Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada.
SiREM, 130 Stone Road West, Guelph, Ontario N1G 3Z2, Canada.
Environ Sci Technol. 2021 Jun 15;55(12):7970-7980. doi: 10.1021/acs.est.1c00508. Epub 2021 May 27.
Reliance on bioremediation to remove benzene from anoxic environments has proven risky for decades but for unknown reasons. Research has revealed a strong link between anaerobic benzene biodegradation and the enrichment of highly specific microbes, including in the family and the deltaproteobacterial Candidate Sva0485 clade. Using aquifer materials from Canadian Forces Base Borden, we compared five bioremediation approaches in batch microcosms. Under conditions simulating natural attenuation or sulfate biostimulation, benzene was not degraded after 1-2 years of incubation and no enrichment of known benzene-degrading microbes occurred. In contrast, nitrate-amended microcosms reported benzene biodegradation coincident with significant growth of spp., along with a functional gene presumed to catalyze anaerobic benzene carboxylation (). Inoculation with 2.5% of a methanogenic benzene-degrading consortium containing Sva0485 ( ORM2) resulted in benzene biodegradation in the presence of sulfate or under methanogenic conditions. The presence of other hydrocarbon co-contaminants decreased the rates of benzene degradation by a factor of 2 to 4. Tracking the abundance of the gene and 16S rRNA genes specific for benzene-degrading and Sva0485 is recommended to monitor benzene bioremediation in anoxic groundwater systems to further uncover growth-rate-limiting conditions for these two intriguing phylotypes.
几十年来，人们一直依赖生物修复来去除缺氧环境中的苯，但由于未知原因，这种方法一直存在风险。研究表明，厌氧苯生物降解与高度特定微生物的富集之间存在很强的联系，包括 和 δ 变形菌门的 Candidate Sva0485 分支。本研究使用来自加拿大博登空军基地的含水层材料，在批量微宇宙中比较了五种生物修复方法。在模拟自然衰减或硫酸盐生物刺激的条件下，经过 1-2 年的孵育，苯没有降解，也没有出现已知的苯降解微生物的富集。相比之下，添加硝酸盐的微宇宙报告称，苯的生物降解与 spp. 的显著生长同时发生，同时还存在一个被认为催化厌氧苯羧化的功能基因（）。接种含有 Sva0485 的 2.5%产甲烷苯降解菌混合物（ORM2）可在硫酸盐存在或产甲烷条件下实现苯的生物降解。其他碳氢化合物共污染物的存在使苯降解的速率降低了 2 到 4 倍。建议跟踪基因和特定于苯降解和 Sva0485 的 16S rRNA 基因的丰度，以监测缺氧地下水系统中的苯生物修复，从而进一步揭示这两种有趣的生物型的生长速率限制条件。
