Geoalkalibacter ferrihydriticus gen. nov., sp. nov., the first alkaliphilic representative of the family Geobacteraceae, isolated from a soda lake

Investigation of iron reduction in bottom sediments of alkaline soda lakes resulted in the isolation of a new obligately anaerobic iron-reducing bacterium, strain Z-0531, from Lake Khadyn (Tuva Republic, Russia) sediment samples. The cells of strain Z-0531 are short (1.0-1.5 by 0.3-0.5 microm), motile, non-spore-forming, gram-negative rods. The isolate is an obligate alkaliphile, developing in the pH range of 7.8-10.0, with an optimum at pH 8.6. It does not require NaCl but grows at NaCl concentrations of 0-50 g/1l. It can oxidize acetate with such electron acceptors as amorphous Fe(llI) hydroxide (AFH), EDTA-Fe(III), anthraquinone-2,6-disulfonate (quinone), Mn(IV), and S(0). On media with EDTA-Fe(III), the isolate can oxidize, apart from acetate, ethanol, pyruvate, oxalate, arginine, tartrate, lactate, propionate, and serine. H2 is not utilized. The reduced products formed during growth with AFH are siderite or magnetite, depending on the growth conditions. The isolate is incapable of fermenting sugars, peptides, and amino acids. Yeast extract or vitamins are required as growth factors. The organism is capable of dinitrogen fixation and harbors the nifH gene. The DNA G+C content is 55.3 mol %. 16S rRNA analysis places strain Z-0531 into the family Geobacteraceae. Its closest relative (93% similarity) is Desulfuromonas palmitatis. Based on phenotypic distinctions and phylogenetic position, it is proposed that strain Z-0531 be assigned to the new genus and species Geoalkalibacter ferrihydriticus gen. nov., sp. nov.     

Clostridium alkalicellum sp. nov., an Obligately Alkaliphilic Cellulolytic Bacterium from a Soda Lake in the Baikal Region

Microbiology - The first anaerobic alkaliphilic cellulolytic microorganism has been isolated from the Verkhnee Beloe soda lake (Buryatiya, Russia) with pH 10.2 and a salt content of up to 24 g/l....     

<Emphasis Type="Italic">Natronincola ferrireducens</Emphasis> sp. nov., and <Emphasis Type="Italic">Natronincola peptidovorans</Emphasis> sp. nov., new anaerobic alkaliphilic peptolytic iron-reducing bacteria isolated from soda lakes

Two novel strains of obligately alkaliphilic (pH 7.5–10.2, optimum pH 8.4–8.8) anaerobic spore-forming rod-shaped bacteria, Z-0511 and Z-7031, were isolated from enrichment cultures obtained from the iron-reducing (Lake Khadyn, Tyva) and cellulolytic (Lake Verkhnee Beloe, Buryatia) bacterial communities, respectively. The organisms ferment peptides and do not ferment proteins and amino acids, with the exception of histidine and glutamate utilized by strain Z-0511. The major fermentation products were acetate and propionate for strain Z-0511 and formate and acetate for strain Z-7031, respectively. Carbohydrates and fermentable organic acids could not serve as substrates, except for pyruvate in the case of strain Z-7031. Nitrogen and sulfur compounds were not utilized as electron acceptors by the strains grown on medium with yeast extract. Strain Z-0511 utilized fumarate, crotonate, and EDTA-Fe(III) as electron acceptors. Anthraquinone-2,6-disulfonate (quinone) and Mn(IV) were utilized by both strains, as well as amorphous ferric hydroxide (AFH), which was reduced to iron sesquioxides and magnetite. The presence of AFH stimulated growth; it enhanced the yield of the fermentation products and changed the quantitative ratios of these products. According to a phylogenetic analysis of the 16S rRNA gene sequences and the phenotypic characteristics of the new strains, they were classified as new species of the genus Natronincola, Natronincola ferrireducens sp. nov. Z-0511^T (= VKM B-2402, = DSM 18346) and Natronincola peptidovorans sp. nov. Z-7031^T (= VKM B-2503, = DSM 18979).     

<Emphasis Type="Italic">Alkaliphilus peptidofermentans</Emphasis> sp. nov., a new alkaliphilic bacterial soda lake isolate capable of peptide fermentation and Fe(III) reduction

A novel strain, Z-7036, of anaerobic spore-forming bacteria was isolated from a cellulolytic consortium obtained from the bottom sediments of the low-mineralization soda lake Verkhnee Beloe (Buryatia). The cells of the new strain are short motile gram-positive rods, 1.1–3.0 × 0.25–0.4 μm. The organism is an aerotolerant anaerobe and obligate alkaliphile growing within the pH range of 7.5–9.7 with an optimum at pH 9.1. The strain is mesophilic and halotolerant and grows at NaCl concentrations from 0 to 50 g/l with an optimum at 20 g/l. Carbonates are required. The microorganism ferments peptone, yeast extract, trypticase, tryptone, Bacto Soytone, meat extract, Casamino acids, ornithine, arginine, threonine, and tryptophan. The strain hydrolyzes the bacterial preparations “Gaprin” and “Spirulina”. Acetate and formate are the major fermentation products. The strain reduces amorphous ferric hydroxide (AFH), EDTA-Fe(III), anthraquinone-2,6-disulfonate (quinone), S₂O ₃ ^2? , fumarate, and crotonate. Major fatty acids are C_16:0, C1_6:1ω7c, iso-C₁₇, iso-C₁₅, and iso-C_17:1. The DNA G+C content is 33.8 ± 0.5 mol %. According to the results of the 16S rRNA gene analysis, strain Z-7036 belongs to the genus Alkaliphilus within the cluster XI of low G+C gram-positive bacteria of the family Clostridiaceae. The novel strain is closely related to A. transvaalensis SAGM1^T and A. crotonatoxidans B11-2^T (93.3 and 93.9% 16S rRNA sequence identities, respectively). On the basis of the existing genotypic and phenotypic differences, we propose that strain Z-7036 should be classified as a novel species Alkaliphilus peptidofermentans sp. nov.     

Alkaliflexus imshenetskii gen. nov. sp. nov., a new alkaliphilic gliding carbohydrate-fermenting bacterium with propionate formation from a soda lake

Anaerobic saccharolytic bacteria thriving at high pH values were studied in a cellulose-degrading enrichment culture originating from the alkaline lake, Verkhneye Beloye (Central Asia). In situ hybridization of the enrichment culture with 16S rRNA-targeted probes revealed that abundant, long, thin, rod-shaped cells were related to Cytophaga. Bacteria of this type were isolated with cellobiose and five isolates were characterized. Isolates were thin, flexible, gliding rods. They formed a spherical cyst-like structure at one cell end during the late growth phase. The pH range for growth was 7.5–10.2, with an optimum around pH 8.5. Cultures produced a pinkish pigment tentatively identified as a carotenoid. Isolates did not degrade cellulose, indicating that they utilized soluble products formed by so far uncultured hydrolytic cellulose degraders. Besides cellobiose, the isolates utilized other carbohydrates, including xylose, maltose, xylan, starch, and pectin. The main organic fermentation products were propionate, acetate, and succinate. Oxygen, which was not used as electron acceptor, impaired growth. A representative isolate, strain Z-7010, with Marinilabilia salmonicolor as the closest relative, is described as a new genus and species, Alkaliflexus imshenetskii. This is the first cultivated alkaliphilic anaerobic member of the Cytophaga/Flavobacterium/Bacteroides phylum.Dedicated to Prof. Dr. Hans Günter Schlegel on the occasion of his 80th birthday.     

<Emphasis Type="Italic">Rhodobaca barguzinensis</Emphasis> sp. nov., a new alkaliphilic purple nonsulfur bacterium isolated from a soda lake of the Barguzin Valley (Buryat Republic,Eastern Siberia)

A novel strain, alga-05, of alkaliphilic purple nonsulfur bacteria was isolated from sediments of a small saline (60 g/l) soda lake near Lake Algin (Barguzin Valley, Buryat Republic, Russia). These bacteria contain bacteriochlorophyll a and carotenoids of the alternative spirilloxanthin group with predominating demethylspheroidenone. They are facultative anaerobes; their photosynthetic structures are of the vesicular type and arranged along the cell periphery. Growth of this strain is possible in a salinity range of 5–80 g/l NaCl, with an optimum at 20 g/l NaCl. Best growth occurred at 20–35°C. Analysis of the 16S rRNA gene sequences demonstrated that the studied isolate is closely related to the alkaliphilic purple nonsulfur bacterium Rhodobaca bogoriensis (99% similarity) isolated from soda lakes of the African Rift Zone. According to the results of DNA-DNA hybridization, strain alga-05 has a 52% similarity with the type species of the genus Rhodobaca. On the basis of the obtained genotypic data and some phenotypic properties (dwelling in a hypersaline soda lake of Siberia, moderate halophily, ability to grow at relatively low temperatures, etc.), the isolated strain of purple bacteria was described as a new species of the genus Rhodobaca, Rca. barguzinensis sp. nov.     

Amphibacillus fermentum sp. nov. and Amphibacillus tropicussp. nov., New Alkaliphilic,Facultatively Anaerobic,Saccharolytic Bacilli from Lake Magadi

New alkaliphilic, saccharolytic, rod-shaped, gram-positive bacteria resistant to heating and drying and phylogenetically affiliated to the Bacilluslineage were isolated under strictly anaerobic conditions from sediments of the alkaline and highly mineralized Lake Magadi. Strain Z-7792 forms endospores; in strain Z-7984, endospore formation was not revealed. The strains are capable of both anaerobic growth (at the expense of fermentation of glucose and certain mono- and disaccharides with the formation of formate, ethanol, and acetate) and aerobic growth. Among polysaccharides, the strains hydrolyze starch, glycogen, and xylan. Yeast extract or methionine are required for growth. The strains are strict alkaliphiles exhibiting obligate requirement for Na⁺and carbonate ions, but not for Cl^–ions. Growth occurs at a total mineralization as high as 3.3–3.6 M Na⁺, with an optimum at 1–1.7 M Na⁺. Strain Z-7792 is an obligate alkaliphile with a pH growth range of 8.5–11.5 and an optimum of 9.5–9.7. Strain Z-7984 grows in a pH range of 7.0–10.5 with an optimum at 8.0–9.5. Both strains are mesophiles having a growth optimum at 37–38°C. The G+C contents of the DNA of strains Z-7792 and Z-7984 are 39.2 and 41.5 mol %, respectively. These isolates of facultatively anaerobic, strictly alkaliphilic, Na⁺-dependent bacilli can be considered representatives of the ecological group adapted to life at drying-up shoals of soda lakes. Because of their independence of NaCl and lack of obligate dependence on sodium carbonates, the isolates are to be assigned to athalassophilic organisms. According to their physiological and phylogenetic characteristics, they taxonomically belong to group 1 of the species of bacilli with a low G+C content and occupy a position intermediate between the genera Amphibacillusand Gracilibacillus.The isolates are described as new species of Amphibacillus: A. fermentum(type strain, Z-7984^T) and A. tropicus(type strain, Z-7792^T).     

Ectothiorhodosinus mongolicum gen. nov., sp. nov., a New Purple Bacterium from a Soda Lake in Mongolia

A new nonmotile purple sulfur bacterium (strain M9) was isolated from the steppe soda lake Lake Dzun Uldziin Nur (pH 9.4; mineralization, 3.3%) situated in southeastern Mongolia. Individual cells appear as vibrios 0.3–0.5 × 0.7–1 m in size. The dividing cells often do not separate from each other, forming an almost closed ring. The internal photosynthetic membranes are represented by concentric lamellae lining the cell wall. Photosynthetic pigments are bacteriochlorophyll a and carotenoids of the spirilloxanthin series. The main carotenoid (>96%) is spirilloxanthin. Two typical light-harvesting complexes (LH1 and LH2) are present in the membranes in a 1 : 1 ratio. The bacterium is an anaerobe and facultative photoorganoheterotroph. Photolithoautotrophic growth on sulfide is scarce. Thiosulfate is utilized as an electron donor only in the presence of organic matter. Globules of elemental sulfur are formed as an intermediary product of sulfide and thiosulfate oxidation and are deposited outside the cells. The end product of oxidation is sulfate. In the presence of sulfide and carbonates, acetate, lactate, malate, pyruvate, propionate, succinate, and fumarate are used as additional sources of carbon in anoxygenic photosynthesis. Vitamins are not required. The bacterium is an alkaliphile, the pH optimum is at 8.3–9.1, the pH range is 7.6–10.1. The optimum NaCl concentration in the medium is 1 to 7%; the range is 0.5 to 0.9%. The optimum carbonate content in the medium is 2%; the range is 1 to 10%. The best growth occurs at 30–35°C. The DNA G+C content is 57.5 mol %. According to the results of analysis of the 16S rRNA gene sequences, the new isolate M9 belongs to the phylogenetic cluster containing representatives of the family Ectothiorhodospiraceae within the class Gammaproteobacteria. In this class, the new isolate forms a new branch, which occupies an intermediate position between the representatives of the genera Ectothiorhodospira and Thiorhodospira. Based on the phenotypic and genetic characteristics, the new purple sulfur bacterium was assigned to a new species of a new genus of the family Ectothiorhodospiraceae, Ectothiorhodosinus mongolicum gen. nov., sp. nov.     

Chimaereicella alkaliphila gen. nov., sp. nov., a Gram-negative alkaliphilic bacterium isolated from a nonsaline alkaline groundwater

A Gram-negative bacterium designated AC-74(T) was isolated from a highly alkaline groundwater environment (pH 11.4). This organism formed rod-shaped cells, is strictly aerobic, catalase and oxidase positive, tolerates up to 3.0% NaCl, has an optimum growth temperature of 30 degrees C, but no growth occurs at 10 or 40 degrees C, and an optimum pH value of 8.0, but no growth occurs at pH 7.0 or 11.3. The predominant fatty acids are iso-15:0, iso-17:1 omega9c and 16:1 omega7c and or iso-15:2OH. The G+C content of DNA was 43.5mol%. The phylogenetic analyses of the sequences of the 16s RNA genes indicated that strain AC-74(T) belongs to the family "Flexibacteriaceae" and is phylogenetically equidistant ( approximately 94.5%) from the majority of the species of the genus Algoriphagus and from the genus Hongiella. Based on the phylogenetic analyses and distinct phenotypic characteristics, we are of the opinion that strain AC-74(T), represents a new species of the novel genus for which we propose the name Chimaereicella alkaliphila gen. nov., sp. nov.     

Heliorestis daurensis, gen. nov. sp. nov., an alkaliphilic rod-to-coiled-shaped phototrophic heliobacterium from a Siberian soda lake

A novel alkaliphilic heliobacterium was isolated from microbial mats of a low-salt alkaline Siberian soda lake. Cells of the new organism were tightly coiled when grown in coculture with a rod-shaped bacterium, but grew as short filaments when finally obtained in pure culture. The new phototroph, designated strain BT-H1, produced bacteriochlorophyll g and a neurosporene-like pigment, and lacked internal photosynthetic membranes. Similar to other heliobacteria, strain BT-H1 grew photoheterotrophically on a limited range of organic compounds including acetate and pyruvate. Sulfide was oxidized to elemental sulfur and polysulfides under photoheterotrophic conditions; however, photoautotrophic growth was not observed. Cultures of strain BT-H1 were alkaliphilic, growing optimally at pH 9, and unlike other heliobacteria, they grew optimally at a temperature of 25 °C rather than at 40 °C or above. Analysis of the 16S rRNA gene sequence of the new organism showed that it groups within the heliobacterial clade. However, its branching order was phylogenetically basal to all previously investigated species of heliobacteria. The G+C content of the DNA of strain BT-H1 (44.9 mol%) was also quite distinct from that of other heliobacteria. This unique assemblage of properties implicates strain BT-H1 as a new genus and species of the heliobacteria, Heliorestis daurensis, named for its unusual morphology (“restis” is Latin for “rope”) and for the Daur Steppe in Russia in which these soda lakes are located. Received: 15 March 1999 / Accepted: 25 June 1999     

Natranaeroarchaeum sulfidigenes gen. nov., sp. nov., carbohydrate-utilizing sulfur-respiring haloarchaeon from hypersaline soda lakes,a member of a new family Natronoarchaeaceae fam. nov. in the order Halobacteriales

A pure culture of alkaliphilic haloarchaeon strain AArc-S^T capable of anaerobic growth by carbohydrate-dependent sulfur respiration was obtained from hypersaline lakes in southwestern Siberia. According to phylogenetic analysis, AArc-S^T formed a new genus level branch most related to the genus Natronoarchaeum in the order Halobacteriales. The strain is facultatively anaerobic with strictly respiratory metabolism growing either by anaerobic respiration with elemental sulfur and thiosulfate as the electron acceptors or by aerobic respiration at microoxic conditions. Thiosulfate is reduced partially to sulfide and sulfite. It is a first sulfur-reducing alkaliphilic haloarchaeon utilizing sugars, starch and glycerol as substrates for anaerobic growth. It is extremely halophilic (optimum at 3.5 M total Na⁺) and obligately alkaliphilic (optimum at pH 9.5). The dominant polar lipids include PG and PGP-Me with the archaeol (C₂₀-C₂₀) or extended archaeol (C₂₀-C₂₅) cores. The dominant respiratory lipoquinone is MK-8:8. On the basis of unique physiological properties and results of phylogenetic analysis, the soda lake isolate is suggested to be classified into a novel genus and species Natranaeroarchaeum sulfidigenes gen. nov., sp. nov. (=JCM 34033^T = UNIQEM U1000^T). Furthermore, on the bases of phylogenomic reconstruction, a new family Natronoarchaeaceae fam. nov. is proposed within the order Halobacteriales incorporating Natranaeroarchaeum and three related genera: Natronoarchaeum, Salinarchaeum and Halostella.     

Natronolimnobius baerhuensis gen. nov., sp. nov. and Natronolimnobius innermongolicus sp. nov., novel haloalkaliphilic archaea isolated from soda lakes in Inner Mongolia, China

Three novel isolates of haloalkaliphilic archaea, strains IHC-005^T, IHC-010, and N-1311^T, from soda lakes in Inner Mongolia, China, were characterized to elucidate their taxonomic positions. The three strains were aerobic, Gram-negative chemoorganotrophs growing optimally at 37–45°C, pH 9.0–9.5, and 15–20% NaCl. Cells of strains IHC-005^T/IHC-010 were motile rods, while those of strain N-1311^T were non-motile pleomorphic flats or cocci. The three strains contained diphytanyl and phytanyl-sesterterpanyl diether derivatives of phosphatidylglycerol and phosphatidylglycerophosphate methyl ester. No glycolipids were detected. On phylogenetic analysis of 16S rRNA gene sequences, they formed an independent cluster in the Natro group of the family Halobacteriaceae. Comparison of their morphological, physiological, and biochemical properties, DNA G+C content and 16S rRNA gene sequences, and DNA-DNA hybridization study support the view that strains IHC-005^T/IHC-010 and strain N-1311^T represent separate species. Therefore, we propose Natronolimnobius baerhuensis gen. nov., sp. nov. for strains IHC-005^T (=CGMCC 1.3597^T =JCM 12253^T)/IHC-010 (=CGMCC 1.3598=JCM 12254) and Natronolimnobius innermongolicus sp. nov. for N-1311^T (=CGMCC 1.2124^T =JCM 12255^T).     

Natronocalculus amylovorans gen. nov., sp. nov., and Natranaeroarchaeum aerophilus sp. nov., dominant culturable amylolytic natronoarchaea from hypersaline soda lakes in southwestern Siberia

Several pure cultures of alkaliphilic haloaloarchaea were enriched and isolated from hypersaline soda lakes in southwestern Siberia using amylopectin and fructans as substrates. Phylogenomic analysis placed the isolates into two distinct groups within the class Halobacteria. Four isolates forming group 1 were closely related to a recently described Natranaeroarchaeum sulfidigenes and the other three strains forming group 2 represent a novel genus-level phylogenetic lineage. All isolates are saccharolytic archaea growing with various starch-like alpha-glucans including soluble starch, amylopectin, dextrin, glycogen, pullulane and cyclodextrin. In addition, group 1 can use levan while group 2 – inulin (plant storage beta-fructans). Group 1 strains can also grow anaerobically with either glucose or maltose using elemental sulfur as the electron acceptor. Both groups are moderately alkaliphilic with a pH range for growth from 7.2 to 9.3 (optimum between 8.0–8.8) and low Mg-demanding extreme halophiles growing optimally at 4 M total Na⁺. The major respiratory menaquinone is MK-8:8 and the core biphytanyl lipids are dominated by archaeol (C₂₀-C₂₀) and a less abundant extended archaeol (C₂₀-C₂₅) with PG and PGP-Me as polar groups. The four isolates of group 1 are suggested to be classified into a new species as Natranaeroarchaeum aerophilus sp. nov. (type strain AArc-St1-1^T = JCM 32519^T). The three isolates of group 2 are proposed to form a new genus and species for which the name Natronocalculus amylovorans gen. nov., sp. nov. is suggested (type strain AArc-St2^T = JCM 32475^T).     

Halonatronum saccharophilum gen. nov. sp. nov.: A New Haloalkaliphilic Bacterium of the Order Haloanaerobiales from Lake Magadi

A new alkaliphilic and moderately halophilic chemoorganotrophic anaerobic bacterium (strain Z-7986), which is spore-forming, rod-shaped, and has a gram-negative cell wall pattern, was isolated from the coastal lagoon mud of the highly mineralized Lake Magadi (Kenya). The organism is an obligatorily carbonate- and sodium chloride-dependent motile peritrichously flagellated rod that grows within a 3–17% NaCl concentration range (with an optimum at 7–12% NaCl) and within a pH range of 7.7–10.3 (with an optimum at pH values of 8–8.5). It is a moderate thermophile with a broad temperature optimum at 36–55°C; maximum growth temperature is 60°C. The bacterium catabolizes glucose, fructose, sucrose, maltose, starch, glycogen, N-acetyl-D-glucosamine, and, to a slight degree, peptone and yeast extract. Its anabolism requires yeast extract or casamino acids. Glucose fermentation yields formate, acetate, ethanol, H₂, and CO₂. The bacterium is sulfide-tolerant and capable of the nonspecific reduction of S⁰ to H₂S. The G+C content of the DNA is 34.4 mol %. The analysis of the 16S rRNA sequence revealed that strain Z-7986 belongs to the order Haloanaerobiales and represents a new genus in the family Halobacteroidaceae. We suggest the name Halonatronum saccharophilum gen. nov. sp. nov. The type strain of this species is Z-7986^T (= DSM13868, = Uniqem*211).     

Natronobacillus azotifigens gen. nov., sp. nov., an anaerobic diazotrophic haloalkaliphile from soda-rich habitats

Gram-positive bacteria capable of nitrogen fixation were obtained in microoxic enrichments from soda soils in south-western Siberia, north-eastern Mongolia, and the Lybian desert (Egypt). The same organisms were obtained in anoxic enrichments with glucose from soda lake sediments in the Kulunda Steppe (Altai, Russia) using nitrogen-free alkaline medium of pH 10. The isolates were represented by thin motile rods forming terminal round endospores. They are strictly fermentative saccharolytic anaerobes but tolerate high oxygen concentrations, probably due to a high catalase activity. All of the strains are obligately alkaliphilic and highly salt-tolerant natronophiles (chloride-independent sodaphiles). Growth was possible within a pH range from 7.5 to 10.6, with an optimum at 9.5–10, and within a salt range from 0.2 to 4 M Na⁺, with an optimum at 0.5–1.5 M for the different strains. The nitrogenase activity in the whole cells also had an alkaline pH optimum but was much more sensitive to high salt concentrations compared to the growing cells. The isolates formed a compact genetic group with a high level of DNA similarity. Phylogenetic analysis based on 16S-rRNA gene sequences placed the isolates into Bacillus rRNA group 1 as a separate lineage with Amphibacillus tropicus as the nearest relative. In all isolates the key functional nitrogenase gene nifH was detected. A new genus and species, Natronobacillus azotifigens gen. nov., sp. nov., is proposed to accommodate the novel diazotrophic haloalkaliphiles. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. The GenBank accession numbers for the 16S rRNA gene of the novel strains are EU143681-EU143690 and EU850814-EU850816; for the nifH gene the accession numbers are EU542601, EU563380-EU563386 and EU850817-EU850819.     

Arsukibacterium ikkense gen. nov., sp. nov, a novel alkaliphilic, enzyme-producing gamma-Proteobacterium isolated from a cold and alkaline environment in Greenland

A novel aerobic, Gram-negative, non-pigmented bacterium, GCM72(T), was isolated from the alkaline, low-saline ikaite columns in the Ikka Fjord, SW Greenland. Strain GCM72(T) is a motile, non-pigmented, amylase- and protease-producing, oxidase-positive, and catalase-negative bacterium, showing optimal growth at pH 9.2-10.0, at 15 degrees C, and at 3% (w/v) NaCl. Major fatty acids were C(12:0) 3-OH (12.2+/-0.1%), C(16:00) (18.0+/-0.1%), C(18:1)omega7c (10.7+/-0.5%), and summed feature 3 comprising C(16:1)omega7c and/or iso-C(15:0) 2-OH (36.3+/-0.7%). Phylogenetic analysis based on 16S rRNA gene sequences showed that isolate GCM72(T) was most closely related to Rheinheimera baltica and Alishewanella fetalis of the gamma-Proteobacteria with a 93% sequence similarity to both. The G+C content of DNA isolated from GCM72(T) was 49.9mol% and DNA-DNA hybridization between GCM72T and R. baltica was 9.5%. Fatty acid analysis and G+C content supports a relationship primarily to R. baltica, but several different features, such as a negative catalase-response and optimal growth at low temperature and high pH, together with the large phylogenetic distance and low DNA similarity to its closest relatives, lead us to propose a new genus, Arsukibacterium, gen. nov., with the new species Arsukibacterium ikkense sp. nov. (type strain is GCM72(T)).     

Natronogracilivirga saccharolytica gen. nov., sp. nov. and Cyclonatronum proteinivorum gen. nov., sp. nov., haloalkaliphilic organotrophic bacteroidetes from hypersaline soda lakes forming a new family Cyclonatronaceae fam. nov. in the order Balneolales

Two heterotrophic bacteroidetes strains were isolated as satellites from autotrophic enrichments inoculated with samples from hypersaline soda lakes in southwestern Siberia. Strain Z-1702^T is an obligate anaerobic fermentative saccharolytic bacterium from an iron-reducing enrichment culture, while Ca. Cyclonatronum proteinivorum Omega^T is an obligate aerobic proteolytic microorganism from a cyanobacterial enrichment. Cells of isolated bacteria are characterized by highly variable morphology. Both strains are chloride-independent moderate salt-tolerant obligate alkaliphiles and mesophiles. Strain Z-1702^T ferments glucose, maltose, fructose, mannose, sorbose, galactose, cellobiose, N-acetyl-glucosamine and alpha-glucans, including starch, glycogen, dextrin, and pullulan. Strain Omega^T is strictly proteolytic utilizing a range of proteins and peptones. The main polar lipid fatty acid in both strains is iso-C_15:0, while other major components are various C₁₆ and C₁₇ isomers. According to pairwise sequence alignments using BLAST Gracilimonas was the nearest cultured relative to both strains (<90% of 16S rRNA gene sequence identity). Phylogenetic analysis placed strain Z-1702^T and strain Omega^T as two different genera in a deep-branching clade of the new family level within the order Balneolales with genus. Based on physiological characteristics and phylogenetic position of strain Z-1702^T it was proposed to represent a novel genus and species Natronogracilivirga saccharolityca gen. nov., sp. nov. (= DSMZ 109061^T =JCM 32930^T =VKM B 3262^T). Furthermore, phylogenetic and phenotypic parameters of N. saccharolityca and C. proteinivorum gen. nov., sp. nov., strain Omega^T (=JCM 31662^T, =UNIQEM U979^T), make it possible to include them into a new family with a proposed designation Cyclonatronaceae fam. nov..     

Natrarchaeobius chitinivorans gen. nov., sp. nov., and Natrarchaeobius halalkaliphilus sp. nov., alkaliphilic,chitin-utilizing haloarchaea from hypersaline alkaline lakes

Two groups of alkaliphilic haloarchaea from hypersaline alkaline lakes in Central Asia, Egypt and North America were enriched and isolated in pure culture using chitin as growth substrate. These cultures, termed AArcht, were divided into two groups: group 1 which includes eleven isolates from highly alkaline soda lakes and group 2 which contains a single isolate obtained from the alkaline hypersaline Searles Lake. The colonies of chitin-utilizing natronoarchaea were red-pigmented and surrounded by large zones of chitin hydrolysis. The free cells of both groups were mostly flat nonmotile rods, while the cells that attached to chitin or formed colonies on chitin plates were mostly coccoid. The isolates are obligate aerobic saccharolytic archaea utilizing chitin and chitosane (less actively) as the only sugar polymers as well as a few hexoses as their carbon and energy source. Both groups are extremely halophilic, growing optimally at 3.5–4 M total Na⁺, but they differ in their pH profiles: the main group 1 isolates are obligately alkaliphilic, while the single group 2 strain (AArcht-Sl^T) is alkalitolerant. The core archaeal lipids in both groups are dominated by C₂₀–C₂₀ and C₂₀–C₂₅ dialkyl glycerol ethers (DGE) in approximately equal proportion. Phylogenetic analysis indicated that the isolates form an independent genus-level lineage within the family Natrialbaceae with 3 species-level subgroups. The available genomes of the closest cultured relatives of the AArcht strains, belonging to the genera Natrialba and Halopiger, do not encode any chitinase-related genes. On the basis of their unique phenotypic properties and distinct phylogeny, we suggest that the obligate alkaliphilic AArcht isolates (group 1) with an identical phenotype are classified into a new genus and species Natrarchaeobius chitinivorans gen. nov., sp. nov., with strain AArcht4^T as the type strain (JCM 32476^T = UNIQEM U966^T), while the facultatively alkaliphilic strain AArcht-Sl^T (group 2) — as a new species Natrarchaeobius halalkaliphilus sp. nov. (JCM 32477^T = UNIQEM U969^T).     

Desulfosporomusa polytropa gen. nov., sp. nov., a novel sulfate-reducing bacterium from sediments of an oligotrophic lake

Five strains of sulfate-reducing bacteria were isolated from the highest positive dilutions of a most probable number (MPN) series supplemented with lactate and inoculated with sediments from the oligotrophic Lake Stechlin. The isolates were endospore-forming and were motile by means of laterally inserted flagella. They stained Gram-negative and contained b-type cytochromes. CO difference spectra indicated the presence of P582 as a sulfite reductase. Phylogenetic analyses of the 16S rDNA sequences revealed that the isolates were very closely affiliated with the genus Sporomusa. However, sulfate and amorphous Fe(OH)₃, but not sulfite, elemental sulfur, MnO₂, or nitrate were used as terminal electron acceptors. Homoacetogenic growth was found with H₂/CO₂ gas mixture, formate, methanol, ethanol, and methoxylated aromatic compounds. The strains grew autotrophically with H₂ plus CO₂ in the presence or absence of sulfate. Formate, butyrate, several alcohols, organic acids, carbohydrates, some amino acids, choline, and betaine were also utilized as substrates. The growth yield with lactate and sulfate as substrate was 7.0 g dry mass/mol lactate and thus two times higher than in sulfate-free fermenting cultures. All isolates were able to grow in a temperature range of 4–37°C. Physiologically and by the presence of a Gram-negative cell wall, the new isolates resemble known Desulfosporosinus species. However, phylogenetically they are affiliated with the Gram-negative genus Sporomusa belonging to the Selenomonas subgroup of the Firmicutes. Therefore, the new isolates reveal a new phylogenetic lineage of sulfate-reducing bacteria. A new genus and species, Desulfosporomusa polytropa gen. nov., sp. nov. is proposed.Dedicated to Prof. H. G. Schlegel on the occasion of his 80th birthday.     

Characterization of Halanaerobaculum tunisiense gen. nov., sp. nov., a new halophilic fermentative, strictly anaerobic bacterium isolated from a hypersaline lake in Tunisia

A new halophilic anaerobe was isolated from the hypersaline surface sediments of El-Djerid Chott, Tunisia. The isolate, designated as strain 6SANG, grew at NaCl concentrations ranging from 14 to 30%, with an optimum at 20–22%. Strain 6SANG was a non-spore-forming, non-motile, rod-shaped bacterium, appearing singly, in pairs, or occasionally as long chains (0.7–1 × 4–13 μm) and showed a Gram-negative-like cell wall pattern. It grew optimally at pH values between 7.2 and 7.4, but had a very broad pH range for growth (5.9–8.4). Optimum temperature for growth was 42°C (range 30–50°C). Strain 6SANG required yeast extract for growth on sugars. Glucose, sucrose, galactose, mannose, maltose, cellobiose, pyruvate, and starch were fermented. The end products from glucose fermentation were acetate, butyrate, lactate, H₂, and CO₂. The G + C ratio of the DNA was 34.3 mol%. Strain 6SANG exhibited 16S rRNA gene sequence similarity values of 91–92% with members of the genus Halobacteroides, H. halobius being its closest phylogenetic relative. Based on phenotypic and phylogenetic characteristics, we propose that this bacterium be classified as a novel species of a novel genus, Halanaerobaculum tunisiense gen. nov., sp. nov. The type strain is 6SANG^T (=DSM 19997^T = JCM 15060^T).