一株耐盐柴油降解菌的分离鉴定及其降解性能

从某油田附近受石油污染土壤中分离出一株以柴油为惟一碳源的耐盐菌株LS1。通过对菌株的生理生化特性、菌体的形态观察及16S rDNA基因序列分析鉴定菌株LS1为假单胞菌属(pseudomonas)。该菌株可耐受的最高盐度(NaCl)和柴油浓度分别为6%~8%和12 000 mg/L。菌株生长的适宜pH和温度条件分别为6.0~8.0和28~36℃。在盐度为6%、pH为7.0、温度为32℃、菌种投加量为10%的条件下,初始浓度为3 000 mg/L的柴油经6 d降解后,去除率可达78.3%,加入适量外加碳源葡萄糖和蔗糖,可使降解率分别提高至92%和90%左右。菌株LS1的耐盐机理可能是通过在细胞内积累甜菜碱以调节菌株细胞内外渗透压平衡。投加甜菜碱可提高耐盐菌LS1在高盐环境下对柴油的降解效率。

Isolation,identification and degradation characteristics of a salt-tolerant diesel-degrading bacterium strain

A salt-tolerant diesel-degrading bacterium LS1,which could utilize diesel as sole carbon source,was isolated from oil-contaminated soil near some oil field.On the basis of morphology,biochemical and physiological characteristics and 16S rDNA sequence analysis,strain LS1 was identified as pseudomonas sp.Strain LS1 could tolerate 6%~8% of NaCl and 12 000 mg/L of diesel.The suitable ranges of pH and temperature for strain LS1 growth are 6.0~8.0 and 28~36℃,respectively.Under the conditions of salinity of 6%,pH of 7.0,temperature of 32℃,strains dosage of 10%(v/v),the degradation rate of diesel with initial concentration of 3000 mg/L is up to 78.3%.Exotic glucose or sucrose enhances the degradation rate from 78.3% to 92% and 90%,respectively.The salt-tolerance mechanism of strain LS1 is possible due to the accumulation of betaine in the cell,which regulate the osmotic pressure balance of cell.Exotic betaine could enhance diesel degrading efficiency by strain LS1 under the presence of high salinity.