Studies On Isolation And Polyphasic Taxonomy Of Halphiles

The highly promising microbial resources, halophiles have been paid extensive attention in recent years under novel research. We are far from the separation of halophilic microorganisms till now. Therefore, the isolation of more unknown halophiles including extremely halophiles archaeon and moderately halophile bacterium is a necessary prerequisite and key for development of microganism resources. There are many high-salt environmental natural resources in China including large areas of saline soil and many salt lakes in Xingjiang, Inner Mongolia, Shandong, Qinghai and Gansu. It can provid unique condition for study on isolation and systematic taxonomy of high-salt environmental microorganisms.Microorganisms were isolated from samples taken from Qingdao and Hexi in Gansu province. Study on systematic taxonomy of isolated halophiles had been done using polyphasic technology including morphological and cultural characteristic obserbations, physiological and chemical tests, analyses of chemtaxonomy and G+C content, DNA-DNA homology and 16S rRNA sequences.Cells of CM5 isolated from crude salt samples taken from Qingdao, were cocci and Gram-negative, which requires at least 10% NaCl for growth with 18% was optimum concentration. Gelatin was not liquefied and catalase reaction was positive. The strain was susceptible to rifampicin and bacitracin. Main polar lipids were phosphatidylglycerol, phosphatidylglycerol methylphosphate and sulfated diglycosyl diether. Cells of CM1 were rod and Gram-positive, which grew between 2.5% to 20% NaCl (w/v) with optima at 12% NaCl. The optima temperature for growth was 37°C. The optimal pH for growth was 9.0. It was positive for catalase reaction and nitrate reduction. Major fatty acids were anteiso-C_15:0, anteiso-C_17:0 and iso-C_16:0. The major isoprenoid quinones were MK-7(H₂) and MK-6(H₂). We identified CM5 and CM1 as two new species of genus Halococcus as Halococcus qingdaonensis sp. nov and genus Bacillus as Bacillus qingdaonensis sp. nov respectively. The research papers about these two new species have also been published in the reputed journals like International Journal of Systematic and Evolutionary Microbiology.Isolation and identification of preliminary work have been done for the samples taken from Yanchi salt-mining area of Hexi corridor of Gansu. Strains of moderately halophilic bacteria and extreme halophilic archaea were isolated from these samples. It can be concluded by 16S rDNA sequences that moderately halophilic bacteria are novel species of genus Marinococcus and genus Lentibacillus. Further study for proving this novel observation is still in progress. At the same time, halophilic archaea strains, broken in distilled water and haloalkaliphilic archaea strains, grown in medium of pH9.5 were isolated from these samples and sequencing of the 16S rDNA sequences are being conducted taking other polyphasic taxonomy identification.