Isolation of Halophiles from Qinghai Lake and Growth Characteristics of Dominant Strain QHL5

Thirty-five strains of halophiles were isolated from 20 water samples of Qinghai Lake,China by a high saline medium.In all strains tested,the proportion of the moderate halophile was 66.7%,as a dominate group,and the percentage of the slight halophile was 25.7.The nonhalophile plus halotolerant was however only 8.5%.The dominant strain QHL5 was a moderate halophile,which could grow in a salt concentration from 0.04 to 3.0 mol/L,and its optimal concentration was 0.3～0.9 mol/L.According to colonial morphology and growth characteristics,QHL5 was round or oval,4.0～6.0 mm,white,gram negative and opaque as a single cell.The optimum pH and cultural temperature were 7.5～8.0 and 35 ℃,respectively.Based on the physiological and biochemical characteristics of bacteria,and phylogenetic analysis using 16S rDNA sequence comparison,QHL5 was primarily identified as a Halomonas ventosae species of Holomonas genus,in Oceanospirillales order of Gammaproteobacteria class.The intracellular compatible solute of QHL5 was extracted with 80% ethanol,then the ectoine accumulated in cell was tested by a TLC method.