Novel anaerobic selenium oxyanion reducers native to FGD wastewater for enhanced selenium removal

Biological treatment is a recognized approach for removing selenate and selenite oxyanions present in flue gas desulfurization (FGD) wastewater. However, the knowledge of the specific microbial species or communities responsible for reducing water-soluble selenium oxyanions to insoluble elemental selenium remains limited. In addition, the selenium oxyanion reduction genes and pathways have yet to be understood in these wastewaters. This study characterizes selenium oxyanion-reducing bacteria (SeRB) native to FGD wastewater, and the resulting elemental selenium particles formed. By selecting native SeRB microbes in a defined media, a novel resolution of these organisms has been achieved. This research identifies previously unrecognized selenium oxyanion-reducing capabilities in Anaerosolibacter, alongside predominant SeRB from Mesobacillus and Tepidibacillus genera. This work encompasses both 16S and metagenomic techniques to recover novel metagenome-assembled genomes, distinct to this environment. The biogenic selenium produced by these organisms was predominantly of elemental selenium, either amorphous or with a hexagonal structure. This study identifies the SeRB present in FGD wastewater and characterizes their selenium products, offering crucial insights to enhance the efficiency of biological treatment strategies and the potential of selenium recovery from this industrial waste.IMPORTANCEThis is the first report on the culturability and recovery of taxonomic and metabolic information of the anaerobic selenium oxyanion-reducing bacteria (SeRB) in flue gas desulfurization (FGD) wastewater. Selenium is a regulated contaminant in FGD wastewater found on average to be 3,130 µg/L that must be removed to meet EPA discharge limits of 16 µg/L (D. B. Gingerich, E. Grol, and M. S. Mauter, Environ Sci Water Res Technol 4:909-925, 2018, https://doi.org/10.1039/C8EW00264A; also see U.S. EPA EPA-821-R-20-001, 2020). Better understanding of anaerobic SeRB and the microbial community in FGD wastewater is needed to harness their full potential for the bioremediation and recovery of selenium from FGD wastewater. Optimizing the biotreatment strategies for these wastewaters promises to yield cleaner and healthier waterways and ecosystems, even as the United States undergoes a shift in its energy landscape.

Metagenomic analysis of hot spring soil for mining a novel thermostable enzybiotic

The misuse and overuse of antibiotics have contributed to a rapid emergence of antibiotic-resistant bacterial pathogens. This global health threat underlines the urgent need for innovative and novel antimicrobials. Endolysins derived from bacteriophages or prophages constitute promising new antimicrobials (so-called enzybiotics), exhibiting the ability to break down bacterial peptidoglycan (PG). In the present work, metagenomic analysis of soil samples, collected from thermal springs, allowed the identification of a prophage-derived endolysin that belongs to the N-acetylmuramoyl-L-alanine amidase type 2 (NALAA-2) family and possesses a LysM (lysin motif) region as a cell wall binding domain (CWBD). The enzyme (Ami1) was cloned and expressed in Escherichia coli, and its bactericidal and lytic activity was characterized. The results indicate that Ami1 exhibits strong bactericidal and antimicrobial activity against a broad range of bacterial pathogens, as well as against isolated peptidoglycan (PG). Among the examined bacterial pathogens, Ami1 showed highest bactericidal activity against Staphylococcus aureus sand Staphylococcus epidermidis cells. Thermostability analysis revealed a melting temperature of 64.2 ± 0.6 °C. Overall, these findings support the potential that Ami1, as a broad spectrum antimicrobial agent, could be further assessed as enzybiotic for the effective treatment of bacterial infections. KEY POINTS: • Metagenomic analysis allowed the identification of a novel prophage endolysin • The endolysin belongs to type 2 amidase family with lysin motif region • The endolysin displays high thermostability and broad bactericidal spectrum.

Clostridium brassicae sp. nov., A Strictly Anaerobic Bacterium Isolated from High-Salt Industrial Wastewater

An obligately anaerobic, Gram-positive, rod-shaped bacterium (1.8-5.5 μm long, 0.6-0.9 μm wide), designated ZC22-4T, was isolated from a pickle-processing wastewater treatment plant in Zhejiang province, P.R. China. Strain ZC22-4T grows optimally at 37-40 °C and pH 7.0 in the presence of 1% (w/v) NaCl or 2.0% (w/v) sea salts. It contained C16:0 (25.9%), C14:0 (13.6%), and C16:1 cis 9 (10.6%) as the dominant cellular fatty acid (> 10%). Polar lipids include phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), one unidentified phospholipid (PL), two unidentified glycolipids (GL), three unidentified amino phosphoglycolipids (APGL1-3), one unidentified aminoglycolipid (AGL), and one unidentified lipid (L). The genomic DNA G + C content of ZC22-4T was 28.7%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain ZC22-4T belonged to the genus Clostridium and formed a clade with the most closely related Clostridium aestuarii HY-45-18T (96.3%), Clostridium ganghwense HY-42-06T (95.9%). The average nucleotide identity and DNA-DNA hybridization values among the genomes of strain ZC22-4T and C. aestuarii HY-45-18T and C. ganghwense HY-42-06T were 75.7% and 77.3%, 21.7% and 23.0%, respectively. Based on the phenotypic, phylogenetic, and genetic data, strain ZC22-4T represents a novel species in the Clostridium cluster I, for which the name Clostridium brassicae sp. nov. is proposed. The type strain is ZC22-4T (= MCCC 1K07510T = JCM 35370T).

Description of two novel anaerobic members in the family Clostridiaceae, Anaeromonas gelatinilytica gen.nov., sp. nov., and Anaeromonas frigoriresistens sp. nov., isolated from saline lake sediment

Cells of members of the family Clostridiaceae , phylum Firmicutes , are generally obligate anaerobic rods. Strains D2Q-14T and D2Q-11T were isolated from sediment of the saline lake Manisi in the Xinjiang Uygur Autonomous Region, PR China. In this study, we employed a polyphasic approach and whole genome analysis of the two isolates. Cells of both isolates were Gram-stain-positive rods that were motile by means of flagella and could utilize sulphate, thiosulphate, elemental sulphur and nitrate as electron acceptors. Phylogenetic analyses based on 16S rRNA gene and whole genome sequences indicated that strains D2Q-14T and D2Q-11T constituted a coherent cluster affiliated to the family Clostridiaceae . In addition, genome analysis revealed that strain D2Q-14Tharboured one nonribosomal peptide synthetase gene cluster, making up 1.4 % of the entire genome. The genome-based analysis, including average nucleotide identity, average amino acid identity and in silico DNA–DNA hybridization, biochemical, phenotypic and chemotaxonomic characterization, indicated that strains D2Q-14T and D2Q-11T represented two novel species of a novel genus in the family Clostridiaceae , for which we propose the names Anaeromonas gelatinilytica gen. nov., sp. nov. and Anaeromonas frigoriresistens sp. nov., with the type strains D2Q-14T (=KCTC 15986T=MCCC 1K04634T) and D2Q-11T (=KCTC 15985T=MCCC 1K04391T), respectively.

Metatranscriptomic analysis reveals active microbes and genes responded to short-term Cr(VI) stress

Heavy metals have been severely polluting the environment. However, the response mechanism of microbial communities to short-term heavy metals stress remains unclear. In this study, metagenomics (MG) and metatranscriptomics (MT) was performed to observe the microbial response to short-term Cr(VI) stress. MG data showed that 99.1% of species were similar in the control and Cr(VI) treated groups. However, MT data demonstrated that 83% of the microbes were active in which 58.7% increased, while the relative abundance of 41.3% decreased after short-term Cr(VI) incubation. The MT results also revealed 9% of microbes were dormant in samples. Genes associated with oxidative stress, Cr(VI) transport, resistance, and reduction, as well as genes with unknown functions were 2-10 times upregulated after Cr(VI) treatment. To further confirm the function of unknown genes, two genes (314 and 494) were selected to detect the Cr(VI) resistance and reduction ability. The results showed that these genes significantly increased the Cr(VI) remediation ability of Escherichia coli. MT results also revealed an increase in the expression of some rare genera (at least two times) after Cr(VI) treatment, indicating these rare species played a crucial role in microbial response to short-term Cr(VI) stress. In summary, MT is an efficient way to understand the role of active and dormant microbes in specific environmental conditions.

A flavin-based extracellular electron transfer mechanism in diverse Gram-positive bacteria

Extracellular electron transfer (EET) describes microbial bioelectrochemical processes in which electrons are transferred from the cytosol to the exterior of the cell1. Mineral-respiring bacteria use elaborate haem-based electron transfer mechanisms2-4 but the existence and mechanistic basis of other EETs remain largely unknown. Here we show that the food-borne pathogen Listeria monocytogenes uses a distinctive flavin-based EET mechanism to deliver electrons to iron or an electrode. By performing a forward genetic screen to identify L. monocytogenes mutants with diminished extracellular ferric iron reductase activity, we identified an eight-gene locus that is responsible for EET. This locus encodes a specialized NADH dehydrogenase that segregates EET from aerobic respiration by channelling electrons to a discrete membrane-localized quinone pool. Other proteins facilitate the assembly of an abundant extracellular flavoprotein that, in conjunction with free-molecule flavin shuttles, mediates electron transfer to extracellular acceptors. This system thus establishes a simple electron conduit that is compatible with the single-membrane structure of the Gram-positive cell. Activation of EET supports growth on non-fermentable carbon sources, and an EET mutant exhibited a competitive defect within the mouse gastrointestinal tract. Orthologues of the genes responsible for EET are present in hundreds of species across the Firmicutes phylum, including multiple pathogens and commensal members of the intestinal microbiota, and correlate with EET activity in assayed strains. These findings suggest a greater prevalence of EET-based growth capabilities and establish a previously underappreciated relevance for electrogenic bacteria across diverse environments, including host-associated microbial communities and infectious disease.

Biofilm formation and potential for iron cycling in serpentinization-influenced groundwater of the Zambales and Coast Range ophiolites

Terrestrial serpentinizing systems harbor microbial subsurface life. Passive or active microbially mediated iron transformations at alkaline conditions in deep biosphere serpentinizing ecosystems are understudied. We explore these processes in the Zambales (Philippines) and Coast Range (CA, USA) ophiolites, and associated surface ecosystems by probing the relevance of samples acquired at the surface to in situ, subsurface ecosystems, and the nature of microbe-mineral associations in the subsurface. In this pilot study, we use microcosm experiments and batch culturing directed at iron redox transformations to confirm thermodynamically based predictions that iron transformations may be important in subsurface serpentinizing ecosystems. Biofilms formed on rock cores from the Zambales ophiolite on surface and in-pit associations, confirming that organisms from serpentinizing systems can form biofilms in subsurface environments. Analysis by XPS and FTIR confirmed that enrichment culturing utilizing ferric iron growth substrates produced reduced, magnetic solids containing siderite, spinels, and FeO minerals. Microcosms and enrichment cultures supported organisms whose near relatives participate in iron redox transformations. Further, a potential 'principal' microbial community common to solid samples in serpentinizing systems was identified. These results indicate collectively that iron redox transformations should be more thoroughly and universally considered when assessing the function of terrestrial subsurface ecosystems driven by serpentinization.

Inediibacterium massiliense gen. nov., sp. nov., a new bacterial species isolated from the gut microbiota of a severely malnourished infant

A novel strain, Mt12^T (=CSUR P1907 = DSM 100590), was isolated from the fecal sample of a 7-month-old girl from Senegal afflicted with severe acute malnutrition. This bacterium is a strictly anaerobic, spore-forming Gram-stain positive bacillus. The major cellular fatty acid was identified as tetradecanoic acid. Its 16S rRNA gene sequence exhibited 94.9% similarity with that of Crassaminicella profunda strain Ra1766H^T, currently the closest species with a validly published name. The draft genome of strain Mt12^T is 3,497,275-bp long with a 30.45% of G+C content. 3397 genes were predicted, including 3268 protein-coding genes and 129 RNAs, including eight 16S rRNAs. Genomic comparison with closely related species with an available genome showed a lower quantitative genomic content. The phylogenetic analysis alongside the dDDH values under 30% and phenotypic characteristics suggest that strain Mt12^T represents a new genus within the family Clostridiaceae, for which the name Inediibacterium massiliense gen. nov., sp. nov. is proposed.

Enhanced excess sludge hydrolysis and acidification in an activated sludge side-stream reactor process with single-stage sludge alkaline treatment: a pilot scale study

A pilot-scale side-stream reactor process with single-stage sludge alkaline treatment was employed to systematically investigate characteristics of excess sludge hydrolysis and acidification with alkaline treatment and evaluate feasibility of recovering a carbon source (C-source) from excess sludge to enhance nutrient removal at ambient temperature. The resulting C-source and volatile fatty acid specific yields reached 349.19 mg chemical oxygen demand (COD)/g volatile suspended solids (VSS) d^-1 and 121.3 mg COD/g VSS d^-1, respectively, the process had excellent C-source recovery potential. The propionic-to-acetic acid ratio of the recovered C-source was 3.0 times that in the influent, which beneficially enhanced biological phosphorus removal. Large populations and varieties of hydrolytic acid producing bacteria cooperated with alkaline treatment to accelerate sludge hydrolysis and acidification. Physicochemical characteristics indicated that recovered C-source was derived primarily from extracellular polymeric substances hydrolysis rather than from cells disruption during alkaline treatment. This study showed that excess sludge as carbon source was successfully recycled by alkaline treatment in the process.

Calculibacillus koreensis gen. nov., sp. nov., an anaerobic Fe(III)-reducing bacterium isolated from sediment of mine tailings

A strictly anaerobic bacterium, strain B5(T), was isolated from sediment of an abandoned coal mine in Taebaek, Republic of Korea. Cells of strain B5(T) were non-spore-forming, straight, Gram-positive rods. The optimum pH and temperature for growth were pH 7.0 and 30°C, respectively, while the strain was able to grow within pH and temperature ranges of 5.5-7.5 and 25-45°C, respectively. Growth of strain B5(T) was observed at NaCl concentrations of 0 to 6.0% (w/v) with an optimum at 3.0-4.0% (w/v). The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, an unknown phospholipid and three unknown polar lipids. Strain B5(T) grew anaerobically by reducing nitrate, nitrite, ferric-citrate, ferric-nitrilotriacetate, elemental sulfur, thiosulfate, and anthraquinone-2-sulfonate in the presence of proteinaceous compounds, organic acids, and carbohydrates as electron donors. The isolate was not able to grow by fermentation. Strain B5(T) did not grow under aerobic or microaerobic conditions. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain B5(T) is most closely related to the genus Tepidibacillus (T. fermentans STGH(T); 96.3%) and Vulcanibacillus (V. modesticaldus BR(T); 94.6%). The genomic DNA G+C content (36.9 mol%) of strain B5(T) was higher than those of T. fermentans STGH(T) (34.8 mol%) and V. modesticaldus BR(T) (34.5 mol%). Based on its phenotypic, chemotaxonomic, and phylogenetic properties, we describe a new species of a novel genus Calculibacillus, represented by strain B5(T) (=KCTC 15397(T) =JCM 19989(T)), for which we propose the name Calculibacillus koreensis gen. nov., sp. nov.

Abyssisolibacter fermentans gen. nov. sp. nov., isolated from deep sub-seafloor sediment

A Gram-staining-negative, thin rod-shaped, anaerobic bacterium designated MCWD3(T) was isolated from sediment of the deep sea in Ulleung Basin, East Sea, Korea. The ranges of temperature, pH and NaCl for growth of this strain were 15-40°C (optimum 29°C), 5.0-10.0 (optimum pH 6.5), and 1-5%, respectively. The major fatty acids were iso-C(15:0) (30%) and iso-C(15:0) dimethyl acetal (17%). The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and unidentified aminophospholipids, phospholipids, and aminolipids. The fermentation product from yeast extract was acetate. Phylogenetic analysis based on 16S rRNA genes indicated that the isolate was related to Sporosalibacterium faouarense (92.8% sequence identity), Clostridiisalibacter paucivorans (92.6%), and Brassicibacter mesophilus (92.4%). However, the isolate was differentiated from these genera by both physiological and chemotaxonomical properties. On the basis of a polyphasic taxonomic analysis, we propose that MCWD3(T) represents a novel taxon with the name Abyssisolibacter fermentans gen. nov. sp. nov.

Crassaminicella profunda gen. nov., sp. nov., an anaerobic marine bacterium isolated from deep-sea sediments

A novel, anaerobic, chemo-organotrophic bacterium, designated strain Ra1766H(T), was isolated from sediments of the Guaymas basin (Gulf of California, Mexico) taken from a depth of 2002  m. Cells were thin, motile, Gram-stain-positive, flexible rods forming terminal endospores. Strain Ra1766H(T) grew at temperatures of 25-45 °C (optimum 30 °C), pH 6.7-8.1 (optimum 7.5) and in a salinity of 5-60 g l(-1) NaCl (optimum 30 g l(-1)). It was an obligate heterotrophic bacterium fermenting carbohydrates (glucose and mannose) and organic acids (pyruvate and succinate). Casamino acids and amino acids (glutamate, aspartate and glycine) were also fermented. The main end products from glucose fermentation were acetate, butyrate, ethanol, H2 and CO2. Sulfate, sulfite, thiosulfate, elemental sulfur, fumarate, nitrate, nitrite and Fe(III) were not used as terminal electron acceptors. The predominant cellular fatty acids were C14  : 0, C16 : 1ω7, C16 : 1ω7 DMA and C16 : 0. The main polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and phospholipids. The G+C content of the genomic DNA was 33.7 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain Ra1766H(T) was affiliated to cluster XI of the order Clostridiales, phylum Firmicutes. The closest phylogenetic relative of Ra1766H(T) was Geosporobacter subterraneus (94.2% 16S rRNA gene sequence similarity). On the basis of phylogenetic inference and phenotypic properties, strain Ra1766H(T) ( = DSM 27501(T) = JCM 19377(T)) is proposed to be the type strain of a novel species of a novel genus, named Crassaminicella profunda.

Brassicibacter thermophilus sp. nov., a thermophilic bacterium isolated from coastal sediment

A novel thermophilic, obligately anaerobic bacterium, strain Cel2f(T), was isolated from a cellulolytic community enriched from coastal marine sediment. Cells were Gram-stain-negative, non-motile, non-spore-forming and rod-shaped. Optimal growth temperature and pH of strain Cel2f(T) were 55 °C and pH 7.0, respectively. NaCl was essential for the growth of strain Cel2f(T) and the strain showed enhanced growth in the presence of sea salt; the optimum sea salt concentration for growth was 7% (w/v). Thiosulfate, sulfate and sulfite were potential electron acceptors. The major fatty acids of strain Cel2f(T) were iso-C15 : 0, C16 : 0, and C18 : 0. Polar lipid analysis indicated the presence of phosphatidylethanolamine and phosphatidylglycerol. Strain Cel2f(T) contained menaquinone MK-7 as the isoprenoid quinone, and the DNA G+C content was 31.3 mol%. Phylogenetic analysis revealed that the nearest relative of strain Cel2f(T) was Brassicibacter mesophilus BM(T) with 93.8% 16S rRNA gene sequence similarity. Based on phenotypic, chemotaxonomic and phylogenetic characteristics, strain Cel2f(T) represents a novel species of genus Brassicibacter, for which the name Brassicibacter thermophilus sp. nov. is proposed. The type strain is Cel2f(T) ( = JCM 30480(T) = CGMCC 1.5200(T)).

Biogas production using anaerobic groundwater containing a subterranean microbial community associated with the accretionary prism

In a deep aquifer associated with an accretionary prism, significant methane (CH₄) is produced by a subterranean microbial community. Here, we developed bioreactors for producing CH₄ and hydrogen (H₂) using anaerobic groundwater collected from the deep aquifer. To generate CH₄, the anaerobic groundwater amended with organic substrates was incubated in the bioreactor. At first, H₂ was detected and accumulated in the gas phase of the bioreactor. After the H₂ decreased, rapid CH₄ production was observed. Phylogenetic analysis targeting 16S rRNA genes revealed that the H₂-producing fermentative bacterium and hydrogenotrophic methanogen were predominant in the reactor. The results suggested that syntrophic biodegradation of organic substrates by the H₂-producing fermentative bacterium and the hydrogenotrophic methanogen contributed to the CH₄ production. For H₂ production, the anaerobic groundwater, amended with organic substrates and an inhibitor of methanogens (2-bromoethanesulfonate), was incubated in a bioreactor. After incubation for 24 h, H₂ was detected from the gas phase of the bioreactor and accumulated. Bacterial 16S rRNA gene analysis suggested the dominance of the H₂-producing fermentative bacterium in the reactor. Our study demonstrated a simple and rapid CH₄ and H₂ production utilizing anaerobic groundwater containing an active subterranean microbial community.

Oceanirhabdus sediminicola gen. nov., sp. nov., an anaerobic bacterium isolated from sea sediment

A novel anaerobic bacterium, designated NH-JN4(T) was isolated from a sediment sample collected in the South China Sea. Cells were Gram-stain-positive, spore-forming, peritrichous and rod-shaped (0.5-1.2×2.2-7 µm). The temperature and pH ranges for growth were 22-42 °C and pH 6.0-8.5. Optimal growth occurred at 34-38 °C and pH 6.5-7.0. The NaCl concentration range for growth was 0.5-6 % (w/v) with an optimum of 2.5 %. Catalase and oxidase were not produced. Substrates which could be utilized were peptone, tryptone, yeast extract, beef extract and glycine. Main fermentation products from PYG medium were formate, acetate, butyrate and ethanol. Strain NH-JN4(T) could utilize sodium sulfite as an electron acceptor. No respiratory quinone was detected. The predominant fatty acids were anteiso-C15 : 0, C16 : 0, iso-C15 : 0, anteiso-C17 : 0 and C16 : 0 DMA. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and glycolipids. The DNA G+C content was 35.8 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain NH-JN4(T) was a member of family Clostridiaceae, and was most closely related to Clostridium limosum ATCC 25620(T), Clostridium proteolyticum DSM 3090(T), Clostridium histolyticum ATCC 19401(T) and Clostridium tepidiprofundi SG 508(T), showing 94.0, 93.0, 92.9 and 92.3 % sequence similarity, respectively. On the basis of phenotypic, genotypic and chemotaxonomic properties, strain NH-JN4(T) represents a novel species of a new genus in the family Clostridiaceae, for which the name Oceanirhabdus sediminicola gen. nov., sp. nov. is proposed. The type strain of the type species is NH-JN4(T) ( = JCM 18501(T) = CCTCC AB 2013103(T) = KCTC 15322(T)).

Brassicibacter mesophilus gen. nov., sp. nov., a strictly anaerobic bacterium isolated from food industry wastewater

A novel mesophilic, strictly anaerobic bacterium, strain BMT, was isolated from food industry wastewater. The cells were motile, non-spore-forming rods and stained Gram-negative. Growth of strain BMT was observed at 16–44 °C (optimum 37 °C) and pH 6.0–9.0 (optimum pH 7.5). The NaCl concentration range for growth was 0–8 % (optimum 1.5 %, w/v). Strain BMT was chemo-organotrophic, using a few sugars and amino acids as sole carbon and energy sources. The fermentation products from peptone-yeast extract broth were propionate, formate, acetate, ethanol and isovalerate. Indole, NH3 and H2S were produced from peptone. No respiratory quinones could be detected. The major fatty acids were iso-C15 : 0 (39.3 %), iso-C15 : 0 dimethyl acetal (10.1 %), anteiso-C15 : 0 (7.6 %), C14 : 0 (6.1 %) and C16 : 0 (5.6 %). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol and a number of unidentified aminoglycolipids, glycolipids and phospholipids. The DNA G+C content was 28.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain BMT was related to various genera of the family Clostridiaceae , and its closest relatives were Sporosalibacterium faouarense SOL3f37T (94.3 % 16S rRNA gene sequence similarity), Proteiniborus ethanoligenes GWT (92.1 %) and Clostridiisalibacter paucivorans 37HS60T (92.0 %). In recognition of its distinct phenotypic and genotypic characteristics, isolate BMT is proposed to represent a novel species of a new genus, Brassicibacter mesophilus gen. nov., sp. nov. The type strain of Brassicibacter mesophilus is BMT ( = JCM 16868T  = DSM 24659T).

Salimesophilobacter vulgaris gen. nov., sp. nov., an anaerobic bacterium isolated from paper-mill wastewater

A novel anaerobic, heterotrophic bacterium, designated strain Zn2(T), was isolated from the wastewater of a paper mill in Zhejiang, China. Cells were gram-type-positive rods, 0.5-0.8 µm wide and 2-4 µm long, and were motile by a lateral flagellum. The ranges of temperature and pH for growth were 10-50 °C and pH 6.0-9.5. Optimal growth occurred at 35 °C and pH 7.3-7.5. The strain did not require NaCl for growth, but its inclusion in the medium improved growth (optimum concentration 6 %). Substrates utilized as sole carbon sources were peptone, tryptone, Casamino acids, D-xylose, salicin, glycerol, formate, acetate and propionate. The main products of carbohydrate fermentation were acetate, formate, propionate and lactate. Elemental sulfur, thiosulfate and Fe(III) were used as electron acceptors, but sulfate, sulfite, nitrate, nitrite and Mn(IV) were not. Growth was inhibited by the addition of 10 µg ampicillin, penicillin, tetracycline or chloramphenicol ml(-1). iso-C15 : 0, C14 : 0, C16 : 0, C16 : 1 cis9 and C18 : 1 cis9 were the major fatty acids. Strain Zn2(T) did not contain any detectable menaquinones or ubiquinones. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylserine, two unknown phospholipids and four unknown glycolipids. The genomic DNA G+C content was 37 mol%, as determined by HPLC. 16S rRNA gene sequence analysis revealed that strain Zn2(T) was a member of family Clostridiaceae, and was most closely related to the type strains of Geosporobacter subterraneus, Thermotalea metallivorans and Caminicella sporogenes, showing 91.2, 90.3 and 91.1 % sequence similarity, respectively. On the basis of its phenotypic and genotypic properties, strain Zn2(T) is suggested to represent a novel species of a new genus, for which the name Salimesophilobacter vulgaris gen. nov., sp. nov. is proposed. The type strain of Salimesophilobacter vulgaris is Zn2(T) ( = DSM 24770(T)  = JCM 17796(T)).

Tepidibacter mesophilus sp. nov., a mesophilic fermentative anaerobe isolated from soil polluted by crude oil, and emended description of the genus Tepidibacter

A mesophilic, aerotolerant, endospore-forming, fermentative bacterium, designated strain B1(T), was isolated from soil polluted by crude oil in the Karamay Oil Field, China. Cells were Gram-positive, rod-shaped, 1.1-1.6 µm wide and 2.3-4.7 µm long, and were motile by means of peritrichous flagella. Growth occurred at 10-40 °C and pH 6.0-8.9; optimal growth occurred at 28-32 °C and pH 7.3. The optimal concentrations of NaCl and sea salts for growth were 0.5 and 1% (w/v), respectively. The strain was halotolerant and grew in the presence of NaCl or sea salts up to a concentration of 9% (w/v). Substrates utilized as sole carbon sources were beef extract, yeast extract, peptone, tryptone, casein, D-glucose, D-fructose, D-xylose, D-ribose, D-galactose, maltose, L-rhamnose, trehalose, L-valine, DL-alanine plus L-proline and DL-alanine plus L-glycine. The main products of glucose fermentation were ethanol and acetate. iso-C(15:0), iso-C(14:0), C(16:0) and iso-C(13:0) were the major fatty acids. 16S rRNA gene sequence analysis revealed that the isolate belongs to the genus Tepidibacter, showing 94.7 and 94.1% similarity to the type strains of Tepidibacter formicigenes and Tepidibacter thalassicus, respectively. The genomic DNA G+C content of strain B1(T) was 29.8 mol%. On the basis of its phenotypic and genotypic properties, strain B1(T) is suggested to represent a novel species of the genus Tepidibacter, for which the name Tepidibacter mesophilus sp. nov. is proposed. The type strain is B1(T) (=CGMCC 1.5148(T) =JCM 16806(T)).

Thermovenabulum gondwanense sp. nov., a thermophilic anaerobic Fe(III)-reducing bacterium isolated from microbial mats thriving in a Great Artesian Basin bore runoff channel

A strictly anaerobic, thermophilic bacterium, designated strain R270T, was isolated from microbial mats thriving in the thermal waters (66 °C) of a Great Artesian Basin bore (registered no. 17263) runoff channel. Cells of strain R270T were straight to slightly curved rods (3.50–6.00×0.75–1.00 μm) that stained Gram-positive, but possessed a Gram-negative cell-wall ultrastructure. Strain R270T grew optimally in tryptone-yeast extract-Casamino acids medium at 65 °C (growth temperature range between 50 and 70 °C) and at pH 7.0 (growth pH range between 6.0 and 9.0). In the presence of 0.02 and 0.10 % yeast extract, pyruvate and Casamino acids were the only substrates fermented from a wide spectrum of substrates tested. Fe(III), Mn(IV), thiosulfate and elemental sulfur were used as electron acceptors in the presence 0.2 % yeast extract, but not sulfate, sulfite, nitrate, nitrite or fumarate. Growth of strain R270T increased in the presence of Fe(III), which was reduced in the presence of peptone, tryptone, Casamino acids, amyl media, starch, pyruvate, H2 and CO2, but not in the presence of acetate, lactate, propionate, formate, benzoate, glycerol or ethanol. Growth and Fe(III) reduction were inhibited by chloramphenicol, streptomycin, tetracycline, penicillin, ampicillin and 2 % NaCl (w/v). The DNA G+C content of strain R270T was 41±1 mol% (T m) and phylogenetic analysis of the 16S rRNA gene indicated that this isolate was closely related to Thermovenabulum ferriorganovorum DSM 14006T (similarity value of 96.1 %) within the family ‘Thermoanaerobacteraceae’, class ‘Clostridia’, phylum ‘Firmicutes’. On the basis of the phylogenetic distance separating the two, together with differences in a number of key phenotypic characteristics, strain R270T represents a novel species of the genus Thermovenabulum, for which the name Thermovenabulum gondwanense sp. nov. is proposed; the type strain is R270T (=KCTC 5616T=DSM 21133T).

Fervidicella metallireducens gen. nov., sp. nov., a thermophilic, anaerobic bacterium from geothermal waters

A strictly anaerobic, thermophilic bacterium, designated strain AeB(T), was isolated from microbial mats colonizing a run-off channel formed by free-flowing thermal water from a bore well (registered number 17263) of the Great Artesian Basin, Australia. Cells of strain AeB(T) were slightly curved rods (2.5-6.0x1.0 mum) that stained Gram-negative and formed spherical terminal to subterminal spores. The strain grew optimally in tryptone-yeast extract-Casamino acids medium at 50 degrees C (range 37-55 degrees C) and pH 7 (range pH 5-9). Strain AeB(T) grew poorly on yeast extract (0.2 %) and tryptone (0.2 %) as sole carbon sources, which were obligately required for growth on other energy sources. Growth of strain AeB(T) increased in the presence of various carbohydrates and amino acids, but not organic acids. End products detected from glucose fermentation were ethanol, acetate, CO2 and H2. In the presence of 0.2 % yeast extract, iron(III), manganese(IV), vanadium(V) and cobalt(III) were reduced, but not sulfate, thiosulfate, sulfite, elemental sulfur, nitrate or nitrite. Iron(III) was also reduced in the presence of tryptone, peptone, Casamino acids and amyl media (Research Achievement), but not starch, xylan, chitin, glycerol, ethanol, pyruvate, benzoate, lactate, acetate, propionate, succinate, glycine, serine, lysine, threonine, arginine, glutamate, valine, leucine, histidine, alanine, aspartate, isoleucine or methionine. Growth was inhibited by chloramphenicol, streptomycin, tetracycline, penicillin, ampicillin and NaCl concentrations >2 %. The DNA G+C content was 35.4+/-1 mol%, as determined by the thermal denaturation method. 16S rRNA gene sequence analysis indicated that strain AeB(T) is a member of the family Clostridiaceae, class Clostridia, phylum 'Firmicutes', and is positioned approximately equidistantly between the genera Sarcina, Anaerobacter, Caloramator and Clostridium (16S rRNA gene similarity values of 87.8-90.9 %). On the basis of 16S rRNA gene sequence comparisons and physiological characteristics, strain AeB(T) is considered to represent a novel species in a new genus, for which the name Fervidicella metallireducens gen. nov., sp. nov. is proposed; the type strain is AeB(T) (=JCM 15555(T)=KCTC 5667(T)).