柴油降解菌的筛选、菌群构建及其对柴油和十五烷的降解机理

Screening and community construction of diesel oil degrading bacteria and their degradation mechanism of diesel oil and pentadecane

针对柴油污染土壤生物修复技术效率低的问题,通过构建高效降解菌群修复柴油污染的土壤,采用组合优化和正交实验构建最佳组合与接种比例的菌群,并研究其柴油降解特性。结果表明,通过筛选、鉴定并命名的4株柴油降解菌为Bacillus sp. VOC18-L1、 Enterococcus faecalis-L2、 Lysinibacillus-L3、 Rhodococcus equi-L4;当4株菌接种比例为3∶1∶3∶4,pH=7.0,30℃,转速150 r·min^-1时,柴油降解的效果最佳,14 d对7.0 mL·L^-1的柴油降解率达到89.0%。通过气相色谱质谱联用仪(GC-MS)检测柴油降解产物,发现该混合菌株能将柴油中的烷烃降解为短链烷烃,最终转化为小分子物质。同时利用KEGG数据库获得代谢丰度图并初步预测每种菌的功能,根据微生物多样性测试结果,进一步证明了混合菌对柴油完全降解的效果优于单种菌种。通过人工构建的微生物菌群可以有效地应用于柴油污染土壤的修复。

In view of the current low efficiency of bioremediation technology for diesel oil-contaminated soil, a highly efficient flora was constructed to remediate the polluted soil. A combinatorial optimization and orthogonal design were used to construct the flora with the optimal combination and inoculation ratios, and their degradation characteristics of the diesel oil were also studied. The results showed that four diesel degrading bacteria were screened, identified and named as Bacillus sp. VOC18-L1、 Enterococcus faecalis-L2、Lysinibacillus-L3、Rhodococcus equi-L4. The optimal degradation efficiency was obtained at their inoculation ratios of 3∶1∶3∶4, pH=7.0, 30 ℃ and the rotational speed of 150 r·min^-1. After 14 days of incubation, the degradation efficiency of 7.0 mL·L^-1 diesel oil reached 89.0%. The degradation products of diesel oil were detected using GC-MS, which indicated that these mixed strains could first degrade the long-chain alkanes in diesel oil into short-chain alkanes and finally converted them into some small molecular organics. The metabolic abundance maps obtained from KEGG database were used to predict the functions of each strain. According to the results of microbial diversity test, it was further proven that the mixed flora was superior to pure strain in the complete degradation of diesel oil. The artificially optimized and constructed microbial flora could effectively degrade diesel oil in contaminated soil.