Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
State Key Laboratory of Urban Water Resource and Environment, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China.
J Hazard Mater. 2024 Jan 15;462:132762. doi: 10.1016/j.jhazmat.2023.132762. Epub 2023 Oct 12.
Microbe-mediated anaerobic degradation is a practical method for remediation of the hazardous monoaromatic hydrocarbons (BTEX, including benzene, toluene, ethylbenzene and xylenes) under electron-deficient contaminated sites. However, how do the anaerobic functional microbes adapt to oxygen exposure and flexibly catabolize BTEX remain poorly understood. We investigated the switches of substrate spectrum and bacterial community upon oxygen perturbation in a nitrate-amended anaerobic toluene-degrading microbiota which was dominated by Aromatoleum species. DNA-stable isotope probing demonstrated that Aromatoleum species was involved in anaerobic mineralization of toluene. Metagenome-assembled genome of Aromatoleum species harbored both the nirBD-type genes for nitrate reduction to ammonium coupled with toluene oxidation and the additional meta-cleavage pathway for aerobic benzene catabolism. Once the anaerobic microbiota was fully exposed to oxygen and benzene, 1.05 ± 0.06% of Diaphorobacter species rapidly replaced Aromatoleum species and flourished to 96.72 ± 0.01%. Diaphorobacter sp. ZM was isolated, which was not only able to utilize benzene as the sole carbon source for aerobic growth and but also innovatively reduce nitrate to ammonium with citrate/lactate/glucose as the carbon source under anaerobic conditions. This study expands our understanding of the adaptive mechanism of microbiota for environmental redox disturbance and provides theoretical guidance for the bioremediation of BTEX-contaminated sites.
微生物介导的厌氧降解是在电子匮乏污染场地修复危险单环芳烃（BTEX，包括苯、甲苯、乙苯和二甲苯）的实用方法。然而，厌氧功能微生物如何适应氧气暴露并灵活地代谢 BTEX 仍知之甚少。我们研究了在硝酸盐添加的厌氧甲苯降解微生物群中，氧气扰动时底物谱和细菌群落的变化，该微生物群主要由 Aromatoleum 物种组成。DNA 稳定同位素探测表明，Aromatoleum 物种参与了甲苯的厌氧矿化。Aromatoleum 物种的宏基因组组装基因组同时包含用于将硝酸盐还原为铵并与甲苯氧化偶联的nirBD 型基因，以及用于好氧苯代谢的额外的 meta 裂解途径。一旦厌氧微生物群完全暴露于氧气和苯中，Diaphorobacter 种的 1.05±0.06%迅速取代 Aromatoleum 种并繁盛到 96.72±0.01%。分离到了 Diaphorobacter sp. ZM，它不仅能够利用苯作为唯一碳源进行好氧生长，而且还能够在厌氧条件下利用柠檬酸盐/乳酸盐/葡萄糖作为碳源创新地将硝酸盐还原为铵。本研究扩展了我们对微生物群适应环境氧化还原干扰的机制的理解，并为 BTEX 污染场地的生物修复提供了理论指导。
