Species Identification And Taxonomic Study Of Microorganism Isolated From Qiangtang And Mohe Permafrost Of China

In the study of the diversity of microbes in the underground environment at permafrost regions, qiangtang of qinghai-tibet plateau and mohe plateau in China, using dilution-plate method, two strains were isolated, designated Z4T and F4T. In order to confirm the specific position of strains Z4 and F4 in microbial taxonomy, this study focuses on a series of identification and taxonomic study. These develop their genetic relationship with known microbes, and provide theoretical basis for development, utilization, control and transform of relative resources.Cells of the strain Z4T are Gram-positive, aerobic, rod-shaped, non-motile, and 0.3-0.5 μm wide and 0.8-2.0 μm long. Colonies are white-colored, circular with entire margin and 0.5-1.0 mm in diameter on TSB agar plates at 25℃ after 3-day incubation. Growth occurs with 0-6.0% NaCl, at 20-42℃ and at pH 6.0-11.0. Optimal growth is observed with 3% NaCl, at 25℃ and at pH 8. Cells are positive for: hydrolysis of starch, gelatine, aesculin and 4-nitrophenyl-β-D-galactopyranoside; H2S production, urea, and D-glucose, mannose and maltose utilization etc. The 16S rRNA gene sequence analysis indicated that it was closely related to Jonesia quinghaiensis DSM 15701T and Jonesia denitrificans DSM 20603T, with pairwise sequence similarities of 95.1% and 94.1%, respectively.Cells of the strain F4T are 0.9-1.5 μm long×0.3-0.7 μm wide. Colonies on R2A agar are 0.6.0-1.0 mm in size, circular, entire, smooth and white-coloured at 37℃ for 3 days. The temperature range for growth is 20-42℃ (optimum 37℃), pH 5.0-9.0 (optimum 8.0),0-6.0% (w/v) NaCl (optimum 0.5%). The strain is positive for:catalase and oxidase activities; hydrolysis of gelatine, aesculin, casein and Tween 80. Cells are sensitive to ciprofloxacin, gentamicin, chloramphenicol, amikacin, kanamycin, neomycin. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain F4T was a member of the family Hyphomicrobiaceae and was most closely related to members of the genera Pelagibacterium, Vasilyevaea, Devosia with 93.8-96.2% sequence similarities.