rich sources of bioactive compounds of exceptional molecular structure. Extracting bioactive compounds from seaweed-associated microbial communities have been recently increased due to their broad-spectrum antimicrobial activities including antibacterial, antifungal, antiviral, anti-settlement, antiprotozoan, antiparasitic, and antitumor. These allelochemicals not only provide protection to host from other surrounding pelagic microorganisms, but also ensure their association with the host. Antimicrobial compounds from marine sources are promising and priority targets of biotechnological and pharmaceutical applications. This review describes the bioactive metabolites reported from seaweed-associated bacterial and fungal communities and illustrates their bioactivities. Biotechnological application of metagenomic approach for identifying novel bioactive metabolites is also dealt, in view of their future development as a strong tool to discover novel drug targets from seaweed-associated microbial communities.

Two reporter strains were established to identify novel biomolecules interfering with bacterial communication (quorum sensing [QS]). The basic design of these Escherichia coli-based systems comprises a gene encoding a lethal protein fused to promoters induced in the presence of QS signal molecules. Consequently, these E. coli strains are unable to grow in the presence of the respective QS signal molecules unless a nontoxic QS-interfering compound is present. The first reporter strain designed to detect autoinducer-2 (AI-2)-interfering activities (AI2-QQ.1) contained the E. coli ccdB lethal gene under the control of the E. coli lsrA promoter. The second reporter strain (AI1-QQ.1) contained the Vibrio fischeri luxI promoter fused to the ccdB gene to detect interference with acyl-homoserine lactones. Bacteria isolated from the surfaces of several marine eukarya were screened for quorum- quenching (QQ) activities using the established reporter systems AI1-QQ.1 and AI2-QQ.1. Out of 34 isolates, two interfered with acylated homoserine lactone (AHL) signaling, five interfered with AI-2 QS signaling, and 10 were demonstrated to interfere with both signal molecules. Open reading frames (ORFs) conferring QQ activity were identified for three selected isolates (Photobacterium sp., Pseudoalteromonas sp., and Vibrio parahaemolyticus). Evaluation of the respective heterologously expressed and purified QQ proteins confirmed their ability to interfere with the AHL and AI-2 signaling processes.

A taxonomic study was carried out on strain YN3(T), which was isolated from a seaweed sample taken from the coast of Weihai, China. The bacterium was Gram-stain-negative, rod-shaped, and could grow at pH 5.0-10.0 and 4-32 °C in the presence of 0-9.0 % (w/v) NaCl. Strain YN3(T) was positive for the hydrolysis of polysaccharides, such as agar, starch and xylan. The predominant respiratory quinone was ubiquinone-8. The major fatty acids were C16 : 1ω7c and/or iso-C15 : 0 2-OH, C16 : 0 and C18 : 1ω7c. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine, and two unidentified glycolipids. The genomic DNA G+C content was 49.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YN3(T) should be assigned to the genus Gilvimarinus. 'Gilvimarinus agarilyticus' KCTC 23325 and Gilvimarinus chinensis QM42(T) had the closest phylogenetic relationship to strain YN3(T), and showed 97.9 % and 95.8 % sequence similarities, respectively. On the basis of phenotypic, chemotaxonomic and genotypic data and DNA-DNA hybridization studies, we propose that strain YN3(T) represents a novel species of the genus Gilvimarinus, for which the name Gilvimarinus polysaccharolyticus sp. nov. is proposed. The type strain is YN3(T) ( = KCTC 32438(T) = JCM 19198(T)). An emended description of the genus Gilvimarinus is also presented., (© 2015 IUMS.)

The fatty acid (FA) profiles of 15 strains representing four genera (Vibrio, Pseudomonas, Aeromonas, and Shewanella) and seven species were compared by capillary gas chromatography with flame ionization detection. FA fingerprints of Vibrio parahaemolyticus were established by similarity calculation and principle component analysis. This provided a simple measure for distinguishing V. parahaemolyticus from other bacteria. The similarity scores indicated by correlation coefficient and vector cosine were divided into three regions and suggested that the strains with scores higher than 0.980 probably belonged to V. parahaemolyticus. However, samples with low scores (<0.850) were classified under other genera. Furthermore, the alterations in FA profiles of V. parahaemolyticus in the presence of various environmental pressures were investigated. The production of saturated FA (SFA) increased gradually concomitant with a decreased proportion of unsaturated FA (UFA) with rising temperature. Similarly, the SFA tended to increase at the expense of UFA with prolonged culture time. In addition, V. parahaemolyticus changed its FA profiles to contain increased short-chained FA to resist an acidic environment, whereas alkaline conditions stimulated high production of long-chained FA. Analysis on FA profile is valuable for the physiological study of V. parahaemolyticus and its rapid identification., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Halophilic archaeal strain R28(T) was isolated from the brown alga Laminaria produced at Dalian, Liaoning Province, China. The cells of the strain were pleomorphic and lysed in distilled water, stained Gram-negative, and formed red-pigmented colonies. Strain R28(T) was able to grow at 25-50 °C (optimum 42 °C), in the presence of 3.1-5.1 M NaCl (optimum 3.9 M NaCl), with 0.005-1.0 M MgCl(2) (optimum 0.01 M MgCl(2)) and at pH 6.0-9.5 (optimum pH 7.0-7.5). The minimal NaCl concentration to prevent cell lysis was 15 % (w/v). The major polar lipids of the strain were identified as phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, and two glycolipids chromatographically identical to those of Halovenus aranensis CGMCC 1.11001(T). The 16S rRNA gene and rpoB' gene of strain R28(T) were phylogenetically related to the corresponding genes of Hvn. aranensis CGMCC 1.11001(T) (91.9-97.2 and 82.9 % nucleotide identity, respectively). The DNA G+C content of strain R28(T) was determined to be 56.3 mol%. The phenotypic, chemotaxonomic, and phylogenetic properties suggest that strain R28(T) (=CGMCC 1.10592(T) = JCM 17269(T)) represents a novel species of the genus Halovenus, for which the name Halovenus rubra sp. nov. is proposed.

Seaweed-associated heterotrophic bacterial communities were screened to isolate potentially useful antimicrobial strains, which were characterized by phylogenetic analysis. The bacteria were screened for the presence of metabolite genes involved in natural product biosynthetic pathway, and the structural properties of secondary metabolites were correlated with the genes. Bioactivity-guided isolation of polyene antibiotic 7-O-methyl-5'-hydroxy-3'-heptenoate-macrolactin from Bacillus subtilis MTCC10403 associated with seaweed Anthophycus longifolius using mass spectrometry and extensive 2D-NMR studies was carried out. The newly isolated macrolactin compound is a bactericidal antibiotic with broad spectrum activity against human opportunistic clinical pathogens. The biosynthetic pathway of 7-O-methyl-5'-hydroxy-3'-heptenoate-macrolactin by means of a stepwise, decarboxylative condensation pathway established the PKS-assisted biosynthesis of the parent macrolactin and the side-chain 5-hydroxyhept-3-enoate moiety attached to the macrolactin ring system at C-7. Antimicrobial activity analysis combined with the results of amplifying genes encoding for polyketide synthetase and nonribosomal peptide synthetase showed that seaweed-associated bacteria had broad-spectrum antimicrobial activity. The present work may have an impact on the exploitation of macrolactins for pharmaceutical and biotechnological applications.

Microbiological quality of laver, one of the edible seaweeds, has not been reported in a real processing line. Laver or supplements were collected from six manufacturers (A to F) to assess potential microbiological hazards and the critical control points in commercial processing lines. Aerobic plate counts (APC), coliform counts, Bacillus cereus, Staphylococcus aureus, and Vibrio parahaemolyticus were enumerated, and the presence of B. cereus, Listeria monocytogenes, Salmonella, S. aureus, and V. parahaemolyticus were confirmed during processing. The raw material, i.e., dried laver, had a high initial APC level (4.4 to 7.8 log CFU/g), which decreased gradually during processing (final products, 1.3 to 5.9 log CFU/g). Coliforms and B. cereus were not detected in any of the final products, but they were present in some raw materials and semiprocessed products in quantitative analysis. After enrichment for recovery of stress-injured cells, E. coli and foodborne pathogens were not detected in any samples, with the exception of B. cereus. Heat-injured and spore-forming B. cereus isolates were occasionally obtained from some of the raw materials and products after enrichment, thus B. cereus may be a potential microbiological hazard that should be controlled using strategic intervention measures. Secondary roasting (260 to 400°C, 2 to 10 s) significantly reduced the APC (maximum log reduction, 4.7 log CFU/g), and this could be a key intervention step for controlling microbiological hazards during processing (critical control point). When this step was performed appropriately, according to the processing guide for each plant, the microorganisms were inactivated more successfully in the products. This study provides scientific evidence that may facilitate the development of strategies for microbiological hazard control and hygienic management guidelines for real manufacturing plants.

A strain designated as S85(T) was isolated from a seaweed collected from coastal area of Chuuk State in Micronesia. The strain was gram-negative, rod-shaped, and non-motile and formed yellow colonies on the SWY agar (0.2 % yeast extract and 1.5 % agar in seawater) and Marine agar 2216. The strain grew at pH 5-9 (optimum, pH 8), at 15-40 °C (optimum, 25-28 °C), and with 1-9 % (w/v) NaCl (optimum, 3 %). The phylogenetic analysis based on 16S rRNA gene sequence showed that strain S85(T) was related to Lutibacter litoralis CL-TF09(T) and Maritimimonas rapanae A31(T) with 91.4 % and with 90.5 % similarity, respectively. The dominant fatty acids were iso-C15:0, iso-C15:0 3-OH and iso-C17:0 3-OH, C16:0 3-OH and summed feature 3 (C16:1 ω7c and/or iso-C15:0 2-OH). The major isoprenoid quinone was MK-6. The DNA G+C content of the type strain was 34.6 mol %. The major polar lipids were phosphatidylethanolamine, an unknown glycolipid and two unknown polar lipids. Based on this polyphasic taxonomic data, strain S85(T) stands for a novel species of a new genus, and we propose the name Ochrovirga pacifica gen. nov., sp. nov. The type strain of O. pacifica is S85(T) (=KCCM 90106 =JCM 18327(T)).

Carotenoids are a class of naturally occurring pigment, carrying out important biological functions in photosynthesis and involved in environmental responses including nutrition in organisms. Saproxanthin and myxol, which have monocyclic carotenoids with a γ-carotene skeleton, have been reported to show a stronger antioxidant activity than those with β-carotene and zeaxanthin. In this research, a yellow-orange bacterium of strain 11shimoA1 (JCM19538) was isolated from a seaweed collected at Nabeta Bay (Shizuoka, Japan). The 16S rRNA gene sequence of strain 11shimoA1 revealed more than 99.99 % similarity with those of Jejuia pallidilutea strains in the family Flavobacteriaceae. Strain 11shimoA1 synthesized two types of carotenoids. One of them was (3R, 3'R)-zeaxanthin with dicyclic structure and another was identified as (3R, 2'S)-2'-isopentenylsaproxanthin, a novel monocyclic carotenoid with pentenyl residue at C-2' position of saproxanthin, using FAB-MS, (1)H NMR, and CD analyses. Culturing strain 11shimoA1 in an alkaline medium at pH 9.2 resulted in a markedly increased in production of 2'-isopentenylsaproxanthin per dry cell weight, but a decreased in zeaxanthin production as compared to their respective production levels in medium with pH 7.0. These carotenoids are likely to play some roles in the adaptation of the bacterium to the environmental conditions.

A metagenomic library was constructed from microorganisms associated with the brown alga Ascophyllum nodosum. Functional screening of this library revealed 13 novel putative esterase loci and two glycoside hydrolase loci. Sequence and gene cluster analysis showed the wide diversity of the identified enzymes and gave an idea of the microbial populations present during the sample collection period. Lastly, an endo-β-1,4-glucanase having less than 50% identity to sequences of known cellulases was purified and partially characterized, showing activity at low temperature and after prolonged incubation in concentrated salt solutions., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

Insights into the diversity of marine natural microbial biofilms, as for example those developing at the surface of marine macroalgae, can be obtained by using molecular techniques based on 16S rRNA genes. We applied denaturing gradient gel electrophoresis (DGGE) with 16S rRNA genes-specific primers for Planctomycetes to compare the communities of these organisms developing on six different macroalgae (Chondrus crispus, Fucus spiralis, Mastocarpus stellatus, Porphyra dioica, Sargassum muticum, and Ulva sp.) sampled in spring 2012 in two rocky beaches in the north of Portugal. Planctomycetes can be one of the dominant organisms found in the epibacterial community of macroalgae, and we wanted to determine the degree of specificity and the spatial variation of these group. Shannon diversity indexes obtained from the comparison of DGGE profiles were similar in all the macroalgae, and in both sites, F. spiralis was the algae presenting lower Planctomycetes diversity, while M. stellatus and P. dioica from Porto showed the highest diversity. The analysis of DGGE profiles, including anosim statistics, indicate the existence of a specific Planctomycetes community associated with the algal host, likely independent of geographical variation. Sequencing of DGGE bands indicated that Planctomycetes communities were highly diverse, and some Operational Taxonomic Units seemed to be specifically associated with each macroalgae., (© 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.)

The current study investigated the synergistic effects of NaOCl (50-200 ppm)/ultrasound (37 kHz, 380 W for 5-100 min) combination on the reduction of Escherichia coli and Bacillus cereus in raw laver. The synergistic reductions were not dependent on concentrations of NaOCl and times of ultrasound. Synergistic reduction ranged from 0.1 to 0.5 log10 colony-forming units (CFU)/g and 0.1-1.1 log10 CFU/g, respectively, for E. coli and B. cereus, with the largest synergistic reduction in the combination of 200 ppm NaOCl and 60-min ultrasound. Moreover, significant differences of "L" (lightness), "a" (redness), and "b" (yellowness) were not observed in combined with 50-200 ppm NaOCl and 100-min ultrasound compared to those in raw laver treated by only 100-min ultrasound. The results in the current study indicate that the combined treatment of 200 ppm NaOCl and 60-min ultrasound could be regarded a potential optimum hurdle approach in the seaweed production, processing, and distribution process to enhance seaweed safety.

Seaweed-associated bacteria play a crucial role in morphogenesis and growth of seaweeds (macroalgae) in direct and/or indirect ways. Bacterial communities belonging to the phyla Proteobacteria and Firmicutes are generally the most abundant on seaweed surfaces. Associated bacterial communities produce plant growth-promoting substances, quorum sensing signalling molecules, bioactive compounds and other effective molecules that are responsible for normal morphology, development and growth of seaweeds. Also, bioactive molecules of associated bacteria determine the presence of other bacterial strains on seaweeds and protect the host from harmful entities present in the pelagic realm. The ecological functions of cross-domain signalling between seaweeds and bacteria have been reported as liberation of carpospores in the red seaweeds and settlement of zoospores in the green seaweeds. In the present review, the role of extracellular polymeric substances in growth and settlement of seaweeds spores is also highlighted. To elucidate the functional roles of associated bacteria and the molecular mechanisms underlying reported ecological phenomena in seaweeds requires a combined ecological, microbiological and biochemical approach., (© 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.)

Twenty two strains of Rhodopirellula were isolated from the epiphytic community of several marine macroalgae and separated into two groups, designated as group B and group C. In this study, we characterized these groups as two novel species belonging to the genus Rhodopirellula. These strains were represented by pleomorphic cells that were arranged in rosettes and formed pink- or red-pigmented colonies. The organisms were chemoorganotrophic and required vitamin B12 for growth. Their optimal temperature for growth was around 25°C. Major fatty acids were C18:1 ω9c, C16:0 and C16:1 ω7c/C16:1 ω6c. Phosphatidylcholine and phosphatidylglycerol were the major polar lipids. Unidentified phospholipids were also present. The 16S rDNA sequence analysis confirmed the affiliation of these organisms to the order Planctomycetales, genus Rhodopirellula, with R. baltica as the closest phylogenetic relative. The analysis of a partial sequence of the gene encoding the β-subunit of RNA polymerase (rpoB) confirmed the phylogenetic separation of the isolates into two different species of the genus Rhodopirellula. The 16S rRNA sequences from strains of group B revealed their widespread occurrence across the world, whereas strains of group C were not observed before. On the basis of physiological, biochemical, chemotaxonomic and genetic characteristics we propose that our isolates represent two new species of Rhodopirellula, Rhodopirellula rubra sp. nov. (type strain is LF2(T)=DSM 25,459=CECT 8075) and Rhodopirellula lusitana sp. nov. (type strain is UC17(T)=DSM 25,457=LMG 27,777)., (Copyright © 2014. Published by Elsevier GmbH.)

Six antimicrobial-producing seaweed-derived Bacillus strains were evaluated in vitro as animal probiotics, in comparison to two Bacillus from an EU-authorized animal probiotic product. Antimicrobial activity was demonstrated on solid media against porcine Salmonella and E. coli. The marine isolates were most active against the latter, had better activity than the commercial probiotics and Bacillus pumilus WIT 588 also reduced E. coli counts in broth. All of the marine Bacillus tolerated physiological concentrations of bile, with some as tolerant as one of the probiotics. Spore counts for all isolates remained almost constant during incubation in simulated gastric and ileum juices. All of the marine Bacillus grew anaerobically and the spores of all except one isolate germinated under anaerobic conditions. All were sensitive to a panel of antibiotics and none harbored Bacillus enterotoxin genes but all, except B. pumilus WIT 588, showed some degree of β-hemolysis. However, trypan blue dye exclusion and xCELLigence assays demonstrated a lack of toxicity in comparison to two pathogens; in fact, the commercial probiotics appeared more cytotoxic than the majority of the marine Bacillus. Overall, some of the marine-derived Bacillus, in particular B. pumilus WIT 588, demonstrate potential for use as livestock probiotics.

Marine microorganisms play key roles in every marine ecological process, hence the growing interest in studying their populations and functions. Microbial communities on algae remain underexplored, however, despite their huge biodiversity and the fact that they differ markedly from those living freely in seawater. The study of this microbiota and of its relationships with algal hosts should provide crucial information for ecological investigations on algae and aquatic ecosystems. Furthermore, because these microorganisms interact with algae in multiple, complex ways, they constitute an interesting source of novel bioactive compounds with biotechnological potential, such as dehalogenases, antimicrobials, and alga-specific polysaccharidases (e.g., agarases, carrageenases, and alginate lyases). Here, to demonstrate the huge potential of alga-associated organisms and their metabolites in developing future biotechnological applications, we first describe the immense diversity and density of these microbial biofilms. We further describe their complex interactions with algae, leading to the production of specific bioactive compounds and hydrolytic enzymes of biotechnological interest. We end with a glance at their potential use in medical and industrial applications.

Macroalgae are important ecosystem engineers in temperate marine waters. The function of macroalgae is intimately linked to the composition and structure of their epibiotic bacterial, communities, and evidence has emerged that bacteria can also have a negative impact on their host by causing disease. A few examples exist where bacteria have been unambiguously linked to macroalgal disease, however in many cases, pathogenicity has not been clearly separated from saprophytic behaviour or secondary colonization after disease initiation. Nevertheless, pathogenic pressure by bacteria might be substantial, as macroalgae have evolved a range of innate and induced defence mechanism that have the potential to control bacterial attacks. The presence and abundance of virulence factors in marine bacteria, which have not previously been recognized as pathogens, also represents an underappreciated, opportunistic potential for disease. Given that virulence expression in opportunistic pathogens is often dependent on environmental conditions, we predict that current and future anthropogenic changes in the marine environment will lead to an increase in the occurrence of macroalgal disease. This review highlights important areas of research that require future attention to understand the link between environmental change, opportunistic pathogens and macroalgal health in the world's oceans., (© 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.)

In order to explore marine microorganisms with pharmaceutical potential, marine bacteria, collected from different coastal areas of the Moroccan Atlantic Ocean, were previously isolated from seawater, sediment, marine invertebrates and seaweeds. The antimicrobial activities of these microorganisms were investigated against the pathogens involved in human pathologies. Whole cultures of 34 marine microorganisms were screened for antimicrobial activities using the method of agar diffusion against three Gram-positive bacteria, two Gram-negative bacteria, and against yeast. The results showed that among the 34 isolates studied, 28 (82%) strains have antimicrobial activity against at least one pathogen studied, 11 (32%) strains have antifungal activity and 24 (76%) strains are active against Gram-positive bacteria, while 21 (62%) strains are active against Gram-negative bacteria. Among isolates having antimicrobial activity, 14 were identified and were assigned to the genera Acinetobacter, Aeromonas, Alcaligenes, Bacillus, Chromobacterium, Enterococcus, Pantoea and Pseudomonas. Due to a competitive role for space and nutrient, the marine microorganisms can produce antibiotic substance; therefore, these marine microorganisms were expected to be potential resources of natural antibiotic products., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

The genomes of three Rhodopirellula baltica strains were sequenced as permanent drafts to complement the full genome sequence of the type strain R. baltica SH1(T). The isolates are part of a larger study to infer the biogeography of Rhodopirellula species in European marine waters, as well as to amend the genus description of R. baltica. This genomics resource article is the first of a series of five publications reporting in total eight new permanent daft genomes of Rhodopirellula species., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The genome of Rhodopirellula rubra strain SWK7 was sequenced as a permanent draft to complement the full genome sequence of the type strain Rhodopirellula baltica SH1(T). This isolate is part of a larger study to infer the biogeography of Rhodopirellula species in European marine waters, as well as to amend the genus description of R. baltica. This genomics resource article is the fourth among a series of five publications reporting in a total of eight new permanent draft genomes of Rhodopirellula species., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Increased anthropogenic CO2 emissions are expected to cause a drop in oceanic pH of c. 0.4 units within this century. According to current assessments, the consequences of this are limited for oceanic Cyanobacteria, and absent for viruses. We investigated the effect of pH on the life history of cyanophage S-PM2 and its host, Synechococcus sp. WH7803, at current pH concentrations and at predicted future concentrations. We identified significant negative effects of decreasing pH on Synechococcus growth rate, with profound negative implications for S-PM2 biogenesis and its infection cycle. The duration of the S-PM2 eclipse period increased significantly with decreasing pH. In contrast, the latent period was shorter at pH 7.6 than at pH 8, coinciding with a reduction in S-PM2 burst size from 20.1 ± 3.2 progeny phages per cell at pH 8 to 5.68 ± 4.4 progeny phages per cell at pH 7.6. At pH 7, there was no detectable progeny release. The extracellular stage of S-PM2 was insensitive to pH changes, but sensitive to light, with significant loss in infectivity (0.35-0.38 day(-1) ) at relatively low irradiances (> 130 μmol photon m(-2) s(-1) ). Overall, the results suggest that pH has significant influence on cyanobacterial growth with important implications for the interactions between Cyanobacteria and their viruses., (© 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.)

A Gram-stain-negative, non-motile and aerobic bacterium, designated CF17(T), was isolated from coastal planktonic seaweeds, East China Sea. The isolate grew at 18-37 °C (optimum 25-28 °C), pH 6.5-9.0 (optimum 7.0-8.0) and with 0-5 % NaCl (optimum 1-2 %, w/v) and 0.5-10 % sea salts (optimum 2-3 %, w/v). Growth of strain CF17(T) could be stimulated prominently by supplementing the growth medium with the autoclaved supernatant of a culture of strain CF5, which was isolated from the same sample along with strain CF17(T). The cell morphology of strain CF17(T) was a bean-shaped rod consisting of a swollen end and a long prostheca. The phylogenetic analysis of 16S rRNA gene sequences indicated that strain CF17(T) clustered with Gemmobacter nectariphilus DSM 15620(T) within the genus Gemmobacter. The DNA G+C content of strain CF17(T) was 61.4 mol%. The respiratory quinone was ubiquinone Q-10. The major fatty acids included C18 : 1ω7c and C18 : 0. The polar lipids of strain CF17(T) consisted of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, two uncharacterized phospholipids, one uncharacterized aminolipid, three uncharacterized glycolipids and one uncharacterized lipid. On the basis of phenotypic, phylogenetic and chemotaxonomic data, strain CF17(T) ( = CGMCC 1.11024(T) = JCM 18498(T)) is considered to represent a novel species of the genus Gemmobacter, for which the name Gemmobacter megaterium sp. nov. is proposed.

Four chlorinated depsidones (two reported for the second time (1 and 2) and two known (3 and 4)) were isolated from a seaweed-derived Aspergillus unguis strain. Their structures were spectroscopically elucidated. Compounds 1, 3 and 4 strongly inhibited methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentrations (MICs) of 2, 2 and 4 μg/mL and killed Artemia larva with LC50 of 4.1, 1.7 and 2.8 μg/mL, respectively. Besides, in DNA-damaging test, they also selectively inhibited a DNA repair capacity-defective Escherichia coli strain AB3027(-) (MICs: 2, 32 and 4 μg/mL, respectively) compared with the wild-type strain AB1157(+) (MICs: over 512, over 512 and 256 μg/mL, respectively). Furthermore, compound 1 also strongly inhibited cancer cell line A-549 (IC50: 0.5 μg/mL). The above-mentioned bioactivities were newly reported for compound 1. In contrast, compound 2 did not exhibit significant activity. The structure-activity relationship indicated that a complete lactone ring may be important.

As part of a proactive approach to environmental protection, emerging issues with potential impact on the environment is the subject of ongoing investigation. One emerging area of environmental research concerns pharmaceuticals like salicylic acid, which is the main metabolite of various analgesics including aspirin. It is a common component of sewage effluent and also an intermediate in the degradation pathway of various aromatic compounds which are introduced in the marine environment as pollutants. In this study, biotransformation products of salicylic acid by seaweed, Bryopsis plumosa, associated marine bacterium, Moraxella spp. MB1, have been investigated. Phenol, conjugates of phenol and hydroxy cinnamic acid derivatives (coumaroyl, caffeoyl, feruloyl and trihydroxy cinnamyl) with salicylic acid (3-8) were identified as the bioconversion products by electrospray ionization mass spectrometry. These results show that the microorganism do not degrade phenolic acid but catalyses oxygen dependent transformations without ring cleavage. The degradation of salicylic acid is known to proceed either via gentisic acid pathway or catechol pathway but this is the first report of biotransformation of salicylic acid into cinnamates, without ring cleavage. Besides cinnamic acid derivatives (9-12), metabolites produced by the bacterium include antimicrobial indole (13) and β-carbolines, norharman (14), harman (15) and methyl derivative (16), which are beneficial to the host and the environment.

Global climate change is expected to alter the Arctic bioregion markedly in coming decades. As a result, monitoring of the expected and actual changes has assumed high scientific significance. Many marine science objectives are best supported with the use of scientific diving techniques. Some important keystone environments are located in extremely remote locations where land-based expeditions offer high flexibility and cost-effectiveness over ship-based operations. However, the extreme remoteness of some of these locations, coupled with complex and unreliable land, sea and air communications, means that there is rarely quick access (< 48 h) to any specialized diving medical intervention or recompression. In 2009, a land based expedition to the north end of Baffin Island was undertaken with the specific aim of establishing an inventory of the diversity of seaweeds and their pathogens that was broadly representative of a high Arctic marine environment. This account highlights some of the logistical considerations taken on that expedition; specifically it outlines the non-recompression treatment pathway that would have been adopted in the event of a diver suffering decompression illness.

Epibionts from the red (Hypnea valentiae) and brown seaweeds (Padina tetrastromatica) were rapidly isolated on Zobell agar medium. All the isolates from both the seaweeds (76 numbers) were tested against five human pathogens which were resistant to at least one of the commercially available antibiotics at a minimal concentration of 10 mg. The most antibiotic productive isolate (PT19) from Padina tetrastromatica was extracted and observed to inhibit Klebsiella pneumoniae and Pseudomonas aeruginosa with zone sizes of 15 and 10 mm radius, respectively, at a concentration of 300 μg. Further, a direct bioautography was done and an inhibition was witnessed against the aforementioned pathogens even at 2 μg concentration around three spots (R f values 0.6, 0.7, and 0.8). Preparative thin-layer chromatography yielded a yellow sticky compound (6 mg) which was identified as an alkaloid. The compound on reversed-phase high-pressure liquid chromatography analysis yielded two major and two minor peaks with retention times, 3.1, 4.2, 4.7, and 4.9 min, respectively. The antibacterial compound was recorded 96.6 % pure, and the producer strain was identified as Pseudomonas sp. To our knowledge, we are the first to isolate and identify Pseudomonas from Padina tetrastromatica producing antibacterial alkaloids. This study will pave way for exploring more bacterial load from the said algal groups for bioactivities.

A novel halophilic alginate-degrading microorganism was isolated from rotten seaweed and identified as Isoptericola halotolerans CGMCC5336. The lyase from the strain was purified to homogeneity by combining of ammonium sulfate fractionation and anion-exchange chromatography with a specific activity of 8409.19 U/ml and a recovery of 25.07%. This enzyme was a monomer with a molecular mass of approximately 28 kDa. The optimal temperature and pH were 50 °C and pH 7.0, respectively. The lyase maintained stability at neutral pH (7.0-8.0) and temperatures below 50 °C. Metal ions including Na(+), Mg(2+), Mn(2+), and Ca(2+) notably increased the activity of the enzyme. With sodium alginate as the substrate, the Km and Vmax were 0.26 mg/ml and 1.31 mg/ml min, respectively. The alginate lyase had substrate specificity for polyguluronate and polymannuronate units in alginate molecules, indicating its bifunctionality. These excellent characteristics demonstrated the potential applications in alginate oligosaccharides production with low polymerisation degrees., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Unlabelled: Hypnea musciformis red seaweed is popularly known to produce carrageenan was collected from the Gulf of Mannar, India. Strain HMGM-7 [MTCC 11712] was isolated from the surface of this seaweed, which was capable of producing an extracellular black-coloured polymeric pigment. Based on phenotypic characterization and 16S rDNA sequencing, the strain HMGM-7 was identified as Pseudomonas stutzeri. Biophysical characterization by UV-visible, FT-IR, EPR and XRD spectroscopic studies confirmed the pigment as melanin. Further chemical characterization showed that it was acid-resistant, alkali-soluble and alkali-insoluble in most of the organic solvents and distilled water. To our knowledge, this is a first report on a marine Pseudomonas stutzeri strain producing significant amounts of melanin of about 6·7 g l(-1) without L-tyrosine supplementation in the sea-water production medium., Significance and Impact of the Study: This investigation reports a marine Pseudomonas stutzeri strain HMGM-7 [MTCC 11712] that produces significant quantities of melanin (6·7 g l(-1) ) in sea-water medium without the supplementation of L-tyrosine. The confirmation of the produced melanin was carried out by various chemical and physical characterization studies. The isolated melanin may find potential application for use in cosmetic and/or pharmaceutical industries., (© 2013 The Society for Applied Microbiology.)

An aerobic, Gram-stain-negative, short rod-shaped, non-motile and non-sporulating bacterium, designed strain 8-1b(T), was isolated from seaweed collected from the intertidal zone of Zhoushan sea area, East China Sea. Strain 8-1b(T) grew at 4-39 °C (optimum, 28-32 °C) and at pH 6.0-9.5 (optimum, 7.0-8.5), and with 0.5-8% (w/v) NaCl (optimum, 1-3%) and 0.5-10% (w/v) sea salts (optimum, 2-3%). Analysis of 16S rRNA gene sequences revealed that strain 8-1b(T) was related closely to Aequorivita capsosiphonis JCM 15070(T) (96.7% similarity). The DNA G+C content of strain 8-1b(T) was 36.6 mol%. Compared with reference strains, cells of strain 8-1b(T) showed positive activities for H₂S production and utilization of D-mannose, DL-lactic acid, L-asparagine and glycyl L-aspartic acid. The major fatty acids of strain 8-1b(T) were iso-C(15:0), iso-C(17:0) 3-OH, iso-C(15:1) G and iso-C(17:1)ω9c. The main respiratory quinone was menaquinone 6. The polar lipids of strain 8-1b(T) consisted of phosphatidylethanolamine (PE), three uncharacterized aminolipids (AL1-3), four uncharacterized glycolipids (GL1-4) and five uncharacterized lipids (L1-5). Based on the phenotypic and genotypic characterization, strain 8-1b(T) represents a novel species of the genus Aequorivita, for which the name Aequorivita viscosa sp. nov. is proposed. The type strain is strain 8-1b(T) ( =CGMCC 1.11023(T) = JCM 18497(T)). Emended descriptions of Aequorivita antarctica and Aequorivita capsosiphonis are also presented.

Benthic algae are associated with coral death in the form of stress and disease. It's been proposed that they release exudates, which facilitate invasion of potentially pathogenic microbes at the coral-algal interface, resulting in coral disease. However, the original source of these pathogens remains unknown. This study examined the ability of benthic algae to act as reservoirs of coral pathogens by characterizing surface associated microbes associated with major Caribbean and Indo-Pacific algal species/types and by comparing them to potential pathogens of two dominant coral diseases: White Syndrome (WS) in the Indo-Pacific and Yellow Band Disease (YBD) in the Caribbean. Coral and algal sampling was conducted simultaneously at the same sites to avoid spatial effects. Potential pathogens were defined as those absent or rare in healthy corals, increasing in abundance in healthy tissues adjacent to a disease lesion, and dominant in disease lesions. Potentially pathogenic bacteria were detected in both WS and YBD and were also present within the majority of algal species/types (54 and 100% for WS and YBD respectively). Pathogenic ciliates were associated only with WS and not YBD lesions and these were also present in 36% of the Indo-Pacific algal species. Although potential pathogens were associated with many algal species, their presence was inconsistent among replicate algal samples and detection rates were relatively low, suggestive of low density and occurrence. At the community level, coral-associated microbes irrespective of the health of their host differed from algal-associated microbes, supporting that algae and corals have distinctive microbial communities associated with their tissue. We conclude that benthic algae are common reservoirs for a variety of different potential coral pathogens. However, algal-associated microbes alone are unlikely to cause coral death. Initial damage or stress to the coral via other competitive mechanisms is most likely a prerequisite to potential transmission of these pathogens.

We surveyed the distribution and diversity of fungi associated with eight macroalgae from Antarctica and their capability to produce bioactive compounds. The collections yielded 148 fungal isolates, which were identified using molecular methods as belonging to 21 genera and 50 taxa. The most frequent taxa were Geomyces species (sp.), Penicillium sp. and Metschnikowia australis. Seven fungal isolates associated with the endemic Antarctic macroalgae Monostroma hariotii (Chlorophyte) displayed high internal transcribed spacer sequences similarities with the psychrophilic pathogenic fungus Geomyces destructans. Thirty-three fungal singletons (66%) were identified, representing rare components of the fungal communities. The fungal communities displayed high diversity, richness and dominance indices; however, rarefaction curves indicated that not all of the fungal diversity present was recovered. Penicillium sp. UFMGCB 6034 and Penicillium sp. UFMGCB 6120, recovered from the endemic species Palmaria decipiens (Rhodophyte) and M. hariotii, respectively, yielded extracts with high and selective antifungal and/or trypanocidal activities, in which a preliminary spectral analysis using proton nuclear magnetic resonance spectroscopy indicated the presence of highly functionalised aromatic compounds. These results suggest that the endemic and cold-adapted macroalgae of Antarctica shelter a rich, diversity and complex fungal communities consisting of a few dominant indigenous or mesophilic cold-adapted species, and a large number of rare and/or endemic taxa, which may provide an interesting model of algal-fungal interactions under extreme conditions as well as a potential source of bioactive compounds.

A Gram-stain-negative, non-spore-forming, strictly aerobic, orange-pigmented bacterial strain, motile by gliding, designated CAU 1044(T), was isolated from a green seaweed and its taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CAU 1044(T) formed a distinct lineage within the genus Maribacter and was most closely related to Maribacter antarcticus JCM 15445(T) and Maribacter arcticus KOPRI 20941(T) (96.3 and 95.7 % similarity, respectively). Strain CAU 1044(T) contained menaquinone 6 as the only isoprenoid quinone and iso-C15 : 0, summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c and/or iso-C15 : 0 2-OH), iso-C17 : 0 3-OH and iso-C15 : 1 G as the major fatty acids. The cell wall peptidoglycan of strain CAU 1044(T) contained meso-diaminopimelic acid and the major whole-cell sugars were glucose and ribose. The polar lipids were composed of phosphatidylethanolamine, one unidentified phospholipid, six unidentified aminolipids and four unidentified lipids. The DNA G+C content was 40.2 mol%. On the basis of phenotypic data and phylogenetic inference, strain CAU 1044(T) should be classified as a representative of a novel species in the genus Maribacter for which the name Maribacter chungangensis sp. nov. is proposed. The type strain is CAU 1044(T) ( = KCTC 23735(T) = CCUG 61948(T)). Emended descriptions of the genus Maribacter and the species M. arcticus KCTC 22053(T) are also proposed.

A total of 16 marine strains belonging to the genus Arenibacter, recovered from diverse microbial communities associated with various marine habitats and collected from different locations, were evaluated in degradation of natural polysaccharides and chromogenic glycosides. Most strains were affiliated with five recognized species, and some presented three new species within the genus Arenibacter. No strains contained enzymes depolymerizing polysaccharides, but synthesized a wide spectrum of glycosidases. Highly active β-N-acetylglucosaminidases and α-N-acetylgalactosaminidases were the main glycosidases for all Arenibacter. The genes, encoding two new members of glycoside hydrolyses (GH) families, 20 and 109, were isolated and characterized from the genomes of Arenibacter latericius. Molecular genetic analysis using glycosidase-specific primers shows the absence of GH27 and GH36 genes. A sequence comparison with functionally-characterized GH20 and GH109 enzymes shows that both sequences are closest to the enzymes of chitinolytic bacteria Vibrio furnissii and Cellulomonas fimi of marine and terrestrial origin, as well as human pathogen Elisabethkingia meningoseptica and simbionts Akkermansia muciniphila, gut and non-gut Bacteroides, respectively. These results revealed that the genus Arenibacter is a highly taxonomic diverse group of microorganisms, which can participate in degradation of natural polymers in marine environments depending on their niche and habitat adaptations. They are new prospective candidates for biotechnological applications due to their production of unique glycosidases.

The siphonous green seaweed Bryopsis harbors complex intracellular bacterial communities. Previous studies demonstrated that certain species form close, obligate associations with Flavobacteriaceae. A predominant imprint of host evolutionary history on the presence of these bacteria suggests a highly specialized association. In this study we elaborate on previous results by expanding the taxon sampling and testing for host-symbiont coevolution Therefore, we optimized a PCR protocol to directly and specifically amplify Flavobacteriaceae endosymbiont 16S rRNA gene sequences, which allowed us to screen a large number of algal samples without the need for cultivation or surface sterilization. We analyzed 146 Bryopsis samples, and 92 additional samples belonging to the Bryopsidales and other orders within the class Ulvophyceae. Results indicate that the Flavobacteriaceae endosymbionts are restricted to Bryopsis, and only occur within specific, warm-temperate and tropical clades of the genus. Statistical analyses (AMOVA) demonstrate a significant non-random host-symbiont association. Comparison of bacterial 16S rRNA and Bryopsis rbcL phylogenies, however, reveal complex host-symbiont evolutionary associations, whereby closely related hosts predominantly harbor genetically similar endosymbionts. Bacterial genotypes are rarely confined to a single Bryopsis species and most Bryopsis species harbored several Flavobacteriaceae, obscuring a clear pattern of coevolution., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Aim of this study was to evaluate the antagonistic potential of epibiotic bacteria from seaweeds, Ulva lactuca, Dictyota dichotoma and Padina tetrastromatica against some potent human pathogens. The epibiotic bacteria of Ulva lactuca shows higher level of inhibition properties than the other species. The strain UL1 shows broad spectrum inhibitory activity against 7 pathogens. The inhibitory level of epibiotic bacteria ranged from low to moderate activity. The present investigation suggests that the epibiotic bacteria are good source for the isolation of antibacterial compounds of biomedical importance. The compounds can further be purified and can used to save mankind from dreadful diseases.

Seaweeds (macroalgae) form a diverse and ubiquitous group of photosynthetic organisms that play an essential role in aquatic ecosystems. These ecosystem engineers contribute significantly to global primary production and are the major habitat formers on rocky shores in temperate waters, providing food and shelter for aquatic life. Like other eukaryotic organisms, macroalgae harbor a rich diversity of associated microorganisms with functions related to host health and defense. In particular, epiphytic bacterial communities have been reported as essential for normal morphological development of the algal host, and bacteria with antifouling properties are thought to protect chemically undefended macroalgae from detrimental, secondary colonization by other microscopic and macroscopic epibiota. This tight relationship suggests that macroalgae and epiphytic bacteria interact as a unified functional entity or holobiont, analogous to the previously suggested relationship in corals. Moreover, given that the impact of diseases in marine ecosystems is apparently increasing, understanding the role of bacteria as saprophytes and pathogens in seaweed communities may have important implications for marine management strategies. This review reports on the recent advances in the understanding of macroalgal-bacterial interactions with reference to the diversity and functional role of epiphytic bacteria in maintaining algal health, highlighting the holobiont concept., (© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)

Increasing algal cover on tropical reefs worldwide may be maintained through feedbacks whereby algae outcompete coral by altering microbial activity. We hypothesized that algae and coral release compositionally distinct exudates that differentially alter bacterioplankton growth and community structure. We collected exudates from the dominant hermatypic coral holobiont Porites spp. and three dominant macroalgae (one each Ochrophyta, Rhodophyta and Chlorophyta) from reefs of Mo'orea, French Polynesia. We characterized exudates by measuring dissolved organic carbon (DOC) and fractional dissolved combined neutral sugars (DCNSs) and subsequently tracked bacterioplankton responses to each exudate over 48 h, assessing cellular growth, DOC/DCNS utilization and changes in taxonomic composition (via 16S rRNA amplicon pyrosequencing). Fleshy macroalgal exudates were enriched in the DCNS components fucose (Ochrophyta) and galactose (Rhodophyta); coral and calcareous algal exudates were enriched in total DCNS but in the same component proportions as ambient seawater. Rates of bacterioplankton growth and DOC utilization were significantly higher in algal exudate treatments than in coral exudate and control incubations with each community selectively removing different DCNS components. Coral exudates engendered the smallest shift in overall bacterioplankton community structure, maintained high diversity and enriched taxa from Alphaproteobacteria lineages containing cultured representatives with relatively few virulence factors (VFs) (Hyphomonadaceae and Erythrobacteraceae). In contrast, macroalgal exudates selected for less diverse communities heavily enriched in copiotrophic Gammaproteobacteria lineages containing cultured pathogens with increased VFs (Vibrionaceae and Pseudoalteromonadaceae). Our results demonstrate that algal exudates are enriched in DCNS components, foster rapid growth of bacterioplankton and select for bacterial populations with more potential VFs than coral exudates.

Microbial fermentation is a promising technology for hydrogen (H(2)) production. H(2) producers in marine geothermal environments are thermophilic and halotolerant. However, no one has surveyed an environment specifically for thermophilic bacteria that produce H(2) through Fe-Fe hydrogenases (H(2)ase). Using heterotrophic medium, several microflora from a seaweed bed associated with marine hot springs were enriched and analyzed for H(2) production. A H(2)-producing microflora was obtained from Sargassum sp., 16S rRNA genes and Fe-Fe H(2)ase diversities of this enrichment were also analyzed. Based on 16S rRNA genes analysis, 10 phylotypes were found in the H(2)-producing microflora showing 90.0-99.5 % identities to known species, and belonged to Clostridia, Gammaproteobacteria, and Bacillales. Clostridia were the most abundant group, and three Clostridia phylotypes were most related to known H(2) producers such as Anaerovorax odorimutans (94.0 % identity), Clostridium papyrosolvens (98.4 % identity), and Clostridium tepidiprofundi (93.1 % identity). For Fe-Fe H(2)ases, seven phylotypes were obtained, showing 63-97 % identities to known Fe-Fe H(2)ases, and fell into four distinct clusters. Phylotypes HW55-3 and HM55-1 belonged to thermophilic and salt-tolerant H(2)-producing Clostridia, Halothermothrix orenii-like Fe-Fe H(2)ases (80 % identity), and cellulolytic H(2)-producing Clostridia, C. papyrosolvens-like Fe-Fe H(2)ases (97 % identity), respectively. The results of both 16S rRNA genes and Fe-Fe H(2)ases surveys suggested that the thermophilic and halotolerant H(2)-producing microflora in seaweed bed of hot spring area represented previously unknown H(2) producers, and have potential application for H(2) production.

The macroalga Fucus vesiculosus carries a specific community of surface bacteria. To identify chemical compounds that possibly mediate abundance and community composition of algae-associated bacteria, we tested the effect of surface-available algal compounds on bacterial settlement and community composition under field conditions. Compounds on algal thalli were separated from the surface by extraction with organic solvents and investigated on growth inhibition and settlement of bacterial isolates. Based on in vitro data, partially purified extract fractions were then exposed to bacterial colonizers in vivo followed by bacterial enumeration and community analysis. The polar fraction of the algal surface extract revealed a significant profouling effect for Vibrionales, whereas the nonpolar fraction - containing the xanthophyll pigment fucoxanthin and other unidentified nonpolar surface compounds - revealed a significant 80% reduction of surface colonizing bacteria. The analysis of bacterial surface communities by 454 pyrosequencing demonstrated that the antifouling activity of nonpolar algal surface compounds was targeting the abundance of natural bacterial colonizers rather than the relative composition of bacterial members within the community. Moreover, the bacterial community composition on F. vesiculosus was markedly different from artificial control substrates and chemically manipulated experimental treatments, suggesting that other, nonextractable surface features and/or physical properties render algal-specific epiphytic bacterial communities., (© 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)

Sea wrack (dislodged sea grasses and seaweeds) was used in biogas production. Fresh water scarcity in island communities where sea wrack could accumulate led to seawater utilization as liquid substrate. Three microbial seeds cow manure (CM), marine sediment (MS), and sea wrack-associated microflora (SWA) were explored for biogas production. The average biogas produced were 2172±156 mL (MS), 1223±308 mL (SWA) and 551±126 mL (CM). Though methane potential (396.9 mL(CH4) g(-1) volatile solid) computed from sea wrack proximate values was comparable to other feedstocks, highest methane yield was low (MS=94.33 mL(CH4) g(-1) VS). Among the microbial seeds, MS proved the best microbial source in utilizing sea wrack biomass and seawater. However, salinity (MS=42‰) observed exceeded average seawater salinity (34‰). Hence, methanogenic activity could have been inhibited. This is the first report on sea wrack biomass utilization for thalassic biogas production., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The thallus surface of the brown macroalga Fucus vesiculosus is covered by a specific biofilm community. This biofilm supposedly plays an important role in the interaction between host and environment. So far, we know little about compositional or functional shifts of this epibiotic bacterial community under changing environmental conditions. In this study, the response of the microbiota to different temperatures with respect to cell density and community composition was analyzed by nonculture-based methods (denaturing gradient gel electrophoresis and 454 pyrosequencing of the 16S rRNA gene). Redundancy analysis showed that despite high variability among host individuals temperature accounted for 20% of the variation in the bacterial community composition, whereas cell density did not differ between groups. Across all samples, 4341 bacterial operational taxonomic units (OTUs) at a 97% similarity level were identified. Eight percent of OTUs were significantly correlated with low, medium, and high temperatures. Notably, the family Rhodobacteraceae increased in relative abundance from 20% to 50% with increasing temperature. OTU diversity (evenness and richness) was higher at 15 °C than at the lower and higher temperatures. Considering their known and presumed ecological functions for the host, change in the epibacterial community may entail shifts in the performance of the host alga., (© 2013 The Authors. Published by Blackwell Publishing Ltd.)

Marine macroalgae are known to harbor large populations of microbial symbionts, and yet, microbe symbiosis in invasive macroalgae remains largely unknown. In this study, we applied molecular methods to study microbial communities associated with two invasive algae Acanthophora spicifera and Gracilaria salicornia and the two native algae Gracilaria coronopifolia and Laurencia nidifica at spatial and temporal scales in Hawaiian coral reef ecosystems. Bacterial communities of both the invasive and native macroalgae displayed little spatial and temporal variations, suggesting consistent and stable bacterial associations with these macroalgae. Results of this study identified three types of bacterial populations: nonspecific (present in both algal and water samples); algae-specific (found in all algal species); and species-specific (only found in individual species). The bacterial diversity of invasive algae was lower than that of their native counterparts at phylum and species levels. Notably, the vast majority (71 %) of bacterial communities associated with the invasive algae G. salicornia were representatives of Cyanobacteria, suggesting a potential ecological significance of symbiotic Cyanobacteria.

The ecological interaction between microorganisms and seaweeds depends on the production of secondary compounds that can influence microbial diversity in the water column and the composition of reef environments. We adapted the (3)H-leucine incorporation technique to measure bacterial activity in biofilms associated with the blades of the macroalgae Sargassum spp. We evaluated (1) if the epiphytic bacteria on the blades were more active in detritus or in the biofilm, (2) substrate saturation and linearity of (3)H-leucine incorporation, (3) the influence of specific metabolic inhibitors during (3)H-leucine incorporation under the presence or absence of natural and artificial light, and (4) the efficiency of radiolabeled protein extraction. Scanning electron microscopy showed heterogeneous distribution of bacteria, diatoms, and polymeric extracellular secretions. Active bacteria were present in both biofilm and detritus on the blades. The highest (3)H-leucine incorporation was obtained when incubating blades not colonized by macroepibionts. Incubations done under field conditions reported higher (3)H-leucine incorporation than in the laboratory. Light quality and sampling manipulation seemed to be the main factors behind this difference. The use of specific metabolic inhibitors confirmed that bacteria are the main group incorporating (3)H-leucine but their association with primary production suggested a symbiotic relationship between bacteria, diatoms, and the seaweed.

This research evaluated biogas production in batch and UASB reactors from pilot-scale acid catalysed steam pretreated and enzymatic hydrolysed wheat straw. The results showed that the pretreatment was efficient and, a sugar yield of 95% was obtained. The pretreatment improved the methane yield (0.28 m(3)/kg VS(added)) by 57% compared to untreated straw. Treatment of the straw hydrolysate with nutrient supplementation in a UASB reactor resulted in a high methane production rate, 2.70 m(3)/m(3).d at a sustainable OLR of 10.4 kg COD/m(3).d and with a COD reduction of 94%. Alternatively, co-digestion of the straw and seaweed hydrolysates in a UASB reactor also maintained a stable anaerobic process and can thus reduce the cost of nutrients addition. We have shown that biogas production from wheat straw can be competitive by pretreatment, high methane production rate in UASB reactors and also by co-digestion with seaweed hydrolysate., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Green seaweed Ulva lactuca harvested from the North Sea near Zeeland (The Netherlands) was characterized as feedstock for acetone, ethanol and ethanol fermentation. Solubilization of over 90% of sugars was achieved by hot-water treatment followed by hydrolysis using commercial cellulases. A hydrolysate was used for the production of acetone, butanol and ethanol (ABE) by Clostridium acetobutylicum and Clostridium beijerinckii. Hydrolysate-based media were fermentable without nutrient supplementation. C. beijerinckii utilized all sugars in the hydrolysate and produced ABE at high yields (0.35 g ABE/g sugar consumed), while C. acetobutylicum produced mostly organic acids (acetic and butyric acids). These results demonstrate the great potential of U. lactuca as feedstock for fermentation. Interestingly, in control cultures of C. beijerinckii on rhamnose and glucose, 1,2 propanediol was the main fermentation product (9.7 g/L)., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Many eukaryotes are closely associated with bacteria which enable them to expand their physiological capacities. Associations between algae (photosynthetic eukaryotes) and bacteria have been described for over a hundred years. A wide range of beneficial and detrimental interactions exists between macroalgae (seaweeds) and epi- and endosymbiotic bacteria that reside either on the surface or within the algal cells. While it has been shown that these chemically mediated interactions are based on the exchange of nutrients, minerals, and secondary metabolites, the diversity and specificity of macroalgal-bacterial relationships have not been thoroughly investigated. Some of these alliances have been found to be algal or bacterial species-specific, whereas others are widespread among different symbiotic partners. Reviewing 161 macroalgal-bacterial studies from the last 55 years, a definite bacterial core community, consisting of Gammaproteobacteria, CFB group, Alphaproteobacteria, Firmicutes, and Actinobacteria species, seems to exist which is specifically (functionally) adapted to an algal host-associated lifestyle. Because seaweed-bacterial associations are appealing from evolutionary and applied perspectives, future studies should integrate the aspects of diverse biological fields., (© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)

The objectives of this study were (1) to assess the bacteriocinogenic potential of bacteria derived mainly from seaweed, but also sand and seawater, (2) to identify at least some of the bacteriocins produced, if any and (3) to determine if they are unique to the marine environment and/or novel. Fifteen Bacillus licheniformis or pumilus isolates with antimicrobial activity against at least one of the indicator bacteria used were recovered. Some, at least, of the antimicrobials produced were bacteriocins, as they were proteinaceous and the producers displayed immunity. Screening with PCR primers for known Bacillus bacteriocins revealed that three seaweed-derived Bacillus licheniformis harbored the bli04127 gene which encodes one of the peptides of the two-peptide lantibiotic lichenicidin. Production of both lichenicidin peptides was then confirmed by mass spectrometry. This is the first definitive proof of bacteriocin production by seaweed-derived bacteria. The authors acknowledge that the bacteriocin produced has previously been discovered and is not unique to the marine environment. However, the other marine isolates likely produce novel bacteriocins, as none harboured genes for known Bacillus bacteriocins.

Background: Seaweeds of the Laurencia genus have a broad geographic distribution and are largely recognized as important sources of secondary metabolites, mainly halogenated compounds exhibiting diverse potential pharmacological activities and relevant ecological role as anti-epibiosis. Host-microbe interaction is a driving force for co-evolution in the marine environment, but molecular studies of seaweed-associated microbial communities are still rare. Despite the large amount of research describing the chemical compositions of Laurencia species, the genetic knowledge regarding this genus is currently restricted to taxonomic markers and general genome features. In this work we analyze the transcriptomic profile of L. dendroidea J. Agardh, unveil the genes involved on the biosynthesis of terpenoid compounds in this seaweed and explore the interactions between this host and its associated microbiome., Results: A total of 6 transcriptomes were obtained from specimens of L. dendroidea sampled in three different coastal locations of the Rio de Janeiro state. Functional annotations revealed predominantly basic cellular metabolic pathways. Bacteria was the dominant active group in the microbiome of L. dendroidea, standing out nitrogen fixing Cyanobacteria and aerobic heterotrophic Proteobacteria. The analysis of the relative contribution of each domain highlighted bacterial features related to glycolysis, lipid and polysaccharide breakdown, and also recognition of seaweed surface and establishment of biofilm. Eukaryotic transcripts, on the other hand, were associated with photosynthesis, synthesis of carbohydrate reserves, and defense mechanisms, including the biosynthesis of terpenoids through the mevalonate-independent pathway., Conclusions: This work describes the first transcriptomic profile of the red seaweed L. dendroidea, increasing the knowledge about ESTs from the Florideophyceae algal class. Our data suggest an important role for L. dendroidea in the primary production of the holobiont and the role of Bacteria as consumers of organic matter and possibly also as nitrogen source. Furthermore, this seaweed expressed sequences related to terpene biosynthesis, including the complete mevalonate-independent pathway, which offers new possibilities for biotechnological applications using secondary metabolites from L. dendroidea.