Williamwhitmania taraxaci gen. nov., sp. nov., a proteolytic anaerobe with a novel type of cytology from Lake Untersee in Antarctica, description of Williamwhitmaniaceae fam. nov., and emendation of the order Bacteroidales Krieg 2012.

The proteolytic bacterium strain A7P-90mT was isolated from Lake Untersee, Antarctica. The anoxic water was collected from a perennially sealed (~100 millennia) glacial ice lake. Gram-stain-negative cells were 0.18-0.3×8.0-25.0 µm in size, straight, slender rods with unusual gliding motility by external, not previously reported, organelles named here as antiae. At the end of stationary phase of growth, spheroplasts were terminally formed and the cells resembled dandelions. After death, cells were helical. The isolate was an athalassic, strictly anaerobic and catalase-negative proteolytic chemoorganotroph. It was moderately psychrophilic with a temperature range for growth of 3-26 °C and an optimum at 22-23 °C. The pH range for growth was 5.5-7.8 with an optimum at 6.9. Major cellular fatty acids were branched pentadecanoic and tridecanoic acids, and saturated tetradecanoic acids. The quinone system comprised menaquinone MK-7. The strain was sensitive to all checked antibiotics and ascorbic acid. The G+C content of the genomic DNA was 42.6 mol%. Based on average nucleotide identity, average amino acid identity and phylogenetic analyses, the novel isolate was placed within a unique phylogenetic cluster distant from all eight families in the order Bacteroidales and formed a novel family with the proposed name Williamwhitmaniaceae fam. nov. The description of the order Bacteroidales was emended accordingly. The name Williamwhitmania taraxaci gen. nov., sp. nov. is proposed for the new genus and novel species with the type strain A7P-90mT (=DSM 100563T=JCM 30888T). The complete draft genome sequence was deposited at the Joint Genomes Institute (JGI) under number IMG OID 2654588148 and in SRA listed as SRP088197.

Sanguibacter gelidistatuariae sp. nov., a novel psychrotolerant anaerobe from an ice sculpture in Antarctica, and emendation of descriptions of the family Sanguibacteraceae, the genus Sanguibacter and species S. antarcticus, S. inulinus, S. kedieii, S. marinus, S. soli and S. suarezii.

A novel psychrotolerant bacterium, strain ISLP-3T, was isolated from a sample of naturally formed ice sculpture on the shore of Lake Podprudnoye in Antarctica. Cells were motile, stained Gram-positive, non-spore-forming, straight or slightly curved rods with the shape of a baseball bat. The new isolate was facultatively anaerobic and catalase-positive. Growth occurred at 3-35 °C with an optimum at 22-24 °C, 0-2 % (w/v) NaCl with an optimum at 0.3 % and pH 6.2-9.5 with an optimum at pH 7.5. Strain ISLP-3T grew on several carbon sources, with the best growth on cellobiose. The isolate possessed ureolytic activity but growth was inhibited by urea. The strain was sensitive to: ampicillin, gentamycin, kanamycin rifampicin, tetracycline and chloramphenicol. Major fatty acids were: anteiso-C15 : 0, iso-C16 : 0, C16 : 0, C14 : 0 and iso-C15 : 0. The predominant menaquinone was MK-9(H4). The genomic G+C content was 69.5 mol%. The 16S rRNA gene showed 99 % sequence similarity to that of Sanguibacter suarezii ST-26T, but their recA genes shared ≤91 % sequence similarity, suggesting that this new isolate represents a novel species within the genus Sanguibacter. This conclusion was supported by average nucleotide identity, which was ≤91 % to the most closely related strain. The name Sanguibacter gelidistatuariae sp. nov. is proposed for the novel species with the type strain ISLP-3T=ATCC TSD-17T=DSM 100501T=JCM 30887T). The complete genome draft sequence of ISLP-3T was deposited under IMG OID 2657245272. Emendments to the descriptions of related taxa have been made based on experimental data from our comparative analysis.

Proteocatella sphenisci gen. nov., sp. nov., a psychrotolerant, spore-forming anaerobe isolated from penguin guano.

A novel, obligately anaerobic, psychrotolerant bacterium, designated strain PPP2T, was isolated from guano of the Magellanic penguin (Spheniscus magellanicus) in Chilean Patagonia. Cells were Gram-stain-positive, spore-forming, straight rods (0.7-0.8x3.0-5.0 microm) that were motile by means of peritrichous flagella. Growth was observed at pH 6.7-9.7 (optimum pH 8.3) and 2-37 degrees C (optimum 29 degrees C). Growth was observed between 0 and 4% (w/v) NaCl with optimum growth at 0.5% (w/v). Strain PPP2T was a catalase-negative chemo-organoheterotroph that was capable of fermentative metabolism. Peptone, bacto-tryptone, Casamino acids, oxalate, starch, chitin and yeast extract were utilized as substrates. The major metabolic products were acetate, butyrate and ethanol. Strain PPP2T was resistant to ampicillin, but sensitive to tetracycline, chloramphenicol, rifampicin, kanamycin, vancomycin and gentamicin. The DNA G+C content of strain PPP2T was 39.5 mol%. Phylogenetic analysis revealed that strain PPP2T was related most closely to Clostridium sticklandii SR (approximately 90% 16S rRNA gene sequence similarity). On the basis of phylogenetic analysis and phenotypic characteristics, strain PPP2T is considered to represent a novel species of a new genus, for which the name Proteocatella sphenisci gen. nov., sp. nov. is proposed. The type strain of Proteocatella sphenisci is PPP2T (=ATCC BAA-755T=JCM 12175T=CIP 108034T).

Spirochaeta dissipatitropha sp. nov., an alkaliphilic, obligately anaerobic bacterium, and emended description of the genus Spirochaeta Ehrenberg 1835.

A novel obligately anaerobic, mesophilic, alkaliphilic spirochaete, strain ASpC2(T), was isolated from an anaerobic sediment of alkaline, hypersaline Owens Lake in California, USA. The Gram-negative cells are motile, helical in shape and 0.23 x 8.0-18.0 mum. Growth occurs within the following ranges: 13-41 degrees C, with optimal growth at 35 degrees C; 1-3 % (w/v) NaCl, with optimal growth at 2 % (w/v) NaCl; and pH 7.8-10.5, with optimal growth at pH 10.0. The novel isolate is strictly alkaliphilic and requires high concentrations of carbonate ions in the medium. It utilizes some sugars, some organic acids, some amino acids, Casamino acids, yeast extract and peptone. The main end products of glucose fermentation are CO(2) and acetate. Strain ASpC2(T) is resistant to kanamycin and rifampicin, but sensitive to ampicillin, chloramphenicol, gentamicin and tetracycline. The DNA G+C content of the new isolate is 43.8 mol%, its genome size is 6 x 10(8) Da and the melting temperature of its genomic DNA is 71 degrees C. DNA-DNA hybridization experiments demonstrated 46 % similarity with the phylogenetically most closely related species, Spirochaeta asiatica Z-7591(T). On the basis of physiological and molecular properties, the new isolate belongs taxonomically to a novel species within the genus Spirochaeta, for which the name Spirochaeta dissipatitropha sp. nov. is proposed (type strain, ASpC2(T)=ATCC BAA-1083(T)=JCM 12856(T)). S. dissipatitropha ASpC2(T) is the second strain in the genus (after Spirochaeta smaragdinae SEBR 4228(T)) that is able to use proteolysis products as the sole energy source, and additional tests have shown that other halo-alkaliphilic spirochaetes (Spirochaeta americana, Spirochaeta alkalica and Spirochaeta africana) are also able to grow on yeast extract alone; therefore, an emended description for the genus Spirochaeta is given.

Microbial extremophiles at the limits of life.

Prokaryotic extremophiles were the first representatives of life on Earth and they are responsible for the genesis of geological structures during the evolution and creation of all currently known ecosystems. Flexibility of the genome probably allowed life to adapt to a wide spectrum of extreme environments. As a result, modern prokaryotic diversity formed in a framework of physico-chemical factors, and it is composed of: thermophilic, psychrophilic, acidophilic, alkaliphilic, halophilic, barophilic, and radioresistant species. This artificial systematics cannot reflect the multiple actions of different environmental factors since one organism could unite characteristics of several extreme-groups. In this review we show the current status of studies in all fields of extremophiles and summarize the limits of life for different species of microbial extremophiles. We also discuss the finding of extremophiles from unusual places such as soils, and briefly review recent studies of microfossils in meteorites in the context of the significance of microbial extremophiles to Astrobiology.

Thermococcus thioreducens sp. nov., a novel hyperthermophilic, obligately sulfur-reducing archaeon from a deep-sea hydrothermal vent.

A hyperthermophilic, sulfur-reducing, organo-heterotrophic archaeon, strain OGL-20P(T), was isolated from 'black smoker' chimney material from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge (36.2 degrees N, 33.9 degrees W). The cells of strain OGL-20P(T) have an irregular coccoid shape and are motile with a single flagellum. Growth was observed within a pH range of 5.0-8.5 (optimum pH 7.0), an NaCl concentration range of 1-5 % (w/v) (optimum 3 %) and a temperature range of 55-94 degrees C (optimum 83-85 degrees C). The novel isolate is strictly anaerobic and obligately dependent upon elemental sulfur as an electron acceptor, but it does not reduce sulfate, sulfite, thiosulfate, Fe(III) or nitrate. Proteolysis products (peptone, bacto-tryptone, Casamino acids and yeast extract) are utilized as substrates during sulfur reduction. Strain OGL-20P(T) is resistant to ampicillin, chloramphenicol, kanamycin and gentamicin, but sensitive to tetracycline and rifampicin. The G+C content of the DNA is 52.9 mol%. The 16S rRNA gene sequence analysis revealed that strain OGL-20P(T) is closely related to Thermococcus coalescens and related species, but no significant homology by DNA-DNA hybridization was observed between those species and the new isolate. On the basis of physiological and molecular properties of the new isolate, we conclude that strain OGL-20P(T) represents a new separate species within the genus Thermococcus, for which we propose the name Thermococcus thioreducens sp. nov. The type strain is OGL-20P(T) (=JCM 12859(T)=DSM 14981(T)=ATCC BAA-394(T)).

Anaerovirgula multivorans gen. nov., sp. nov., a novel spore-forming, alkaliphilic anaerobe isolated from Owens Lake, California, USA.

A novel, alkaliphilic, obligately anaerobic bacterium, strain SCAT, was isolated from mud sediments of a soda lake in California, USA. The rod-shaped cells were motile, Gram-positive, formed spores and were 0.4-0.5x2.5-5.0 microm in size. Growth occurred within the pH range 6.7-10.0 and was optimal at pH 8.5. The temperature range for growth was 10-45 degrees C, with optimal growth at 35 degrees C. NaCl was required for growth. Growth occurred at 0.5-9.0% (w/v) NaCl and was optimal at 1-2% (w/v). The novel isolate was a catalase-negative chemo-organoheterotroph that fermented sugars, proteolysis products, some organic and amino acids, glycerol, d-cellobiose and cellulose. It was also capable of growth by the Stickland reaction. Strain SCAT was sensitive to tetracycline, chloramphenicol, rifampicin and gentamicin, but it was resistant to ampicillin and kanamycin. The G+C content of the genomic DNA was 34.2 mol%. Major fatty acid components were C14:0, iso-C15:0, C16:1omega9c and C16:0. 16S rRNA gene sequence analysis of strain SCAT showed a similarity of approximately 97% with the type strains of Clostridium formicaceticum and Clostridium aceticum in clostridial cluster XI and a similarity of less than 94.2% to any other recognized Clostridium species and those of related genera in this cluster. Strain SCAT was clearly differentiated from C. formicaceticum and C. aceticum based on comparison of their phenotypic properties and fatty acid profiles, as well as low levels of DNA-DNA relatedness between strain SCAT and the type strains of these two species. Therefore, strain SCAT is considered to represent a novel species of a new genus, Anaerovirgula multivorans gen. nov., sp. nov., in clostridial cluster XI. The type strain is SCAT (=ATCC BAA-1084T=JCM 12857T=DSM 17722T=CIP 107910T).

Trichococcus patagoniensis sp. nov., a facultative anaerobe that grows at -5 degrees C, isolated from penguin guano in Chilean Patagonia.

A novel, extremely psychrotolerant, facultative anaerobe, strain PmagG1(T), was isolated from guano of Magellanic penguins (Spheniscus magellanicus) collected in Chilean Patagonia. Gram-variable, motile cocci with a diameter of 1.3-2.0 mum were observed singularly or in pairs, short chains and irregular conglomerates. Growth occurred within the pH range 6.0-10.0, with optimum growth at pH 8.5. The temperature range for growth of the novel isolate was from -5 to 35 degrees C, with optimum growth at 28-30 degrees C. Strain PmagG1(T) did not require NaCl, as growth was observed in the presence of 0-6.5 % NaCl with optimum growth at 0.5 % (w/v). Strain PmagG1(T) was a catalase-negative chemo-organoheterotroph that used sugars and some organic acids as substrates. The metabolic end products were lactate, formate, acetate, ethanol and CO(2). Strain PmagG1(T) was sensitive to ampicillin, tetracycline, chloramphenicol, rifampicin, kanamycin and gentamicin. The G+C content of its genomic DNA was 45.8 mol%. 16S rRNA gene sequence analysis showed 100 % similarity of strain PmagG1(T) with Trichococcus collinsii ATCC BAA-296(T), but DNA-DNA hybridization between them demonstrated relatedness values of <45+/-1 %. Another phylogenetically closely related species, Trichococcus pasteurii, showed 99.85 % similarity by 16S rRNA sequencing and DNA-DNA hybridization showed relatedness values of 47+/-1.5 %. Based on genotypic and phenotypic characteristics, the novel species Trichococcus patagoniensis sp. nov. is proposed, with strain PmagG1(T) (=ATCC BAA-756(T)=JCM 12176(T)=CIP 108035(T)) as the type strain.

Carnobacterium pleistocenium sp. nov., a novel psychrotolerant, facultative anaerobe isolated from permafrost of the Fox Tunnel in Alaska.

A novel, psychrotolerant, facultative anaerobe, strain FTR1T, was isolated from Pleistocene ice from the permafrost tunnel in Fox, Alaska. Gram-positive, motile, rod-shaped cells were observed with sizes 0.6-0.7 x 0.9-1.5 microm. Growth occurred within the pH range 6.5-9.5 with optimum growth at pH 7.3-7.5. The temperature range for growth of the novel isolate was 0-28 degrees C and optimum growth occurred at 24 degrees C. The novel isolate does not require NaCl; growth was observed between 0 and 5 % NaCl with optimum growth at 0.5 % (w/v). The novel isolate was a catalase-negative chemoorganoheterotroph that used as substrates sugars and some products of proteolysis. The metabolic end products were acetate, ethanol and CO2. Strain FTR1T was sensitive to ampicillin, tetracycline, chloramphenicol, rifampicin, kanamycin and gentamicin. 16S rRNA gene sequence analysis showed 99.8 % similarity between strain FTR1T and Carnobacterium alterfunditum, but DNA-DNA hybridization between them demonstrated 39+/-1.5 % relatedness. On the basis of genotypic and phenotypic characteristics, it is proposed that strain FTR1T (=ATCC BAA-754T=JCM 12174T=CIP 108033T) be assigned to the novel species Carnobacterium pleistocenium sp. nov.

Desulfonatronum thiodismutans sp. nov., a novel alkaliphilic, sulfate-reducing bacterium capable of lithoautotrophic growth.

A novel alkaliphilic, sulfate-reducing bacterium, strain MLF1(T), was isolated from sediments of soda Mono Lake, California. Gram-negative vibrio-shaped cells were observed, which were 0.6-0.7x1.2-2.7 micro m in size, motile by a single polar flagellum and occurred singly, in pairs or as short spirilla. Growth was observed at 15-48 degrees C (optimum, 37 degrees C), >1-7 % NaCl, w/v (optimum, 3 %) and pH 8.0-10.0 (optimum, 9.5). The novel isolate is strictly alkaliphilic, requires a high concentration of carbonate in the growth medium and is obligately anaerobic and catalase-negative. As electron donors, strain MLF1(T) uses hydrogen, formate and ethanol. Sulfate, sulfite and thiosulfate (but not sulfur or nitrate) can be used as electron acceptors. The novel isolate is a lithoheterotroph and a facultative lithoautotroph that is able to grow on hydrogen without an organic source of carbon. Strain MLF1(T) is resistant to kanamycin and gentamicin, but sensitive to chloramphenicol and tetracycline. The DNA G+C content is 63.0 mol% (HPLC). DNA-DNA hybridization with the most closely related species, Desulfonatronum lacustre Z-7951(T), exhibited 51 % homology. Also, the genome size (1.6x10(9) Da) and T(m) value of the genomic DNA (71+/-2 degrees C) for strain MLF1(T) were significantly different from the genome size (2.1x10(9) Da) and T(m) value (63+/-2 degrees C) for Desulfonatronum lacustre Z-7951(T). On the basis of physiological and molecular properties, the isolate was considered to be a novel species of the genus Desulfonatronum, for which the name Desulfonatronum thiodismutans sp. nov. is proposed (the type strain is MLF1(T)=ATCC BAA-395(T)=DSM 14708(T)).

Spirochaeta americana sp. nov., a new haloalkaliphilic, obligately anaerobic spirochaete isolated from soda Mono Lake in California.

A novel, obligately anaerobic, mesophilic, haloalkaliphilic spirochaete, strain ASpG1(T), was isolated from sediments of the alkaline, hypersaline Mono Lake in California, USA. Cells of the Gram-negative strain were motile and spirochaete-shaped with sizes of 0.2-0.22 x 8-18 microm. Growth of the strain was observed between 10 and 44 degrees C (optimum 37 degrees C), in 2-12% (w/v) NaCl (optimum 3% NaCl) and between pH 8 and 10.5 (optimum pH 9.5). The novel strain was strictly alkaliphilic, required high concentrations of carbonates in the medium and was capable of utilizing D-glucose, fructose, maltose, sucrose, starch and D-mannitol. End products of glucose fermentation were H2, acetate, ethanol and formate. Strain ASpG(T) was resistant to kanamycin and rifampicin, but sensitive to gentamicin, tetracycline and chloramphenicol. The G + C content of its DNA was 58.5 mol%. DNA-DNA hybridization analysis of strain ASpG1(T) with its most closely related species, Spirochaeta alkalica Z-7491(T), revealed a hybridization value of only 48.7%. On the basis of its physiological and molecular properties, strain ASpG1(T) appears to represent a novel species of the genus Spirochaeta, for which the name Spirochaeta americana is proposed (type strain ASpG1(T) =ATCC BAA-392(T) = DSM 14872(T)).

Tindallia californiensis sp. nov., a new anaerobic, haloalkaliphilic, spore-forming acetogen isolated from Mono Lake in California.

A novel extremely haloalkaliphilic, strictly anaerobic, acetogenic bacterium strain APO was isolated from sediments of the athalassic, meromictic, alkaline Mono Lake in California. The Gram-positive, spore-forming, slightly curved rods with sizes 0.55-0.7x1.7-3.0 microm were motile by a single laterally attached flagellum. Strain APO was mesophilic (range 10-48 degrees C, optimum of 37 degrees C); halophilic (NaCl range 1-20% (w/v) with optimum of 3-5% (w/v), and alkaliphilic (pH range 8.0-10.5, optimum 9.5). The novel isolate required sodium ions in the medium. Strain APO was an organotroph with a fermentative type of metabolism and used the substrates peptone, bacto-tryptone, casamino acid, yeast extract, l-serine, l-lysine, l-histidine, l-arginine, and pyruvate. The new isolate performed the Stickland reaction with the following amino acid pairs: proline + alanine, glycine + alanine, and tryptophan + valine. The main end product of growth was acetate. High activity of CO dehydrogenase and hydrogenase indicated the presence of a homoacetogenic, non-cycling acetyl-CoA pathway. Strain APO was resistant to kanamycin but sensitive to chloramphenicol, tetracycline, and gentamycin. The G+C content of the genomic DNA was 44.4 mol% (by HPLC method). The sequence of the 16S rRNA gene of strain APO possessed 98.2% similarity with the sequence from Tindallia magadiensis Z-7934, but the DNA-DNA hybridization value between these organisms was only 55%. On the basis of these physiological and molecular properties, strain APO is proposed to be a novel species of the genus Tindallia with the name Tindallia californiensis sp. nov., (type strain APO = ATCC BAA-393 = DSM 14871).