2株石油降解菌生长和降解石油条件的优化

摘要

In order to increase the oil degradation rate of the two strains of petroleum degrading bacteria, DH -5 and DH - 9 isolated from the soil of the Shengli Oilfield, tests were done to screen out optimal composition of the medium for their growth and environmental conditions for petroleum degradation. It was found that Strain DH - 5 grew the best when the medium was composed of 1 g ? L-1 crude oil, 400 mg · L-1 N sources, 200 mg ? L-1 P sources, 20 mg ? L yeast extract, and 10 mg · L-1 arginine ( Arg) , which was the most effective among amino acid, and it performed the best when it was in an environment being 7. 0 in pH, 20 in salinity and 15 -30℃ in temperature. And under such conditions, oil degradation rate of DH -5 increased 11. 57 percent point. For best growth, DH -9 should be cultured in the medium composed of 1 g ? L-1 crude oil, 400 mg ? L-1 N sources, 100 mg · L-1 P sources, 20 mg ? L-1 yeast extract, and 10 mg ? L-1 aspartic acid (Asp) which was the most effective among amino acid, and it did the best in an environment being 7.5 in pH, 20 in salinity and 30℃ in temperature. Under such conditions, Strain DH -9 could degrade 64. 10% of crude oil, oil degradation rate increasing 20. 88 percent point. When the oil concentration reached 20 g ? L-1, DH -9 was 158% and 129% higher than DH -5 inbiomass and oil degradation rate, respectively. The findings indicate that Strain DH - 9 is significantly more tolerant to high concentrations of crude oil than Strain DH - 5, but Strain DH - 5 is more adaptable to low temperature than Strain DH -9. Besides, both of the two strains show strong adaptability to high salinity, which characterizes the local environment.%对2株石油降解菌DH -5和DH -9生长的最适培养基成分以及降解石油的最佳环境条件进行了筛选.结果表明,DH -5的最佳培养基成分为ρ(原油)1 g·L-1、ρ(氮源)400 mg·L-1、ρ(磷源)200 mg·L-1、ρ(酵母浸出液)20 mg·L-1,最有效利用的氨基酸为精氨酸,最适环境条件为pH 7.0、盐度20、温度15～ 30℃；DH -9的最佳培养基成分为ρ(原油)1 g·L-1 、ρ(氮源)400 mg·L-1、ρ(磷源)100 mg·L-1、ρ(酵母浸出液)20 mg· L-1,最有效利用的氨基酸为天冬氨酸,最适环境条件为pH7.5、盐度20、温度30℃.当ρ(原油)为20g·L-1时,DH -9的生物量和原油降解率分别是DH -5的2.58倍和2.29倍.研究表明,DH -9对高浓度原油的耐受性明显强于DH -5,而DH -5对低温的适应性优于DH -9,2个菌株对高盐度的适应性均较强.