Bacterial diversity of an acid mine drainage beside the Xichú River (Mexico) accessed by culture-dependent and culture-independent approaches.

Xichú River is a Mexican river located in an environmental preservation area called Sierra Gorda Biosphere Reserve. Around it, there are tons of abandoned mine residues that represent a serious environmental issue. Sediment samples of Xichú River, visibly contaminated by flows of an acid mine drainage, were collected to study their prokaryotic diversity. The study was based on both cultural and non-cultural approaches. The analysis of total 16S rRNA gene by MiSEQ sequencing allowed to identify 182 Operational Taxonomic Units. The community was dominated by Pseudomonadota, Bacteroidota, "Desulfobacterota" and Acidobacteriota (27, 21, 19 and 16%, respectively). Different culture conditions were used focusing on the isolation of anaerobic bacteria, including sulfate-reducing bacteria (SRB) and arsenate-reducing bacteria (ARB). Finally, 16 strains were isolated. Among them, 12 were phylogenetically identified, with two strains being SRB, belonging to the genus Solidesulfovibrio ("Desulfobacterota"), while ten are ARB belonging to the genera Azospira (Pseudomonadota), Peribacillus (Bacillota), Raineyella and Propionicimonas (Actinomycetota). The isolate representative of Raineyella genus probably corresponds to a new species, which, besides arsenate, also reduces nitrate, nitrite, and fumarate.

Thermospira aquatica gen. nov., sp. nov., a novel thermophilic spirochete isolated from a Tunisian hot spring, and description of the novel family Thermospiraceae.

A novel thermophilic, anaerobic bacterium, strain F1F22T, was isolated from hot spring water collected in northern Tunisia. The cells were non-motile, Gram-negative and helical with hooked ends, 0.5×10-32 µm in size. Growth of the strain was observed at 45-70 °C (optimum, 55 °C), in 0.0-1.0 % (w/v) NaCl (optimum without NaCl) and at pH 6.5-8.5 (optimum, pH 7.5). Yeast extract was required for growth, and the strain grew on glucose, sucrose and maltose. The major fatty acids were C16:0 (40.2 %), iso-C16: 0 (30.2 %) and C16 :0 DMA (14.5 %). The genome consisted of a circular chromosome (2.5 Mb) containing 2672 predicted protein-encoding genes with a G+C content of 43.15 mol %. Based on a comparative 16S rRNA gene sequence analysis, strain F1F22T formed a deeply branching lineage within the phylum Spirochaetota, class Spirochaetia, order Brevinematales, and had only low sequence similarity to other species of the phylum (lower than 83 %). Genome-based analysis of average nucleotide identity and digital DNA-DNA hybridization of strain F1F22T with Treponema caldarium DSM 7334T, Brevinema andersonii ATCC 43811T and Spirochaeta thermophila DSM 6578T showed values between 63.26 and 63.52 %, and between 20 and 25 %. Hence, we propose strain F1F22T as a representative of a novel family (Thermospiraceae fam. nov.), genus and species of Brevinematales: Thermospira aquatica gen. nov., sp. nov. (type strain F1F22T=JCM 31314T=DSM 101182T).

Alkaliphilus serpentinus sp. nov. and Alkaliphilus pronyensis sp. nov., two novel anaerobic alkaliphilic species isolated from the serpentinite-hosted Prony Bay Hydrothermal Field (New Caledonia).

Two novel anaerobic alkaliphilic strains, designated as LacTT and LacVT, were isolated from the Prony Bay Hydrothermal Field (PBHF, New Caledonia). Cells were motile, Gram-positive, terminal endospore-forming rods, displaying a straight to curved morphology during the exponential phase. Strains LacTT and LacVT were mesophilic (optimum 30°C), moderately alkaliphilic (optimum pH 8.2 and 8.7, respectively) and halotolerant (optimum 2% and 2.5% NaCl, respectively). Both strains were able to ferment yeast extract, peptone and casamino acids, but only strain LacTT could use sugars (glucose, maltose and sucrose). Both strains disproportionated crotonate into acetate and butyrate. Phylogenetic analysis revealed that strains LacTT and LacVT shared 96.4% 16S rRNA gene sequence identity and were most closely related to A. peptidifermentans Z-7036, A. namsaraevii X-07-2 and A. hydrothermalis FatMR1 (95.7%-96.3%). Their genome size was of 3.29Mb for strain LacTT and 3.06Mb for strain LacVT with a G+C content of 36.0 and 33.9mol%, respectively. The ANI value between both strains was 73.2 %. Finally, strains LacTT (=DSM 100337=JCM 30643) and LacVT (=DSM 100017=JCM 30644) are proposed as two novel species of the genus Alkaliphilus, order Clostridiales, phylum Firmicutes, Alkaliphilus serpentinus sp. nov. and Alkaliphilus pronyensis sp. nov., respectively. The genomes of the three Alkaliphilus species isolated from PBHF were consistently detected in the PBHF chimney metagenomes, although at very low abundance, but not significantly in the metagenomes of other serpentinizing systems (marine or terrestrial) worldwide, suggesting they represent indigenous members of the PBHF microbial ecosystem.

Towards a congruent reclassification and nomenclature of the thermophilic species of the genus Pseudothermotoga within the order Thermotogales.

The phylum Thermotogae gathers thermophilic, hyperthermophic, mesophilic, and thermo-acidophilic anaerobic bacteria that are mostly originated from geothermally heated environments. The metabolic and phenotypic properties harbored by the Thermotogae species questions the evolutionary events driving the emergence of this early branch of the universal tree of life. Recent reshaping of the Thermotogae taxonomy has led to the description of a new genus, Pseudothermotoga, a sister group of the genus Thermotoga within the order Thermotogales. Comparative genomics of both Pseudothermotoga and Thermotoga spp., including 16S-rRNA-based phylogenetic, pan-genomic analysis as well as signature indel conservation, provided evidence that Thermotoga caldifontis and Thermotoga profunda species should be reclassified within the genus Pseudothermotoga and renamed as Pseudothermotoga caldifontis comb. nov. (type strain=AZM44c09T) and Pseudothermotoga profunda comb. nov. (type strain=AZM34c06T), respectively. In addition, based upon whole-genome relatedness indices and DNA-DNA Hybridization results, the reclassification of Pseudothermotoga lettingae and Pseudothermotoga subterranea as latter heterotypic synonyms of Pseudothermotoga elfii is proposed. Finally, potential genetic elements resulting from the distinct evolutionary story of the Thermotoga and Pseudothermotoga clades are discussed.

Characterization of Desulfovibrio salinus sp. nov., a slightly halophilic sulfate-reducing bacterium isolated from a saline lake in Tunisia.

A novel slightly halophilic sulfate-reducing bacterium, designated strain P1BSRT, was isolated from water of a saline lake in Tunisia. Strain P1BSRT had motile (single polar flagellum), Gram-negative, rod-shaped, non-spore-forming cells, occurring singly or in pairs. Strain P1BSRT grew at temperatures between 15 and 45 °C (optimum 40 °C), and in a pH range between 6 and 8.5 (optimum pH 6.7). The strain required NaCl for growth (1 % w/v), and tolerated high NaCl concentration (up to 12 % w/v) with an optimum of 3 % (w/v). Sulfate, thiosulfate and sulfite served as terminal electron acceptors, but not elemental sulfur, fumarate, nitrate and nitrite. Strain P1BSRT utilized lactate, pyruvate, formate, d-fructose and glycerol as carbon and energy sources. The main cellular fatty acid was C16 : 0 (50.8 %). The genomic DNA G+C content was 47.7 mol%. Phylogenetic analysis of 16S rRNA gene sequence similarity indicated that strain P1BSRT was affiliated to the genus Desulfovibrio, with the type strains Desulfovibrio salexigens (96.51 %), Desulfovibrio zosterae (95.68 %), Desulfovibrio hydrothermalis (94.81 %) and Desulfovibrio ferrireducens (94.73 %) as its closest phylogenetic relatives. On the basis of genotypic, phenotypic and phylogenetic characteristics, it is proposed to assign strain P1BSRT to a novel species of the genus Desulfovibrio, Desulfovibrio salinus sp. nov. The type strain is P1BSRT (=DSM 101510T=JCM 31065T).

Transfer of Pseudomonas pictorum Gray and Thornton 1928 to genus Stenotrophomonas as Stenotrophomonas pictorum comb. nov., and emended description of the genus Stenotrophomonas.

A polyphasic taxonomic approach including analysis of phenotypic, physiological and genotypic characteristics, 16S rRNA gene sequence and DNA-DNA hybridization analysis was used to determine the most consistent affiliation of Pseudomonas pictorum. Pseudomonas pictorum ATCC 23328T exhibited phenotypic traits of members of the genus Stenotrophomonas including cellular fatty acid composition, quinone and limited range of substrates that could be used. Antibiotic susceptibility and physiological characteristics were determined. The DNA G+C content was 65.7 mol%. Phylogenetic analysis revealed that the type strains of Stenotrophomonas terrae, Stenotrophomonashumi, Stenotrophomonasnitritireducens and Stenotrophomonasacidaminiphila were the nearest relatives (16S rRNA gene sequence similarity of 98.0 to 98.8 %). All the other type strains of species of the genus Stenotrophomonas showed high 16S rRNA gene sequence similarities (96.8 to 97.2 %). DNA-DNA hybridizations revealed 31.0, 32.0, 43.3 and 43.6 % reassociation between Pseudomonas pictorum ATCC 23328T and the type strains of S. terrae, S. humi, S. nitritireducens and S. acidaminiphila, respectively. Our overall results indicate that Pseudomonas pictorum should be transferred to the genus Stenotrophomonas as a novel species of this genus, Stenotrophomonas pictorum comb. nov. Since the original description of the genus Stenotrophomonaswas made with only one species (Stenotrophomonasmaltophilia), an emendation of the genus description is proposed in order to match better with the characteristics of the eleven novel species assigned to this genus since then.

Characterization of the first cultured representative of a Bacteroidetes clade specialized on the scavenging of cyanobacteria.

The anaerobic, mesophilic and moderately halophilic strain L21-Spi-D4T was recently isolated from the suboxic zone of a hypersaline cyanobacterial mat using protein-rich extracts of Arthrospira (formerly Spirulina) platensis as substrate. Phylogenetic analyses based on 16S rRNA genes indicated an affiliation of the novel strain with the Bacteroidetes clade MgMjR-022, which is widely distributed and abundant in hypersaline microbial mats and heretofore comprised only sequences of uncultured bacteria. Analyses of the complete genome sequence of strain L21-Spi-D4T revealed a possible specialization on the degradation of cyanobacterial biomass. Besides genes for enzymes degrading specific cyanobacterial proteins a conspicuous transport complex for the polypeptide cyanophycin could be identified that is homologous to typical polysaccharide utilization loci of Bacteroidetes. A distinct and reproducible co-occurrence pattern of environmental 16S rRNA gene sequences of the MgMjR-022 clade and cyanobacteria in the suboxic zone of hypersaline mats points to a specific dependence of members of this clade on decaying cyanobacteria. Based on a comparative analysis of phenotypic, genomic and ecological characteristics we propose to establish the novel taxa Salinivirga cyanobacteriivorans gen. nov., sp. nov., represented by the type strain L21-Spi-D4T , and Salinivirgaceae fam. nov., comprising sequences of the MgMjR-022 clade.

Serpentinicella alkaliphila gen. nov., sp. nov., a novel alkaliphilic anaerobic bacterium isolated from the serpentinite-hosted Prony hydrothermal field, New Caledonia.

A novel anaerobic, alkaliphilic, Gram-stain-positive, spore-forming bacterium was isolated from a carbonaceous hydrothermal chimney in Prony Bay, New Caledonia. This bacterium, designated strain 3bT, grew at temperatures from 30 to 43 °C (optimum 37 °C) and at pH between 7.8 and 10.1 (optimum 9.5). Added NaCl was not required for growth (optimum 0-0.2 %, w/v), but was tolerated at up to 4 %. Yeast extract was required for growth. Strain 3bT utilized crotonate, lactate and pyruvate, but not sugars. Crotonate was dismutated to acetate and butyrate. Lactate was disproportionated to acetate and propionate. Pyruvate was degraded to acetate plus trace amounts of hydrogen. Growth on lactate was improved by the addition of fumarate, which was used as an electron acceptor and converted to succinate. Sulfate, thiosulfate, elemental sulfur, sulfite, nitrate, nitrite, FeCl3, Fe(III)-citrate, Fe(III)-EDTA, chromate, arsenate, selenate and DMSO were not used as terminal electron acceptors. The G+C content of the genomic DNA was 33.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the isolate is a member of the family Clostridiaceae, order Clostridiales within the phylum Firmicutes. Strain 3bT was most closely related to 'Alkaliphilus hydrothermalis' FatMR1T (92.2 % 16S rRNA gene sequence similarity), and was positioned approximately equidistantly between the genera Alkaliphilus, Anaerovirgula and Natronincola. On the basis of phylogenetic, genetic, chemotaxonomic and physiological properties, strain 3bT is proposed to represent a novel species of a new genus, for which the name Serpentinicella alkaliphila gen. nov., sp. nov. is proposed. The type strain of Serpentinicella alkaliphila is 3bT (=DSM 100013T=JCM 30645T).

Desulfotomaculum aquiferis sp. nov. and Desulfotomaculum profundi sp. nov., isolated from a deep natural gas storage aquifer.

Two novel strictly anaerobic bacteria, strains Bs105T and Bs107T, were isolated from a deep aquifer-derived hydrocarbonoclastic community. The cells were rod-shaped, not motile and had terminal spores. Phylogenetic affiliation and physiological properties revealed that these isolates belong to two novel species of the genus Desulfotomaculum. Optimal growth temperatures for strains Bs105T and Bs107T were 42 and 45 °C, respectively. The estimated G+C content of the genomic DNA was 42.9 and 48.7 mol%. For both strains, the major cellular fatty acid was palmitate (C16 : 0). Specific carbon fatty acid signatures of Gram-positive bacteria (iso-C17 : 0) and sulfate-reducing bacteria (C17 : 0cyc) were also detected. An insertion was revealed in one of the two 16S rRNA gene copies harboured by strain Bs107T. Similar insertions have previously been highlighted among moderately thermophilic species of the genus Desulfotomaculum. Both strains shared the ability to oxidize aromatic acids (Bs105T: hydroquinone, acetophenone, para-toluic acid, 2-phenylethanol, trans-cinnamic acid, 4-hydroxybenzaldehyde, benzyl alcohol, benzoic acid 4-hydroxybutyl ester; Bs107T: ortho-toluic acid, benzoic acid 4-hydroxybutyl ester). The names Desulfotomaculum aquiferis sp. nov. and Desulfotomaculum profundi sp. nov. are proposed for the type strains Bs105T (=DSM 24088T=JCM 31386T) and Bs107T (=DSM 24093T=JCM 31387T).

Novel serine keratinase from Caldicoprobacter algeriensis exhibiting outstanding hide dehairing abilities.

The current paper reports on the purification of an extracellular thermostable keratinase (KERCA) produced from Caldicoprobacter algeriensis strain TH7C1(T), a thermophilic, anaerobic bacterium isolated from a hydrothermal hot spring in Algeria. The maximum keratinase activity recorded after 24-h of incubation at 50 °C was 21000 U/ml. The enzyme was purified by ammonium sulfate precipitation-dialysis and heat treatment (2h at 50 °C) followed by UNO Q-6 FPLC anion exchange chromatography, and submitted to biochemical characterization assays. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) analysis revealed that the purified enzyme was a monomer with a molecular mass of 33246.10 Da. The sequence of the 23 N-terminal residues of KERCA showed high homology with those of bacterial keratinases. Optimal activity was achieved at pH 7 and 50 °C. The enzyme was completely inhibited by phenylmethanesulfonyl fluoride (PMSF) and diiodopropyl fluorophosphates (DFP), which suggests that it belongs to the serine keratinase family. KERCA displayed higher levels of hydrolysis and catalytic efficiency than keratinase KERQ7 from Bacillus tequilensis strain Q7. These properties make KERCA a potential promising and eco-friendly alternative to the conventional chemicals used for the dehairing of goat, sheep, and bovine hides in the leather processing industry.

Mobilisporobacter senegalensis gen. nov., sp. nov., an anaerobic bacterium isolated from tropical shea cake.

A Gram-stain positive, endospore-forming, strictly anaerobic bacterium, designated strain Gal1T, was isolated from shea cake, a waste material from the production of shea butter, originating from Saraya, Senegal. The cells were rod-shaped, slightly curved, and motile with peritrichous flagella. The strain was oxidase-negative and catalase-negative. Growth was observed at temperatures ranging from 15 to 45 °C (optimum 30 °C) and at pH 6.5-9.3 (optimum pH 7.8). The salinity range for growth was 0-3.5 % NaCl (optimum 1 %). Yeast extract was required for growth. Strain Gal1T fermented various carbohydrates such as mannose, mannitol, arabinose, cellobiose, fructose, glucose, maltose, sucrose, trehalose and lactose and the major end-products were ethanol and acetate. The only major cellular fatty acid was C16 : 0 (19.6 %). The DNA base G+C content of strain Gal1T was 33.8 mol%. Analysis of the 16S rRNA gene sequence of the isolate indicated that this strain was related to Mobilitalea sibirica DSM 26468T with 94.27 % similarity, Clostridium populeti ATTC 35295T with 93.94 % similarity, and Clostridium aminovalericum DSM 1283T and Anaerosporobacter mobilis DSM 15930T with 93.63 % similarity. On the basis of phenotypic characteristics, phylogenetic analysis and the results of biochemical and physiological tests, strain Gal1T was clearly distinguished from closely related genera, and strain Gal1T can be assigned to a novel species of a new genus for which the name Mobilisporobacter senegalensis gen. nov., sp. nov. is proposed. The type strain is Gal1T ( = DSM 26537T = JCM 18753T).

Thermanaeromonas burensis sp. nov., a thermophilic anaerobe isolated from a subterranean clay environment.

A strictly anaerobic, thermophilic and halotolerant strain, designated IA106T, was isolated from the seepage water collected in a metal biocorrosion test at a depth of 490 m, in a 130-160 m thick, subterranean Callovo-Oxfordian clay formation (158-152 million years old) in northern France. This geological formation has been selected as the potential host rock for the French high-level nuclear waste repository. Cells of strain IA106T stained Gram-positive and were non-motile, spore-forming, straight rods (0.5 × 2-6 µm). The five major fatty acids were C16 : 0 (15.9 %), C18 : 0 (15.4 %), iso-C17 : 1 I and/or anteiso-C17 : 1 B(14.8 %), iso-C17 : 0 (14.7 %) and iso-C15 : 0 (13.0 %). Growth was observed at temperatures ranging from 55 to 70 °C and at pH 5.5-9. The salinity range for growth was 0-20 g NaCl 1- 1. Yeast extract was required for growth. Strain IA106T was able to grow on lactate and various sugars in the presence of thiosulfate as electron acceptor. Sulfate, sulfite, elemental sulfur, fumarate, nitrate and nitrite were not reduced. The DNA G+C content was 60.2 mol%. 16S rRNA gene sequence analysis indicated that strain IA106T belonged to the family Thermoanaerobacteraceae, class Clostridia, phylum Firmicutes, and was most closely related to Thermanaeromonas toyohensis DSM 14490T (95.16 % 16S rRNA gene sequence similarity). On the basis of 16S rRNA gene sequence comparisons and physiological characteristics, strain IA106T represents a novel species of the genus Thermanaeromonas, for which the name Thermanaeromonas burensis sp. nov. is proposed. The type strain is IA106T ( = DSM 26576T = JCM 18718T).

Complete genome sequence and description of Salinispira pacifica gen. nov., sp. nov., a novel spirochaete isolated form a hypersaline microbial mat.

During a study of the anaerobic microbial community of a lithifying hypersaline microbial mat of Lake 21 on the Kiritimati atoll (Kiribati Republic, Central Pacific) strain L21-RPul-D2(T) was isolated. The closest phylogenetic neighbor was Spirochaeta africana Z-7692(T) that shared a 16S rRNA gene sequence identity value of 90% with the novel strain and thus was only distantly related. A comprehensive polyphasic study including determination of the complete genome sequence was initiated to characterize the novel isolate. Cells of strain L21-RPul-D2(T) had a size of 0.2 - 0.25 × 8-9 µm, were helical, motile, stained Gram-negative and produced an orange carotenoid-like pigment. Optimal conditions for growth were 35°C, a salinity of 50 g/l NaCl and a pH around 7.0. Preferred substrates for growth were carbohydrates and a few carboxylic acids. The novel strain had an obligate fermentative metabolism and produced ethanol, acetate, lactate, hydrogen and carbon dioxide during growth on glucose. Strain L21-RPul-D2(T) was aerotolerant, but oxygen did not stimulate growth. Major cellular fatty acids were C14:0, iso-C15:0, C16:0 and C18:0. The major polar lipids were an unidentified aminolipid, phosphatidylglycerol, an unidentified phospholipid and two unidentified glycolipids. Whole-cell hydrolysates contained L-ornithine as diagnostic diamino acid of the cell wall peptidoglycan. The complete genome sequence was determined and annotated. The genome comprised one circular chromosome with a size of 3.78 Mbp that contained 3450 protein-coding genes and 50 RNA genes, including 2 operons of ribosomal RNA genes. The DNA G + C content was determined from the genome sequence as 51.9 mol%. There were no predicted genes encoding cytochromes or enzymes responsible for the biosynthesis of respiratory lipoquinones. Based on significant differences to the uncultured type species of the genus Spirochaeta, S. plicatilis, as well as to any other phylogenetically related cultured species it is suggested to place strain L21-RPul-D2(T) (=DSM 27196(T) = JCM 18663(T)) in a novel species and genus, for which the name Salinispira pacifica gen. nov., sp. nov. is proposed.

Acetoanaerobium pronyense sp. nov., an anaerobic alkaliphilic bacterium isolated from a carbonate chimney of the Prony Hydrothermal Field (New Caledonia).

A novel anaerobic bacterial strain, ST07-YET, was isolated from a carbonate chimney of the Prony Hydrothermal Field (PHF) in New Caledonia. Cells were Gram-stain-positive, straight rods (0.7-0.8 × 3.0-5.0 µm) and motile by means of lateral flagella. Strain ST07-YET was mesophilic (optimum 35 °C), moderately alkaliphilic and halotolerant (optimum pH 8.7 and 5 g l- 1 NaCl). Elemental sulfur, sulfate, thiosulfate, sulfite, nitrate and nitrite were not used as terminal electron acceptors. Yeast extract, peptone, tryptone, Casamino acids, crotonate, pyruvate, galactose, maltose, sucrose, ribose, trehalose and glucose were used as carbon sources. Glucose fermentation led to acetate, H2 and CO2 formation. Arginine, serine, histidine, lysine, methionine and cysteine improved growth, but the Stickland reaction was negative for the combinations of amino acids tested. The major metabolic products from yeast extract fermentation were H2, CO2, acetate, butyrate, isobutyrate, isovalerate and propionate. The predominant cellular fatty acids were C16 : 0, C16 : 1cis9, C14 : 0 and C16 : 1cis7 (>5 % of total fatty acids). The G+C content of the genomic DNA was 32.9 mol%. Phylogenetic analysis revealed that strain ST07-YET was most closely related to Clostridium sticklandii DSM 519T and Acetoanaerobium noterae NOT-3T (96.7 % and 96.8 % 16S rRNA gene sequence similarity, respectively). On the basis of phylogenetic, chemotaxonomic and physiological properties, strain ST07-YET is proposed to represent a novel species of the genus Acetoanaerobium (order Clostridiales, phylum Firmicutes) with the name Acetoanaerobium pronyense sp. nov. The type strain is ST07-YET ( = DSM 27512T = JCM 19400T).

Fusibacter bizertensis sp. nov., isolated from a corroded kerosene storage tank.

Strain LTF Kr01(T), a novel mesophilic, anaerobic, halotolerant, rod-shaped bacterium, was isolated from a drain at the bottom of a corroded kerosene storage tank of the Société Tunisienne des Industries de Raffinage (STIR), Bizerte, northern Tunisia. Cells were Gram-positive-staining rods, occurred singly or in pairs, and were motile by one lateral flagellum. Strain LTF Kr01(T) grew at temperatures between 15 and 40 °C (optimum 30 °C), between pH 5.5 and 8.2 (optimum pH 7.2) and at NaCl concentrations between 0 and 50 g l(-1) (optimum 5 g l(-1)). It reduced thiosulfate and elemental sulfur into sulfide, but did not reduce sulfate or sulfite. It utilized a wide range of carbohydrates (cellobiose, d-glucose, d-fructose, d-mannitol, d-ribose, sucrose, d-xylose, maltose, d-galactose, starch and trehalose) and produced acetate, CO2 and H2 as end products from glucose fermentation. The DNA G+C content was 37.4 mol%. The predominant cellular fatty acids were C14:0 and C16:0. Phylogenetic analysis of the 16S rRNA gene sequence suggested that Fusibacter tunisiensis was the closest relative of strain LTF Kr01(T) (gene sequence similarity of 94.6%). Based on phenotypic, phylogenetic and genotypic taxonomic characteristics, strain LTF Kr01(T) is proposed to represent a novel species of the genus Fusibacter, order Clostridiales, for which the name Fusibacter bizertensis sp. nov. is proposed. The type strain is LTF Kr01(T) ( = DSM 28034(T) = JCM 19376(T)).

Partial characterization of xylanase produced by Caldicoprobacter algeriensis, a new thermophilic anaerobic bacterium isolated from an Algerian hot spring.

To date, xylanases have expanded their use in many processing industries, such as pulp, paper, food, and textile. This study aimed the production and partial characterization of a thermostable xylanase from a novel thermophilic anaerobic bacterium Caldicoprobacter algeriensis strain TH7C1(T) isolated from a northeast hot spring in Algeria. The obtained results showed that C. algeriensis xylanase seems not to be correlated with the biomass growth profile whereas the maximum enzyme production (140.0 U/ml) was recorded in stationary phase (18 h). The temperature and pH for optimal activities were 70 °C and 11.0, respectively. The enzyme was found to be stable at 50, 60, 70, and 80 °C, with a half-life of 10, 9, 8, and 4 h, respectively. Influence of metal ions on enzyme activity revealed that Ca(+2) enhances greatly the relative activity to 151.3 %; whereas Hg(2+) inhibited significantly the enzyme. At the best of our knowledge, this is the first report on the production of xylanase by the thermophilic bacterium C. algeriensis. This thermo- and alkaline-tolerant xylanase could be used in pulp bleaching process.

Halomonas olivaria sp. nov., a moderately halophilic bacterium isolated from olive-processing effluents.

A moderately halophilic, Gram-stain-negative, non-sporulating bacterium designed as strain TYRC17(T) was isolated from olive-processing effluents. The organism was a straight rod, motile by means of peritrichous flagella and able to respire both oxygen and nitrate. Growth occurred with 0-25 % (w/v) NaCl (optimum, 7 %), at pH 5-11 (optimum, pH 7.0) and at 4-50 °C (optimally at 35 °C). It accumulated poly-ß-hydroxyalkanoate granules and produced exopolysaccharides. The predominant fatty acids were C18 : 1ω7c, C16 : 1ω7c and C16 : 0. Ubiquinone 9 (Q-9) was the only respiratory quinone. The DNA G+C content of TYRC17(T) was 53.9 mol%. Phylogenetic analyses of 16S rRNA gene sequences revealed that the strain represents a member of the genus Halomonas and more precisely of the subgroup containing Halomonas sulfidaeris, H. titanicae, H. variabilis, H. zhanjiangensis, H. alkaliantarctica, H. boliviensis and H. neptunia. TYRC17(T) showed high 16S-rRNA sequence identities in particular with the three last species listed (99.4-99.5 %). A multilocus sequence analysis (MLSA) using the 23S rRNA, gyrB, rpoD and secA genes allowed clarifying the phylogenetic position of TYRC17(T). This, combined with the level of DNA-DNA hybridization between TYRC17(T) and its closest relatives ranging from 21.6 % to 48.4 %, indicated that TYRC17(T) did not represent any of these species. On the basis of phenotypic and genotypic characteristics, and also genomic and phylogenetic evidence, it was concluded that strain TYRC17(T) represented a novel species of the genus Halomonas. The name Halomonas olivaria sp. nov. is proposed with TYRC17(T) ( = DSM 19074(T) = CCUG 53850B(T)) as the type strain.

Desulfosporosinus burensis sp. nov., a spore-forming, mesophilic, sulfate-reducing bacterium isolated from a deep clay environment.

A novel anaerobic, gram-positive, spore-forming, curved rod-shaped, mesophilic and sulfate-reducing bacterium was isolated from pore water collected in a borehole at -490 m in Bure (France). This strain, designated BSREI1(T), grew at temperatures between 5 °C and 30 °C (optimum 25 °C) and at a pH between 6 and 8 (optimum 7). It did not require NaCl for growth, but tolerated it up to 1.5 % NaCl. Sulfate, thiosulfate and elemental sulfur were used as terminal electron acceptors. Strain BSREI1(T) used crotonate, formate, lactate, pyruvate, fructose, glycerol and yeast extract as electron donors in the presence of sulfate. The sole quinone was MK-7. The G+C content of the genomic DNA was 43.3 mol%. Strain BSREI1(T) had the type strains of Desulfosporosinus lacus (16S rRNA gene sequence similarity of 96.83 %), Desulfosporosinus meridiei (96.31 %) and Desulfosporosinus hippei (96.16 %) as its closest phylogenetic relatives. On the basis of phylogenetic and physiological properties, strain BSREI1(T) is proposed as a representative of a novel species of the genus Desulfosporosinus, Desulfosporosinus burensis sp. nov.; the type strain is BSREI1(T) ( = DSM 24089(T) = JCM 17380(T)).

Magnetotactic bacteria in microcosms originating from the French Mediterranean Coast subjected to oil industry activities.

Magnetotactic bacteria (MTB) mineralize nanosized magnetite or greigite crystals within cells and thus play an important role in the biogeochemical process. Despite decades of research, knowledge of MTB distribution and ecology, notably in areas subjected to oil industry activities, is still limited. In the present study, we investigated the presence of MTB in the Gulf of Fos, French Mediterranean coast, which is subjected to intensive oil industry activities. Microcosms containing sediments/water (1:2, v/v) from several sampling sites were monitored over several weeks. The presence of MTB was revealed in five of eight sites. Diverse and numerous MTB were revealed particularly from one site (named CAR), whilst temporal variations of a homogenous magnetotactic cocci population was shown within the LAV site microcosm over a 4-month period. Phylogenetic analysis revealed that they belonged to Alphaproteobacteria, and a novel genus from the LAV site was evidenced. Among the physicochemical parameters measured, a correlation was shown between the variation of MTB abundance in microcosms and the redox state of sulphur compounds.

Isolation and characterization of Thermanaerothrix daxensis gen. nov., sp. nov., a thermophilic anaerobic bacterium pertaining to the phylum "Chloroflexi", isolated from a deep hot aquifer in the Aquitaine Basin.

A new strictly anaerobic thermophilic multicellular filamentous bacterium (0.2-0.3µm×>100µm), designated GNS-1(T), was isolated from a deep hot aquifer in France. It was non-motile, and stained Gram-negative. Optimal growth was observed at 65°C, pH 7.0, and 2gL(-1) of NaCl. Strain GNS-1(T) was chemoorganotrophic fermenting ribose, glucose, galactose, arabinose, fructose, mannose, maltose, sucrose, xylose, raffinose, pyruvate, and xylan. Yeast extract was required for growth. The end products of glucose fermentation were lactate, acetate, CO(2), and H(2). The G+C content of the DNA was 57.6mol%. Its closest phylogenetic relative was Bellilinea caldifistulae with 92.5% similarity. Based on phylogenetic, genotypic and phenotypic characteristics, strain GNS-1(T) (DSM 23592(T), JCM 16980(T)) is proposed to be assigned to a novel species of a novel genus within the class Anaerolineae (subphylum I), phylum "Chloroflexi", Thermanaerothrix daxensis gen. nov., sp. nov. The GenBank accession number is HM596746.