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Silanimonas lenta gen. nov., sp. nov., a slightly thermophilic and alkaliphilic gammaproteobacterium isolated from a hot spring

Lee, Eun Mi, Jeon, Che Ok, Choi, Inpyo, Chang, Kyu-Seob, Kim, Chang-Jin

International Journal of Systematic and Evolutionary Microbiology 2005; 55(1):385 · https://doi.org/10.1099/ijs.0.63328-0

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Summary auto-generated

Researchers isolated a moderately thermophilic bacterium, designated strain 25-4T, from a hot spring at Baekdoo Mountain in Korea. The organism is a Gram-negative, motile rod belonging to the Gammaproteobacteria family Xanthomonadaceae. Based on 16S rRNA gene sequence analysis showing 92.9-94.4% similarity to related genera, along with distinctive physiological and biochemical characteristics, the authors established a new genus and species: Silanimonas lenta. The bacterium grows optimally at 47°C and pH 9.0, with a temperature range of 25-53°C and pH range of 6.0-10.0. It is strictly aerobic, catalase- and oxidase-positive, and contains Q-8 as its major quinone with iso-branched fatty acids as predominant cellular components. The genomic DNA G+C content of 50.7 mol% is notably lower than related thermophilic gammaproteobacteria, particularly distinguishing it from the closely related Thermomonas haemolytica. The strain hydrolyzes starch, casein, gelatin, and other proteins, and produces various enzymes including alkaline phosphatase and lipases. This characterization adds to the growing diversity of slightly thermophilic proteobacteria isolated from hot spring environments.

Key findings

  • Silanimonas lenta is a novel genus and species of slightly thermophilic, alkaliphilic gammaproteobacterium with optimal growth at 47°C and pH 9.0
  • The organism has a distinctively low genomic DNA G+C content of 50.7 mol%, significantly lower than related thermophilic genera, facilitating differentiation from closely related species
  • 16S rRNA phylogenetic analysis indicates strain 25-4T forms a unique lineage within family Xanthomonadaceae with 92.9-94.4% sequence similarity to nearest relatives
  • The bacterium contains three unknown polar lipids and characteristic iso-branched fatty acids (C15:0 iso and C16:0 iso as major components) that distinguish it from related taxa

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Abstract

A moderately thermophilic aerobic bacterium, strain 25-4T, was isolated from a hot spring at Baekdoo Mountain in Korea. The cells were Gram-negative, motile rods each having a polar flagellum. Analysis of the 16S rRNA gene sequence indicated that the strain represented a new lineage within the family Xanthomonadaceae of the Gammaproteobacteria, being most closely related to the genera Thermomonas, Xanthomonas, Luteimonas, Pseudoxanthomonas, Stenotrophomonas and Xylella and having 16S rRNA gene sequence similarities to the most related species of the genera of between 92·9 and 94·4 %. The strain contained Q-8 as the major isoprenoid quinone and had a fatty acid profile with predominant iso-branched fatty acids. Growth occurred at pH 6·010, with an optimum at pH 9·0, and at 2553 °C, with an optimum at 47 °C. The G+C content of the genomic DNA was 50·7 mol%. On the basis of phylogenetic analyses and its phenotypic characteristics, strain 25-4T belongs to a new genus, Silanimonas gen. nov., within the Gammaproteobacteria. The sole species of this genus is Silanimonas lenta sp. nov. (type strain, 25-4T=DSM 16282T=KCTC 12236T).