Proteinivorax tanatarense gen. nov., sp. nov., an anaerobic, haloalkaliphilic, proteolytic bacterium isolated from a decaying algal bloom, and proposal of Proteinivoraceae fam. nov.

Two strains of a novel anaerobic, protein- and nucleoside-utilizing bacterium, Z-910^T and Z-810, were isolated. The strains were spore-forming, mainly nonmotile rods, exhibiting positive Gram reaction with Gram-positive cell wall structure. The strains were mesophilic and haloalkaliphilic. Cultures used proteins and proteinaceous substrates as carbon, nitrogen, and energy sources. Both strains used also ribonucleosides, cellobiose, pyruvate, and glycerol. Ribose and nucleobases did not support growth. The fermentation products from all utilized substrates were identical but varied in content and included straight and branched acids, as well as hydrogen and ammonia. When grown on tryptone, strain Z-910^T was able to reduce fumarate, dimethyl sulfoxide, thiosulfate, and elemental sulfur. Neither nitrate nor sulfate was reduced. The DNA G + C content of strain Z-910^T was 32.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence similarity revealed that strains Z-910^T and Z-810 represented a new branch within the order Clostridiales, with 90.2 % similarity to the nearest genus with a validly published name Anaerobranca gottschalkii DSM 13577^T. According to their physiological, chemotaxonomic, and phylogenetic properties, strains Z-910^T and Z-810 represented a new genus and novel species, for which the name Proteinivorax tanatarense gen. nov., sp. nov. was proposed. Phylogenetic analysis showed that the genera Proteinivorax gen. nov. and Anaerobranca formed a separate cluster within the order Clostridiales. The family Proteinivoraceae fam. nov. comprising the genera Proteinivorax gen. nov. and Anaerobranca was therefore proposed within the order Clostridiales of the phylum Firmicutes with Proteinivorax as a type genus of the new family.     

Methanogenesis in the Lake Elton saline aquatic system

Extremophiles - Cultivation and molecular approaches were used to study methanogenesis in saline aquatic system of the Lake Elton (southern Russia), the largest hypersaline lake in Europe. The...     

<Emphasis Type="Italic">Halomonas mongoliensis</Emphasis> sp. nov. and <Emphasis Type="Italic">Halomonas kenyensis</Emphasis> sp. nov., new haloalkaliphilic denitrifiers capable of N<Subscript>2</Subscript>O reduction,isolated from soda lakes

In the course of the search for N₂O-utilizing microorganisms, two novel strains of haloalkaliphilic denitrifying bacteria, Z-7009 and AIR-2, were isolated from soda lakes of Mongolia and Kenya. These microorganisms are true alkaliphiles and grow in the pH ranges of 8.0–10.5 and 7.5–10.6, respectively. They are facultative anaerobes with an oxidative type of metabolism, able to utilize a wide range of organic substrates and reduce nitrate, nitrous oxide, and, to a lesser extent, nitrite to gaseous nitrogen. They can oxidize sulfide in the presence of acetate as the carbon source and nitrous oxide (strain Z-7009) or nitrate (strain AIR-2) as the electron acceptor. The strains require Na⁺ ions. They grow at 0.16–2.2 M Na⁺ (Z-7009) and 0.04–2.2 M Na⁺ (AIR-2) in the medium. The G+C contents of the DNA of strains Z-7009 and AIR-2 are 67.9 and 65.5 mol %, respectively. According to the results of 16S rRNA gene sequencing and DNA-DNA hybridization, as well as on the basis of physiological properties, the strains were classified as new species of the genus Halomonas: Halomonas mongoliensis, with the type strain Z-7009^T (=DSM 17332, =VKM B2353), and Halomonas kenyensis, with the type strain AIR-2^T (=DSM 17331, =VKM B2354).     

Laboratory Simulation of “Proteolytic Bacterium–Cyanobacterium” Interaction in Alkaliphilic Microbial Community

Paleontological Journal - The work continues the series of long-term studies of the microbial diversity of soda lakes and concerns the problem of anaerobic decomposition of proteins. The physiology...     

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....     

Analysis of the bacterial community developing in the course of <Emphasis Type="Italic">Sphagnum</Emphasis> moss decomposition

Slow degradation of organic matter in acidic Sphagnum peat bogs suggests a limited activity of organotrophic microorganisms. Monitoring of the Sphagnum debris decomposition in a laboratory simulation experiment showed that this process was accompanied by a shift in the water color to brownish due to accumulation of humic substances and by the development of a specific bacterial community with a density of 2.4 × 10⁷ cells ml^?1. About half of these organisms are metabolically active and detectable with rRNA-specific oligonucleotide probes. Molecular identification of the components of this microbial community showed the numerical dominance of bacteria affiliated with the phyla Alphaproteobacteria, Actinobacteria, and Planctomycetes. The population sizes of the Firmicutes and Bacteroidetes, which are believed to be the main agents of bacterially-mediated decomposition in eutrophic wetlands, were low. The numbers of planctomycetes increased at the final stage of Sphagnum decomposition. The representative isolates of the Alphaproteobacteria were able to utilize galacturonic acid, the only low-molecular-weight organic compound detected in the water samples; the representatives of the Planctomycetes were able to decompose some heteropolysaccharides, which points to the possible functional role of these groups of microorganisms in the community under study. Thus, the composition of the bacterial community responsible for Sphagnum decomposition in acidic and low-mineral oligotrophic conditions seems to be fundamentally different from that of the bacterial community which decomposes plant debris in eutrophic ecosystems at neutral pH.     

Halomonas mongoliensis sp. nov. and Halomonas kenyensis sp. nov., new haloalkaliphilic denitrifiers capable of reducing N2O, isolated from soda lakes

In the course of the search for N2O-utilizing microorganisms, two novel strains of haloalkaliphilic denitrifying bacteria, Z-7009 and AIR-2, were isolated from soda lakes of Mongolia and Kenya. These microorganisms are true alkaliphiles and grow in the pH ranges of 8.0-10.5 and 7.5-10.6, respectively. They are facultative anaerobes with an oxidative type of metabolism, able to utilize a wide range of organic substrates and reduce nitrate, nitrous oxide, and, to a lesser extent, nitrite to gaseous nitrogen. They can oxidize sulfide in the presence of acetate as the carbon source and nitrous oxide (strain Z-7009) or nitrate (strain AIR-2) as the electron acceptor. The strains require Na+ ions. They grow at medium mineralization levels of 0.16-2.2 M Na+ (Z-7009) and 0.04-2.2 M Na+ (AIR-2). The G+C contents of the DNA of strains Z-7009 and AIR-2 are 67.9 and 65.5 mol %, respectively. According to the results of 16S rRNA gene sequencing and DNA-DNA hybridization, as well as on the basis of physiological properties, the strains were classified as new species of the genus Halomonas: Halomonas mongoliensis, with the type strain Z-7009T (=DSM 17332, =VKM B2353), and Halomonas kenyensis, with the type strain AIR-2T (=DSM 17331, =VKM B2354).     

Clostridium alkalicellum sp. nov., an obligately alkaliphilic cellulolytic bacterium from a soda lake in the Baikal region

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. Five strains were characterized. Strain Z-7026 was chosen as the type strain. The cells of the isolate are gram-positive spore-forming rods. A mucous external capsule is produced. The microorganism is obligately alkaliphilic, growing in a pH range of 8.0-10.2, with an optimum at pH 9.0. Sodium ions and, in carbonate-buffered media, sodium chloride are obligately required. The microorganism is slightly halophilic; it grows at 0.017-0.4 M Na+ with an optimum at 0.15-0.3 M Na+. The metabolism is fermentative and strictly anaerobic. Cellulose, cellobiose, and xylan can be used as growth substrates. Plant and algal debris can be fermented. Lactate, ethanol, acetate, hydrogen, and traces of formate are produced during cellulose or cellobiose fermentation. Yeast extract or vitamins are required for anabolic purposes. The microorganism fixes dinitrogen and is nitrogenase-positive. It is tolerant to up to 48 mM Na2S. Growth is not inhibited by kanamycin or neomycin. Chloramphenicol, streptomycin, penicillin, ampicillin, ampiox, bacillin, novobiocin, and bacitracin suppress growth. The DNA G+C content is 29.9 mol %. According to the nucleotide sequence of its 16S rRNA gene, strain Z-7026 is phylogenetically close to the neutrophilic cellulolytic bacteria Clostridium thermocellum (95.5%), C. aldrichii (94.9%), and Acetivibrio cellulolyticus (94.8%). It is proposed as a new species: Clostridium alkalicellum sp. nov.     

Anoxybacillus kamchatkensis sp. nov., a novel thermophilic facultative aerobic bacterium with a broad pH optimum from the Geyser valley, Kamchatka

A facultative aerobic, moderately thermophilic, spore forming bacterium, strain JW/VK-KG4 was isolated from an enrichment culture obtained from the Geyser valley, a geothermally heated environment located in the Kamchatka peninsula (Far East region of Russia). The cells were rod shaped, motile, peritrichous flagellated stained Gram positive and had a Gram positive type cell wall. Aerobically, the strain utilized a range of carbohydrates including glucose, fructose, trehalose, proteinuous substrates, and pectin as well. Anaerobically, only carbohydrates are utilized. When growing on carbohydrates, the strain required yeast extract and vitamin B₁₂. Anaerobically, glucose was fermented to lactate as main product and acetate, formate, ethanol as minor products. Aerobically, even in well-aerated cultures (agitated at 500 rpm), glucose oxidation was incomplete and lactate and acetate were found in culture supernatants as by-products. Optimal growth of the isolate was observed at pH^{25 C} 6.8–8.5 and 60°C. The doubling times on glucose at optimal growth conditions were 34 min (aerobically) and 40 min (anaerobically). The G+C content was 42.3 mol% as determined by T_m assay. Sequence analysis of the 16S rRNA gene indicated an affiliation of strain JW/VK-KG4 with Anoxybacillus species. Based on its morphology, physiology, phylogenetic relationship and its low DNA-DNA homology with validly published species of Anoxybacillus, it is proposed that strain JW/VK-KG4 represents a new species in the genus Anoxybacillus as A. kamchatkensis sp. nov. The type strain for the novel species is JW/VK-KG4^T (=DSM 14988, =ATCC BAA-549). The GenBank accession number for the 16S rDNA sequence is AF510985.