Description of Cellulophaga baltica gen. nov., sp. nov. and Cellulophaga fucicola gen. nov., sp. nov. and reclassification of [Cytophaga] lytica to Cellulophaga lytica gen. nov., comb. nov

Bioprospecting for Novel Bacterial Sources of Hydrolytic Enzymes and Antimicrobials in the Romanian Littoral Zone of the Black Sea

Marine microorganisms have evolved a large variety of metabolites and biochemical processes, providing great opportunities for biotechnologies. In the search for new hydrolytic enzymes and antimicrobial compounds with enhanced characteristics, the current study explored the diversity of cultured and uncultured marine bacteria in Black Sea water from two locations along the Romanian coastline. Microbial cell density in the investigated samples varied between 65 and 12.7 × 10³ CFU·mL^-1. The total bacterial community identified by Illumina sequencing of 16S rRNA gene comprised 185 genera belonging to 46 classes, mainly Gammaproteobacteria, Alphaproteobacteria, Flavobacteriia, and 24 phyla. The 66 bacterial strains isolated on seawater-based culture media belonged to 33 genera and showed variable growth temperatures, growth rates, and salt tolerance. A great fraction of these strains, including Pseudoalteromonas and Flavobacterium species, produced extracellular proteases, lipases, and carbohydrases, while two strains belonging to the genera Aquimarina and Streptomyces exhibited antimicrobial activity against human pathogenic bacteria. This study led to a broader view on the diversity of microbial communities in the Black Sea, and provided new marine strains with hydrolytic and antimicrobial capabilities that may be exploited in industrial and pharmaceutical applications.

Multifunctional Enzyme with Endoglucanase and Alginase/Glucuronan Lyase Activities from Bacterium Cellulophaga lytica

Cellulophaga lytica is a Gram-negative aerobic bacterium in the genome of which there are many genes encoding polysaccharide degrading enzymes. One of the enzymes named ClGP contains a glycoside hydrolase domain from the GH5 family and a polysaccharide lyase domain from the PL31 family. The enzyme also contains the TAT signaling peptide and the TIGR04183 domain that indicates extracellular nature of the enzyme. Phylogenetic analysis has shown that the enzymes most closely related to ClGP and containing all four domains (TAT, GH5, PL31, TIGR04183) are widespread among bacterial species belonging to the Flavobacteriaceae family. ClGP produced by the recombinant strain of E. coli was purified and characterized. ClGP exhibited activity of endoglucanase (EC 3.2.1.4) and catalyzed hydrolysis of β-D-glucan, carboxymethyl cellulose sodium salt (CMC-Na), and amorphous cellulose, but failed to hydrolyze microcrystalline cellulose and xylan. Products of CMC hydrolysis were cellobiose and cellotriose, whereas β-D-glucan was hydrolyzed to glucose, cellobiose, cellotetraose, and cellopentaose. ClGP was more active against the poly-β-D-mannuronate blocks than against the poly-α-L-glucuronate blocks of alginic acid. This indicates that the enzyme is a polyM lyase (EC 4.2.2.3). ClGP was active against polyglucuronic acid, so it displayed a glucuronan lyase (EC 4.2.2.14) activity. The enzyme had a neutral pH-optimum, was stable in the pH range 6.0-8.0, and displayed moderate thermal stability. ClGP effectively saccharified two species of brown algae, Saccharina latissima and Laminaria digitata, that suggests its potential for use in the production of biofuel from macroalgae.

Long-Term Warming of Baltic Sea Coastal Waters Affects Bacterial Communities in Bottom Water and Sediments Differently

Coastal marine ecosystems are some of the most diverse natural habitats while being highly vulnerable in the face of climate change. The combination of anthropogenic influence from land and ongoing climate change will likely have severe effects on the environment, but the precise response remains uncertain. This study compared an unaffected "control" Baltic Sea bay to a "heated" bay that has undergone artificial warming from cooling water release from a nuclear power plant for ~50 years. This heated the water in a similar degree to IPCC SSP5-8.5 predictions by 2100 as natural systems to study temperature-related climate change effects. Bottom water and surface sediment bacterial communities and their biogeochemical processes were investigated to test how future coastal water warming alters microbial communities; shifts seasonal patterns, such as increased algae blooming; and influences nutrient and energy cycling, including elevated respiration rates. 16S rRNA gene amplicon sequencing and geochemical parameters demonstrated that heated bay bottom water bacterial communities were influenced by increased average temperatures across changing seasons, resulting in an overall Shannon's H diversity loss and shifts in relative abundances. In contrast, Shannon's diversity increased in the heated surface sediments. The results also suggested a trend toward smaller-sized microorganisms within the heated bay bottom waters, with a 30% increased relative abundance of small size picocyanobacteria in the summer (June). Furthermore, bacterial communities in the heated bay surface sediment displayed little seasonal variability but did show potential changes of long-term increased average temperature in the interplay with related effects on bottom waters. Finally, heated bay metabolic gene predictions from the 16S rRNA gene sequences suggested raised anaerobic processes closer to the sediment-water interface. In conclusion, climate change will likely alter microbial seasonality and diversity, leading to prolonged and increased algae blooming and elevated respiration rates within coastal waters.

Metagenomics analysis of cultured mucosal bacteria from colorectal cancer and adjacent normal mucosal tissues

Introduction. Colorectal cancer (CRC) is one of the most common cancers worldwide. Multiple risk factors are involved in CRC development, including age, genetics, lifestyle, diet and environment. Of these, the role of the gut microbiota in cancer biology is increasingly recognized.Hypothesis/Gap Statement. Micro-organisms have been widely detected in stool samples, but few mucosal samples have been detected and sequenced in depth.Aim. Analysis of cultured mucosal bacteria from colorectal cancer and adjacent normal mucosal tissues with metagenomics sequencing.Methodology. Twenty-eight paired tumour and non-tumour tissues from 14 patients undergoing surgery for CRC were analysed. We removed the influence of eukaryotic cells via culture. The composition of mucosal microbiota in intestinal mucosa were detected and analysed with metagenomic sequencing.Results. Compared with non-cultured mucosal sample, 80 % bacteria species could be detected after culture. Moreover, after culture, additional 30 % bacteria could be detected, compared with non-cultured samples. Since after culture it was difficult to estimate the original abundance of microbiome, we focused on the identification of the CRC tissue-specific species. There were 298 bacterial species, which could only be cultured and detected in CRC tissues. Myroides odoratimimus and Cellulophaga baltica could be isolated from all the tumour samples of 14 CRC patients, suggesting that these species may be related to tumour occurrence and development. Further functional analysis indicated that bacteria from CRC tissues showed more active functions, including basic metabolism, signal transduction and survival activities.Conclusion. We used a new method based on culture to implement information on prokaryotic taxa, and related functions, which samples were from colorectal tissues. This method is suitable for removing eukaryotic contamination and detecting micro-organisms from other tissues.

Optimization of Fermentation Conditions for Carrageenase Production by Cellulophaga Species: A Comparative Study

Simple Summary

Cellulophaga species are rarely studied marine bacteria with the potential for carrageenase production. We examined the carrageenase secretion ability of six bacterial species from the Cellulophaga genus. Among them, C. algicola produced the maximum amount of ι-carrageenase. Most of the bacteria produced their highest quantity of enzymes at 25 °C after 48 h of incubation time. The maximum enzyme production was achieved with the fermentation medium composition of 30 g/L sea salt, 1.4 g/L furcellaran and 3 g/L yeast extract. In addition, the properties of the ultrafiltered ι-carrageenase extracted from C. algicola were studied.

Abstract

Carrageenases appear in various species of marine bacteria and are widely used for the degradation of carrageenans, the commercially significant sulphated polysaccharides. The carrageenase production ability of six different Cellulophaga species was identified, with ι-carrageenase being the most abundant carrageenolytic enzyme. C. algicola was the most potent strain, followed by C. fucicola and C. geojensis, whereas C. pacifica was the least effective carrageenase producer among the studied strains. The enzyme production was maximized using the one-factor-at-a-time optimization method. The optimal incubation temperature was identified as 25 °C and the incubation time was set as 48 h for all tested species. The optimal medium composition for Cellulophaga strains was determined as 30 g/L sea salt, 1.4 g/L furcellaran, and 3 g/L yeast extract. An ultrafiltered enzyme extracted from C. algicola had the highest activity at around 40 °C. The optimal pH for enzymatic degradation was determined as 7.8, and the enzyme was fairly stable at temperatures up to 40 °C.

Extremophiles in Soil Communities of Former Copper Mining Sites of the East Harz Region (Germany) Reflected by Re-Analyzed 16S rRNA Data

The east and southeast rim of Harz mountains (Germany) are marked by a high density of former copper mining places dating back from the late 20th century to the middle age. A set of 18 soil samples from pre- and early industrial mining places and one sample from an industrial mine dump have been selected for investigation by 16S rRNA and compared with six samples from non-mining areas. Although most of the soil samples from the old mines show pH values around 7, RNA profiling reflects many operational taxonomical units (OTUs) belonging to acidophilic genera. For some of these OTUs, similarities were found with their abundances in the comparative samples, while others show significant differences. In addition to pH-dependent bacteria, thermophilic, psychrophilic, and halophilic types were observed. Among these OTUs, several DNA sequences are related to bacteria which are reported to show the ability to metabolize special substrates. Some OTUs absent in comparative samples from limestone substrates, among them Thaumarchaeota were present in the soil group from ancient mines with pH > 7. In contrast, acidophilic types have been found in a sample from a copper slag deposit, e.g., the polymer degrading bacterium Granulicella and Acidicaldus, which is thermophilic, too. Soil samples of the group of pre-industrial mines supplied some less abundant, interesting OTUs as the polymer-degrading Povalibacter and the halophilic Lewinella and Halobacteriovorax. A particularly high number of bacteria (OTUs) which had not been detected in other samples were found at an industrial copper mine dump, among them many halophilic and psychrophilic types. In summary, the results show that soil samples from the ancient copper mining places contain soil bacterial communities that could be a promising source in the search for microorganisms with valuable metabolic capabilities.

Anti-biofouling properties of poly(dimethyl siloxane) with RAFT photopolymerized acrylate/methacrylate surface grafts against model marine organisms

Biofouling of man-made surfaces by marine organisms is a global problem with both financial and environmental consequences. However, the development of non-toxic anti-biofouling coatings is challenged by the diversity of fouling organisms. One possible solution leverages coatings composed of diverse chemical constituents. Reversible addition-fragmentation chain-transfer (RAFT) photopolymerization was used to modify poly(dimethylsiloxane) (PDMSe) surfaces with polymeric grafts composed of three successive combinations of acrylamide, acrylic acid, and hydroxyethyl methacrylate. RAFT limited conflicting variables and allowed for the effect of graft chemistry to be isolated. While all compositions enhanced the anti-biofouling performance compared with the PDMSe control, the ternary, amphiphilic copolymer was the most effective with 98% inhibition of the attachment of zoospores of the green alga Ulva linza, 94% removal of cells of the diatom Navicula incerta, and 62% removal of cells of the bacterium Cellulophaga lytica. However, none of the graft compositions tested were able to mitigate reattachment of adult barnacles, Amphibalanus amphitrite.

Seaweed and Seaweed Bioactives for Mitigation of Enteric Methane: Challenges and Opportunities

Seaweeds contain a myriad of nutrients and bioactives including proteins, carbohydrates and to a lesser extent lipids as well as small molecules including peptides, saponins, alkaloids and pigments. The bioactive bromoform found in the red seaweed Asparagopsis taxiformis has been identified as an agent that can reduce enteric CH4 production from livestock significantly. However, sustainable supply of this seaweed is a problem and there are some concerns over its sustainable production and potential negative environmental impacts on the ozone layer and the health impacts of bromoform. This review collates information on seaweeds and seaweed bioactives and the documented impact on CH4 emissions in vitro and in vivo as well as associated environmental, economic and health impacts.

Bacterial diversity in six species of fresh edible seaweeds submitted to high pressure processing and long-term refrigerated storage

Seaweeds are highly perishable foods due to their richness in nutrients. High pressure processing (HPP) has been applied for extending the shelf life of fresh seaweeds but there is no information on the effect of HPP on the bacterial diversity of seaweeds. The culturable bacteria of six species of fresh edible seaweeds (green seaweeds Codium fragile and Ulva lactuca, brown seaweeds Himanthalia elongata, Laminaria ochroleuca and Undaria pinnatifida, and red seaweed Chondrus crispus) were investigated and compared to those of HPP-treated (400 and 600 MPa for 5 min) seaweeds, at the start and end of their refrigerated storage period. A total of 523 and 506 bacterial isolates were respectively retrieved from untreated and HPP-treated seaweeds. Isolates from untreated seaweeds belonged to 18 orders, 35 families, 71 genera and 135 species whereas isolates from HPP-treated seaweeds belonged to 13 orders, 23 families, 43 genera and 103 species. HPP treatment significantly reduced the number of isolates belonging to 6 families and greatly increased the number of Bacillaceae isolates. At the end of storage, decreases in bacterial diversity at the genus and species level were observed for untreated as well as for HPP-treated seaweeds.

Quyushengxin Formula Causes Differences in Bacterial and Phage Composition in Ulcerative Colitis Patients

Background

Ulcerative colitis (UC) is a chronic inflammatory disease that affects the colon and the rectum. Recently, some studies have shown that microorganisms in the gut play important roles in many chronic diseases such as UC.

Methods

To study the candidate viruses and bacteria involved in UC and to investigate the therapeutic mechanism of Quyushengxin formula (QYSX) in UC patients, metagenomic sequencing was performed on the feces from healthy donors and UC patients before and after QYSX treatment.

Results

QYSX improved the symptoms of UC. In all participants, Caudovirales and Herpesvirales were the most dominant viruses. The abundance of Caudovirales in UC patients was significantly higher than that in the normal controls, while QYSX restored Caudovirales abundance. Furthermore, the abundance of crAssphage was enhanced in UC patients compared with the normal control, while the diversity was then decreased after QYSX treatment. However, there was no significant difference (P > 0.05). Additionally, other non-crAssphage bacteriophages including phiST, SP-10, and phi17:2 were higher in UC patients and QYSX decreased these viruses, while the trends of MED4−213, P-HM1, and P−HM2 were adverse. Interestingly, PhiDP23.1 was only found in UC patients before and after QYSX treatment. In addition, Bifidobacterium, Bacteroidetes, Prevotellaceae, Actinobacteria, and Corynebacteriales were the biomarkers in UC patients after QYSX treatment due to their high abundance. GO terms and KEGG analysis showed that the identified gut microbiome was involved in many biological processes and pathways.

Conclusions

QYSX could regulate disordered gut microbiome and phages, indicating that QYSX has great therapeutic potential for UC.

Analysis of 1,000 Type-Strain Genomes Improves Taxonomic Classification of Bacteroidetes

Although considerable progress has been made in recent years regarding the classification of bacteria assigned to the phylum Bacteroidetes, there remains a need to further clarify taxonomic relationships within a diverse assemblage that includes organisms of clinical, piscicultural, and ecological importance. Bacteroidetes classification has proved to be difficult, not least when taxonomic decisions rested heavily on interpretation of poorly resolved 16S rRNA gene trees and a limited number of phenotypic features. Here, draft genome sequences of a greatly enlarged collection of genomes of more than 1,000 Bacteroidetes and outgroup type strains were used to infer phylogenetic trees from genome-scale data using the principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families and genera, including taxa proposed long ago such as Bacteroides, Cytophaga, and Flavobacterium but also quite recent taxa, as well as a few species were shown to be in need of revision. According proposals are made for the recognition of new orders, families and genera, as well as the transfer of a variety of species to other genera. In addition, emended descriptions are given for many species mainly involving information on DNA G+C content and (approximate) genome size, both of which can be considered valuable taxonomic markers. We detected many incongruities when comparing the results of the present study with existing classifications, which appear to be caused by insufficiently resolved 16S rRNA gene trees or incomplete taxon sampling. The few significant incongruities found between 16S rRNA gene and whole genome trees underline the pitfalls inherent in phylogenies based upon single gene sequences and the impediment in using ordinary bootstrapping in phylogenomic studies, particularly when combined with too narrow gene selections. While a significant degree of phylogenetic conservation was detected in all phenotypic characters investigated, the overall fit to the tree varied considerably, which is one of the probable causes of misclassifications in the past, much like the use of plesiomorphic character states as diagnostic features.

The role of salinity on the changes of the biomass characteristics and on the performance of an OMBR treating tannery wastewater

Tannery wastewaters are difficult to treat biologically due to the high salinity and organic matter concentration. Conventional treatments, like sequential batch reactors (SBR) and membrane bioreactors (MBR), have showed settling problems, in the case of SBR, and ultrafiltration (UF) membrane fouling in the case of MBR, slowing their industrial application. In this work, the treatment of tannery wastewater with an osmotic membrane bioreactor (OMBR) is assessed. Forward osmosis (FO) membranes are characterized by a much lower fouling degree than UF membranes. The permeate passes through the membrane pores (practically only water by the high membrane rejection) from the feed solution to the draw solution, which is also an industrial wastewater (ammonia absorption effluent) in this work. Experiments were carried out at laboratory scale with a FO CTA-NW membrane from Hydration Technology Innovations (HTI). Tannery wastewater was treated by means of an OMBR using as DS an actual industrial wastewater mainly consisting of ammonium sulphate. The monitoring of the biological process was carried out with biological indicators like microbial hydrolytic enzymatic activities, dissolved and total adenosine triphosphate (ATP) in the mixed liquor and microbial population. Results indicated a limiting conductivity in the reactor of 35 mS cm-1 (on the 43th operation day), from which process was deteriorated. This process performance diminution was associated by a high decrease of the dehydrogenase activity and a sudden increase of the protease and lipase activities. The increase of the bacterial stress index also described appropriately the process performance. Regarding the relative abundance of bacterial phylotypes, 37 phyla were identified in the biomass. Proteobacteria were the most abundant (varying the relative abundance between 50.29% and 34.78%) during the first 34 days of operation. From this day on, Bacteroidetes were detected in a greater extent varying the relative abundance of this phylum between 27.20% and 40.45%.

Multiple mechanisms drive phage infection efficiency in nearly identical hosts

Phage-host interactions are critical to ecology, evolution, and biotechnology. Central to those is infection efficiency, which remains poorly understood, particularly in nature. Here we apply genome-wide transcriptomics and proteomics to investigate infection efficiency in nature's own experiment: two nearly identical (genetically and physiologically) Bacteroidetes bacterial strains (host18 and host38) that are genetically intractable, but environmentally important, where phage infection efficiency varies. On host18, specialist phage phi18:3 infects efficiently, whereas generalist phi38:1 infects inefficiently. On host38, only phi38:1 infects, and efficiently. Overall, phi18:3 globally repressed host18's transcriptome and proteome, expressed genes that likely evaded host restriction/modification (R/M) defenses and controlled its metabolism, and synchronized phage transcription with translation. In contrast, phi38:1 failed to repress host18's transcriptome and proteome, did not evade host R/M defenses or express genes for metabolism control, did not synchronize transcripts with proteins and its protein abundances were likely targeted by host proteases. However, on host38, phi38:1 globally repressed host transcriptome and proteome, synchronized phage transcription with translation, and infected host38 efficiently. Together these findings reveal multiple infection inefficiencies. While this contrasts the single mechanisms often revealed in laboratory mutant studies, it likely better reflects the phage-host interaction dynamics that occur in nature.

Draft Genome Sequence of Newly Isolated Agarolytic Bacteria Cellulophaga omnivescoria sp. nov. W5C Carrying Several Gene Loci for Marine Polysaccharide Degradation

The continued research in the isolation of novel bacterial strains is inspired by the fact that native microorganisms possess certain desired phenotypes necessary for recombinant microorganisms in the biotech industry. Most studies have focused on the isolation and characterization of strains from marine ecosystems as they present a higher microbial diversity than other sources. In this study, a marine bacterium, W5C, was isolated from red seaweed collected from Yeosu, South Korea. The isolate can utilize several natural polysaccharides such as agar, alginate, carrageenan, and chitin. Genome sequence and comparative genomics analyses suggest that strain W5C belongs to a novel species of the Cellulophaga genus, from which the name Cellulophaga omnivescoria sp. nov. is proposed. Its genome harbors 3,083 coding sequences and 146 carbohydrate-active enzymes (CAZymes). Compared to other reported Cellulophaga species, the genome of W5C contained a higher proportion of CAZymes (4.7%). Polysaccharide utilization loci (PUL) for agar, alginate, and carrageenan were identified in the genome, along with other several putative PULs. These PULs are excellent sources for discovering novel hydrolytic enzymes and pathways with unique characteristics required for biorefinery applications, particularly in the utilization of marine renewable biomass. The type strain is JCM 32108^T (= KCTC 13157BP^T).

Complete genome sequence and analysis of three kinds of β-agarase of Cellulophaga lytica DAU203 isolated from marine sediment

Cellulophaga lytica DAU203 (KACC 19187), isolated from the marine sediment in Korea, has a strong ability to degrade agar. The genome of C. lytica DAU203 contains a single chromosome that is 3,952,957bp in length, with 32.02% G+C contents. The genomic information predicted that the DAU203 has the potential to be utilized in various enzymatic industries.

Genome-Based Taxonomic Classification of Bacteroidetes

The bacterial phylum Bacteroidetes, characterized by a distinct gliding motility, occurs in a broad variety of ecosystems, habitats, life styles, and physiologies. Accordingly, taxonomic classification of the phylum, based on a limited number of features, proved difficult and controversial in the past, for example, when decisions were based on unresolved phylogenetic trees of the 16S rRNA gene sequence. Here we use a large collection of type-strain genomes from Bacteroidetes and closely related phyla for assessing their taxonomy based on the principles of phylogenetic classification and trees inferred from genome-scale data. No significant conflict between 16S rRNA gene and whole-genome phylogenetic analysis is found, whereas many but not all of the involved taxa are supported as monophyletic groups, particularly in the genome-scale trees. Phenotypic and phylogenomic features support the separation of Balneolaceae as new phylum Balneolaeota from Rhodothermaeota and of Saprospiraceae as new class Saprospiria from Chitinophagia. Epilithonimonas is nested within the older genus Chryseobacterium and without significant phenotypic differences; thus merging the two genera is proposed. Similarly, Vitellibacter is proposed to be included in Aequorivita. Flexibacter is confirmed as being heterogeneous and dissected, yielding six distinct genera. Hallella seregens is a later heterotypic synonym of Prevotella dentalis. Compared to values directly calculated from genome sequences, the G+C content mentioned in many species descriptions is too imprecise; moreover, corrected G+C content values have a significantly better fit to the phylogeny. Corresponding emendations of species descriptions are provided where necessary. Whereas most observed conflict with the current classification of Bacteroidetes is already visible in 16S rRNA gene trees, as expected whole-genome phylogenies are much better resolved.

Antimicrobial Activities of Bacteria Associated with the Brown Alga Padina pavonica

Macroalgae belonging to the genus Padina are known to produce antibacterial compounds that may inhibit growth of human- and animal pathogens. Hitherto, it was unclear whether this antibacterial activity is produced by the macroalga itself or by secondary metabolite producing epiphytic bacteria. Here we report antibacterial activities of epiphytic bacteria isolated from Padina pavonica (Peacocks tail) located on northern coast of Tunisia. Eighteen isolates were obtained in pure culture and tested for antimicrobial activities. Based on the 16S rRNA gene sequences the isolates were closely related to Proteobacteria (12 isolates; 2 Alpha- and 10 Gammaproteobacteria), Firmicutes (4 isolates) and Actinobacteria (2 isolates). The antimicrobial activity was assessed as inhibition of growth of 12 species of pathogenic bacteria (Aeromonas salmonicida, A. hydrophila, Enterobacter xiangfangensis, Enterococcus faecium, Escherichia coli, Micrococcus sp., Salmonella typhimurium, Staphylococcus aureus, Streptococcus sp., Vibrio alginoliticus, V. proteolyticus, V. vulnificus) and one pathogenic yeast (Candida albicans). Among the Firmicutes, isolate P8, which is closely related to Bacillus pumilus, displayed the largest spectrum of growth inhibition of the pathogenic bacteria tested. The results emphasize the potential use of P. pavonica associated antagonistic bacteria as producers of novel antibacterial compounds.

Discovering novel enzymes by functional screening of plurigenomic libraries from alga-associated Flavobacteriia and Gammaproteobacteria

Alga-associated microorganisms, in the context of their numerous interactions with the host and the complexity of the marine environment, are known to produce diverse hydrolytic enzymes with original biochemistry. We recently isolated several macroalgal-polysaccharide-degrading bacteria from the surface of the brown alga Ascophyllum nodosum. These active isolates belong to two classes: the Flavobacteriia and the Gammaproteobacteria. In the present study, we constructed two "plurigenomic" (with multiple bacterial genomes) libraries with the 5 most interesting isolates (regarding their phylogeny and their enzymatic activities) of each class (Fv and Gm libraries). Both libraries were screened for diverse hydrolytic activities. Five activities, out of the 48 previously identified in the natural polysaccharolytic isolates, were recovered by functional screening: a xylanase (GmXyl7), a beta-glucosidase (GmBg1), an esterase (GmEst7) and two iota-carrageenases (Fvi2.5 and Gmi1.3). We discuss here the potential role of the used host-cell, the average DNA insert-sizes and the used restriction enzymes on the divergent screening yields obtained for both libraries and get deeper inside the "great screen anomaly". Interestingly, the discovered esterase probably stands for a novel family of homoserine o-acetyltransferase-like-esterases, while the two iota-carrageenases represent new members of the poorly known GH82 family (containing only 19 proteins since its description in 2000). These original results demonstrate the efficiency of our uncommon "plurigenomic" library approach and the underexplored potential of alga-associated cultivable microbiota for the identification of novel and algal-specific enzymes.

Antibacterial activity of aquatic gliding bacteria

The study aimed to screen and isolate strains of freshwater aquatic gliding bacteria, and to investigate their antibacterial activity against seven common pathogenic bacteria. Submerged specimens were collected and isolated for aquatic gliding bacteria using four different isolation media (DW, MA, SAP2, and Vy/2). Gliding bacteria identification was performed by 16S rRNA gene sequencing and phylogenetic analysis. Crude extracts were obtained by methanol extraction. Antibacterial activity against seven pathogenic bacteria was examined by agar-well diffusion assay. Five strains of aquatic gliding bacteria including RPD001, RPD008, RPD018, RPD027 and RPD049 were isolated. Each submerged biofilm and plastic specimen provided two isolates of gliding bacteria, whereas plant debris gave only one isolate. Two strains of gliding bacteria were obtained from each DW and Vy/2 isolation medium, while one strain was obtained from the SAP2 medium. Gliding bacteria strains RPD001, RPD008 and RPD018 were identified as Flavobacterium anhuiense with 96, 82 and 96 % similarity, respectively. Strains RPD049 and RPD027 were identified as F. johnsoniae and Lysobacter brunescens, respectively, with similarity equal to 96 %. Only crude extract obtained from RPD001 inhibited growth of Listeria monocytogenes (MIC 150 µg/ml), Staphylococcus aureus (MIC 75 µg/ml) and Vibrio cholerae (MIC 300 µg/ml), but showed weak inhibitory effect on Salmonella typhimurium (MIC > 300 µg/ml). Gliding bacterium strain RPD008 should be considered to a novel genus separate from Flavobacterium due to its low similarity value. Crude extract produced by RPD001 showed potential for development as a broad antibiotic agent.

A unique self-organization of bacterial sub-communities creates iridescence in Cellulophaga lytica colony biofilms

Iridescent color appearances are widespread in nature. They arise from the interaction of light with micron- and submicron-sized physical structures spatially arranged with periodic geometry and are usually associated with bright angle-dependent hues. Iridescence has been reported for many animals and marine organisms. However, iridescence has not been well studied in bacteria. Recently, we reported a brilliant "pointillistic" iridescence in colony biofilms of marine Flavobacteria that exhibit gliding motility. The mechanism of their iridescence is unknown. Here, using a multi-disciplinary approach, we show that the cause of iridescence is a unique periodicity of the cell population in the colony biofilm. Cells are arranged together to form hexagonal photonic crystals. Our model highlights a novel pattern of self-organization in a bacterial biofilm. "Pointillistic" bacterial iridescence can be considered a new light-dependent phenomenon for the field of microbiology.

The Cultivable Surface Microbiota of the Brown Alga Ascophyllum nodosum is Enriched in Macroalgal-Polysaccharide-Degrading Bacteria

Bacteria degrading algal polysaccharides are key players in the global carbon cycle and in algal biomass recycling. Yet the water column, which has been studied largely by metagenomic approaches, is poor in such bacteria and their algal-polysaccharide-degrading enzymes. Even more surprisingly, the few published studies on seaweed-associated microbiomes have revealed low abundances of such bacteria and their specific enzymes. However, as macroalgal cell-wall polysaccharides do not accumulate in nature, these bacteria and their unique polysaccharidases must not be that uncommon. We, therefore, looked at the polysaccharide-degrading activity of the cultivable bacterial subpopulation associated with Ascophyllum nodosum. From A. nodosum triplicates, 324 bacteria were isolated and taxonomically identified. Out of these isolates, 78 (~25%) were found to act on at least one tested algal polysaccharide (agar, ι- or κ-carrageenan, or alginate). The isolates “active” on algal-polysaccharides belong to 11 genera: Cellulophaga, Maribacter, Algibacter, and Zobellia in the class Flavobacteriia (41) and Pseudoalteromonas, Vibrio, Cobetia, Shewanella, Colwellia, Marinomonas, and Paraglaceciola in the class Gammaproteobacteria (37). A major part represents likely novel species. Different proportions of bacterial phyla and classes were observed between the isolated cultivable subpopulation and the total microbial community previously identified on other brown algae. Here, Bacteroidetes and Gammaproteobacteria were found to be the most abundant and some phyla (as Planctomycetes and Cyanobacteria) frequently encountered on brown algae weren't identified. At a lower taxonomic level, twelve genera, well-known to be associated with algae (with the exception for Colwellia), were consistently found on all three A. nosodum samples. Even more interesting, 9 of the 11 above mentioned genera containing polysaccharolytic isolates were predominant in this common core. The cultivable fraction of the bacterial community associated with A. nodosum is, thus, significantly enriched in macroalgal-polysaccharide-degrading bacteria and these bacteria seem important for the seaweed holobiont even though they are under-represented in alga-associated microbiome studies.

Draft Genome Sequence of Cellulophaga sp. E6, a Marine Algal Epibiont That Produces a Quorum-Sensing Inhibitory Compound Active against Pseudomonas aeruginosa

The genus Cellulophaga is composed of obligate aerobic Gram-negative bacteria commonly found in association with marine algae. We report the approximately 4.42-Mbp draft genome sequence of Cellulophaga sp. E6, which inhibits N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C₁₂-HSL)–mediated quorum sensing (QS), lasB transcription, and biofilm formation by Pseudomonas aeruginosa.

Emerging flavobacterial infections in fish: A review

Flavobacterial diseases in fish are caused by multiple bacterial species within the family Flavobacteriaceae and are responsible for devastating losses in wild and farmed fish stocks around the world. In addition to directly imposing negative economic and ecological effects, flavobacterial disease outbreaks are also notoriously difficult to prevent and control despite nearly 100 years of scientific research. The emergence of recent reports linking previously uncharacterized flavobacteria to systemic infections and mortality events in fish stocks of Europe, South America, Asia, Africa, and North America is also of major concern and has highlighted some of the difficulties surrounding the diagnosis and chemotherapeutic treatment of flavobacterial fish diseases. Herein, we provide a review of the literature that focuses on Flavobacterium and Chryseobacterium spp. and emphasizes those associated with fish.

Isolation and distribution of iridescent Cellulophaga and other iridescent marine bacteria from the Charente-Maritime coast, French Atlantic

An intense colored marine bacterium, identified as Cellulophaga lytica, was isolated previously from a sea anemone surface on the Charente-Maritime rocky shore (Atlantic Coast, France), and iridescence of its colonies under direct light was recently described. In addition, iridescence intensities were found to differ strongly between C. lytica strains from different culture collections. However, importantly, the occurrence and distribution of iridescent bacteria in the marine environment were still unknown. Therefore, in this study, a search was undertaken for marine iridescent bacterial strains in different biotopes of the Charente-Maritime coast. Various marine samples (water, sediment, macroalgae, other macroorganisms and detritus) were collected from seven biotopes using a direct plate inoculation method. As a result, 34 iridescent strains related to the genus Cellulophaga, as well as 63 iridescent strains affiliated to the genera Tenacibaculum and Aquimarina, were isolated. Iridescent colors were different according to the genera but iridescent marine bacteria were widely distributed. However, a majority of strains were isolated from rocky shores and, in particular, red seaweed surfaces and mollusks. The data from the study suggested that isolates with iridescent properties were well conserved in stressful environments such as the coastal shoreline. This origin may provide an insight into the ecological and biological functions of iridescence.

Sinomicrobium oceani gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from marine sediment

A marine bacterium, designated SCSIO 03483T, was isolated from a marine sediment sample collected from the Nansha Islands in the South China Sea. The strain produced roundish colonies with diffusible yellow-coloured pigment on nutrient agar medium or marine agar 2216. Optimal growth occurred in the presence of 0–4 % (w/v) NaCl, at pH 7.0 and a temperature range of 28–37 °C. 16S rRNA gene sequence analysis indicated that the isolate belonged to the family Flavobacteriaceae and showed relatively high sequence similarity with Imtechella halotolerans K1T (92.7 %). Phylogenetic analysis based on nearly complete 16S rRNA gene sequences revealed that the isolate shared a lineage with members of the genera Imtechella , Joostella and Zhouia . Phospholipids were phosphatidylethanolamine, two unidentified aminolipids and three unknown polar lipids. The major respiratory quinone was MK-6 and the major fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω6c/C16 : 1ω7c). The DNA G+C content of strain SCSIO 03483T was 38.4 mol%. On the basis of phenotypic, chemotaxonomic and molecular data, strain SCSIO 03483T represents a novel species in a new genus in the family Flavobacteriaceae , for which the name Sinomicrobium oceani gen. nov., sp. nov. is proposed. The type strain of Sinobacterium oceani is SCSIO 03483T ( = KCTC 23994T = CGMCC 1.12145T).

How deep-sea wood falls sustain chemosynthetic life

Large organic food falls to the deep sea – such as whale carcasses and wood logs – are known to serve as stepping stones for the dispersal of highly adapted chemosynthetic organisms inhabiting hot vents and cold seeps. Here we investigated the biogeochemical and microbiological processes leading to the development of sulfidic niches by deploying wood colonization experiments at a depth of 1690 m in the Eastern Mediterranean for one year. Wood-boring bivalves of the genus Xylophaga played a key role in the degradation of the wood logs, facilitating the development of anoxic zones and anaerobic microbial processes such as sulfate reduction. Fauna and bacteria associated with the wood included types reported from other deep-sea habitats including chemosynthetic ecosystems, confirming the potential role of large organic food falls as biodiversity hot spots and stepping stones for vent and seep communities. Specific bacterial communities developed on and around the wood falls within one year and were distinct from freshly submerged wood and background sediments. These included sulfate-reducing and cellulolytic bacterial taxa, which are likely to play an important role in the utilization of wood by chemosynthetic life and other deep-sea animals.

Glitter-like iridescence within the bacteroidetes especially Cellulophaga spp.: optical properties and correlation with gliding motility

Iridescence results from structures that generate color. Iridescence of bacterial colonies has recently been described and illustrated. The glitter-like iridescence class, created especially for a few strains of Cellulophaga lytica, exhibits an intense iridescence under direct illumination. Such color appearance effects were previously associated with other bacteria from the Bacteroidetes phylum, but without clear elucidation and illustration. To this end, we compared various bacterial strains to which the iridescent trait was attributed. All Cellulophaga species and additional Bacteroidetes strains from marine and terrestrial environments were investigated. A selection of bacteria, mostly marine in origin, were found to be iridescent. Although a common pattern of reflected wavelengths was recorded for the species investigated, optical spectroscopy and physical measurements revealed a range of different glitter-like iridescence intensity and color profiles. Importantly, gliding motility was found to be a common feature of all iridescent colonies. Dynamic analyses of “glitter” formation at the edges of C. lytica colonies showed that iridescence was correlated with layer superposition. Both gliding motility, and unknown cell-to-cell communication processes, may be required for the establishment, in time and space, of the necessary periodic structures responsible for the iridescent appearance of Bacteroidetes.

What we can learn from sushi: a review on seaweed-bacterial associations

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.

Cellulophaga geojensis sp. nov., a member of the family Flavobacteriaceae isolated from marine sand

A Gram-stain-negative, aerobic, non-flagellated, non-spore-forming, motile (by gliding) bacterial strain, designated M-M6T, was isolated from marine sand of Geoje island, Korea. Strain M-M6T grew optimally at 25 °C, at pH 7.0–8.0 and in the presence of 2 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain M-M6T fell within the clade comprising Cellulophaga species, forming a coherent cluster with Cellulophaga lytica ATCC 23178T and Cellulophaga fucicola NN015860T, with which it shared 16S rRNA gene sequence similarities of 98.1 and 98.2 %, respectively. Sequence similarities between strain M-M6T and the type strains of other recognized Cellulophaga species were in the range 92.4–93.8 %. Strain M-M6T contained MK-6 as the predominant menaquinone and iso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH, and C16 : 1ω7c and/or iso-C15 : 0 2-OH as the major fatty acids. The major polar lipids detected in strain M-M6T and the type strains of C. lytica and C. fucicola were two unidentified lipids, one unidentified aminolipid and one unidentified aminophospholipid. The DNA G+C content of strain M-M6T was 35.4 mol%. Levels of DNA–DNA relatedness between strain M-M6T and C. lytica JCM 8516T and C. fucicola JCM 21778T were 33 and 35 %, respectively. Differential phenotypic properties and phylogenetic and genetic distinctiveness distinguished strain M-M6T from all recognized Cellulophaga species. On the basis of the data presented, strain M-M6T is considered to represent a novel species of the genus Cellulophaga , for which the name Cellulophaga geojensis sp. nov. is proposed. The type strain is M-M6T ( = KCTC 23498T = CCUG 60801T).

Iridescence of a marine bacterium and classification of prokaryotic structural colors

Iridescence is a property of structural color that is occasionally encountered in higher eukaryotes but that has been poorly documented in the prokaryotic kingdom. In the present work, we describe a marine bacterium, identified as Cellulophaga lytica, isolated from the surface of an anemone, that exhibits bright green iridescent colonies under direct epi-illumination. This phenomenon has not previously been investigated in detail. In this study, color changes of C. lytica colonies were observed at various angles of direct illumination or observation. Its iridescent green appearance was dominant on various growth media. Red and violet colors were also discerned on colony edges. Remarkable C. lytica bacterial iridescence was revealed and characterized using high-resolution optical spectrometry. In addition to this, by culturing other bacterial strains to which various forms of faintly iridescent traits have previously been attributed, we identify four principal appearance characteristics of structural color in prokaryotes. A new general classification of bacterial iridescence is therefore proposed in this study. Furthermore, a specific separate class is described for iridescent C. lytica strains because they exhibit what is so far a unique intense glitter-like iridescence in reflection. C. lytica is the first prokaryote discovered to produce the same sort of intense iridescence under direct illumination as that associated with higher eukaryotes, like some insects and birds. Due to the nature of bacterial biology, cultivation, and ubiquity, this discovery may be of significant interest for both ecological and nanoscience endeavors.

Complete genome sequence of Cellulophaga lytica type strain (LIM-21)

Cellulophaga lytica (Lewin 1969) Johansen et al. 1999 is the type species of the genus Cellulophaga, which belongs to the family Flavobacteriaceae within the phylum 'Bacteroidetes' and was isolated from marine beach mud in Limon, Costa Rica. The species is of biotechnological interest because its members produce a wide range of extracellular enzymes capable of degrading proteins and polysaccharides. After the genome sequence of Cellulophaga algicola this is the second completed genome sequence of a member of the genus Cellulophaga. The 3,765,936 bp long genome with its 3,303 protein-coding and 55 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

Draft genome sequence of the novel agar-digesting marine bacterium HQM9

Strain HQM9, an aerobic, rod-shaped marine bacterium from red algae, can produce agarases and liquefy solid plating media efficiently when agar is used as a coagulant. Here we report the draft genome sequence and the initial findings from a preliminary analysis of strain HQM9, which should be a novel species of Flavobacteriaceae.

Complete genome sequence of Cellulophaga algicola type strain (IC166)

Cellulophaga algicola Bowman 2000 belongs to the family Flavobacteriaceae within the phylum 'Bacteroidetes' and was isolated from Melosira collected from the Eastern Antarctic coastal zone. The species is of interest because its members produce a wide range of extracellular enzymes capable of degrading proteins and polysaccharides with temperature optima of 20-30°C. This is the first completed genome sequence of a member of the genus Cellulophaga. The 4,888,353 bp long genome with its 4,285 protein-coding and 62 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

Identification of carbohydrate metabolism genes in the metagenome of a marine biofilm community shown to be dominated by gammaproteobacteria and bacteroidetes

Polysaccharides are an important source of organic carbon in the marine environment, degradation of the insoluble, globally abundant cellulose is a major component of the marine carbon cycle. Although a number of species of cultured bacteria are known to degrade crystalline cellulose, little is known of the polysaccharide hydrolases expressed by cellulose-degrading microbial communities, particularly in the marine environment. Next generation 454 Pyrosequencing was applied to analyze the microbial community that colonizes, degrades insoluble polysaccharides in situ in the Irish Sea. The bioinformatics tool MG-RAST was used to examine the randomly sampled data for taxonomic markers, functional genes,, showed that the community was dominated by members of the Gammaproteobacteria, Bacteroidetes. Furthermore, the identification of 211 gene sequences matched to a custom-made database comprising the members of nine glycoside hydrolase families revealed an extensive repertoire of functional genes predicted to be involved in cellulose utilization. This demonstrates that the use of an in situ cellulose baiting method yielded a marine microbial metagenome considerably enriched in functional genes involved in polysaccharide degradation. The research reported here is the first designed to specifically address the bacterial communities that colonize, degrade cellulose in the marine environment, to evaluate the glycoside hydrolase (cellulase, chitinase) gene repertoire of that community, in the absence of the biases associated with PCR-based molecular techniques.

Application of molecular techniques to elucidate the influence of cellulosic waste on the bacterial community structure at a simulated low-level-radioactive-waste site

Low-level-radioactive-waste (low-level-waste) sites, including those at various U.S. Department of Energy sites, frequently contain cellulosic waste in the form of paper towels, cardboard boxes, or wood contaminated with heavy metals and radionuclides such as chromium and uranium. To understand how the soil microbial community is influenced by the presence of cellulosic waste products, multiple soil samples were obtained from a nonradioactive model low-level-waste test pit at the Idaho National Laboratory. Samples were analyzed using 16S rRNA gene clone libraries and 16S rRNA gene microarray (PhyloChip) analyses. Both methods revealed changes in the bacterial community structure with depth. In all samples, the PhyloChip detected significantly more operational taxonomic units, and therefore relative diversity, than the clone libraries. Diversity indices suggest that diversity is lowest in the fill and fill-waste interface (FW) layers and greater in the wood waste and waste-clay interface layers. Principal-coordinate analysis and lineage-specific analysis determined that the Bacteroidetes and Actinobacteria phyla account for most of the significant differences observed between the layers. The decreased diversity in the FW layer and increased members of families containing known cellulose-degrading microorganisms suggest that the FW layer is an enrichment environment for these organisms. These results suggest that the presence of the cellulosic material significantly influences the bacterial community structure in a stratified soil system.

Ekhidna lutea gen. nov., sp. nov., a member of the phylum Bacteroidetes isolated from the South East Pacific Ocean

A novel aerobic, heterotrophic bacterium, designated BiosLi39(T), was isolated from the South East Pacific Ocean. Cells were Gram-negative gliding rods forming yellow colonies on marine agar. The isolate was oxidase-, catalase- and alkaline phosphatase-positive and β-galactosidase-negative. Strain BiosLi39(T) grew at 20-37°C (optimum 30°C), at pH7.0-9.0 (optimum pH8.0) and with 20-60 g NaCl l(-1) (optimum 30-50 g NaCl l(-1)). The fatty acids (>1 %) comprised iso-C(14 : 0), iso-C(15 : 1) G, iso-C(15 : 0), anteiso-C(15 : 0), C(15 : 1) G, C(15 : 0), iso-C(15 : 0) 2-OH, iso-C(16 : 1) G, iso-C(16 : 0), iso-C(16 : 0) 3-OH, iso-C(16 : 0) 2-OH, iso-C(17 : 0) 3-OH, C(17 : 0) 2-OH and three unidentified components with equivalent chain lengths of 17.87, 18.10 and 18.71. A significant proportion of the hydroxylated fatty acids are amide-linked. The lipid pattern indicated the presence of phosphatidylethanolamine, two unidentified aminolipids and three unidentified polar lipids. The strain contained menaquinone 7 as the sole respiratory lipoquinone and did not produce flexirubin-type pigments. The G+C content of the genomic DNA was 37.2 mol%. Comparative 16S rRNA gene sequence analysis indicated that strain BiosLi39(T) was distantly related to all of the representatives of the phylum Bacteroidetes. Its closest relative was Marinoscillum furvescens IFO 15994(T), with which it shared 92.5 % 16S rRNA gene sequence similarity. On the basis of genotypic, phenotypic and chemotaxonomic characteristics, we propose a novel genus and species, Ekhidna gen. nov., sp. nov., with type strain BiosLi39(T) (=DSM 19307(T) =CIP 109600(T) =OOB 398(T)).

The uronic acids assay: a method for the determination of chemical activity on biofilm EPS

In this work, the uronic acids assay was evaluated for its potential to function as a bioassay to screen for antagonistic activity against the production of microbial biofilm exopolysaccharide (EPS). The assay was first applied to biofilms produced in the presence of two universal disinfectants (sodium hypochlorite and sodium dodecyl sulfate) known to inhibit microbial growth and biofilm formation. The performance of the assay was then characterized through statistical assessment of threshold concentrations for disinfection efficiency and consistency relative to values reported in the literature. The assay was then evaluated for its utility in screening for enzymatic or chemical inhibitors of biofilm formation (eg glycosidases, halogenated furanones, and semi-crude fractions extracted from minimally fouled marine plants) and its ability to distinguish between true anti-biofilm activity and simple disinfection. Activity was characterized as (i) no effect, (ii) a true positive effect (ie increased biofilm EPS), (iii) anti-bacterial activity (ie decreased biofilm EPS and analogous decrease in planktonic growth), and (iv) anti-biofilm EPS activity (ie decreased biofilm EPS, without analogous decrease in planktonic growth). Results demonstrate that the uronic acids assay can augment existing biofilm characterization methods by providing a quantitative measure of biofilm EPS.

Cellulophaga tyrosinoxydans sp. nov., a tyrosinase-producing bacterium isolated from seawater

An aerobic, gliding, yellow-pigmented bacterium lacking flagella and showing strong tyrosinase activity, designated strain EM41(T), was isolated from seawater on the eastern coast of Jeju Island in Korea. Growth was observed at 15-35 degrees C (optimum, 25-30 degrees C) and at pH 6.5-9.0 (optimum, pH 7.0-8.5). Cells were Gram-negative, negative for flexirubin pigments and catalase- and oxidase-positive. The G+C content of the genomic DNA was 33.5 mol% and the major respiratory quinone was menaquinone-6 (MK-6). Comparative 16S rRNA gene sequence analysis showed that strain EM41(T) formed a distinct phyletic line within the genus Cellulophaga with a 100 % bootstrap value and was most closely related to Cellulophaga pacifica KMM 3664(T) (97.0 % sequence similarity). The level of DNA-DNA relatedness between strain EM41(T) and C. pacifica KMM 3664(T) was about 17.8 %. On the basis of phenotypic and genotypic data, strain EM41(T) is considered to represent a novel species of the genus Cellulophaga, for which the name Cellulophaga tyrosinoxydans sp. nov. is proposed. The type strain is EM41(T) (=KCTC 22297(T)=DSM 21164(T)).

Bacteriophages drive strain diversification in a marine Flavobacterium: implications for phage resistance and physiological properties

Genetic, structural and physiological differences between strains of the marine bacterium Cellulophaga baltica MM#3 (Flavobacteriaceae) developing in response to the activity of two virulent bacteriophages, Phi S(M) and Phi S(T), was investigated during 3 weeks incubation in chemostat cultures. A distinct strain succession towards increased phage resistance and a diversification of the metabolic properties was observed. During the incubation the bacterial population diversified from a single strain, which was sensitive to 24 tested Cellulophaga phages, into a multistrain and multiresistant population, where the dominant strains had lost susceptibility to up to 22 of the tested phages. By the end of the experiment the cultures reached a quasi steady state dominated by Phi S(T)-resistant and Phi S(M) + Phi S(T)-resistant strains coexisting with small populations of phage-sensitive strains sustaining both phages at densities of > 10(6) plaque forming units (pfu) ml(-1). Loss of susceptibility to phage infection was associated with a reduction in the strains' ability to metabolize various carbon sources as demonstrated by BIOLOG assays. This suggested a cost of resistance in terms of reduced physiological capacity. However, there was no direct correlation between the degree of resistance and the loss of metabolic properties, suggesting either the occurrence of compensatory mutations in successful strains or that the cost of resistance in some strains was associated with properties not resolved by the BIOLOG assay. The study represents the first direct demonstration of phage-driven generation of functional diversity within a marine bacterial host population with significant implications for both phage susceptibility and physiological properties. We propose, therefore, that phage-mediated selection for resistant strains contributes significantly to the extensive microdiversity observed within specific bacterial species in marine environments.