Department of Microbiology, Key Lab of Environmental Microbiology for Agriculture, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Sci Total Environ. 2020 Dec 1;746:140992. doi: 10.1016/j.scitotenv.2020.140992. Epub 2020 Jul 18.
The environmental fate of the recalcitrant organic chlorine insecticide lindane and its removal from contaminated soils are still of great concern. However, the key factors influencing microbial removal of lindane from paddy soils with intermittent flooding and draining remain largely unknown. Here, we conducted laboratory experiments to investigated lindane biodegradation in different layers of typical acidic paddy soils under different water managements and bioremediation strategies, together with the changes of functional bacterial consortium, key genes and metabolic pathways. It was found that under flooded conditions, lindane spiking significantly stimulated the growth of some bacterial genera with potential anaerobic catabolic functions in both top- (0-20 cm depth) and subsoil (20-40 cm depth), leading to the shortest half-life of lindane with 7.6-9.0 d in the topsoil. In contrary, lindane spiking dramatically stimulated the growth of bacterial members with aerobic catabolic functions under drained conditions, exhibiting half-lives of lindane with 85-131 d and 18-23 d in the top- and subsoil, respectively. Overall, biostimulation coupled with flooding management would be the better combination for increased lindane bioremediation. Functional genes involved in lindane degradation and retrieved from metagenomic data further supported the anaerobic and aerobic biodegradation of lindane under flooded and drained conditions, respectively. Moreover, the integrated network analysis suggested water management and organic matter were the primary factors shaped the assembly of functional bacteria in lindane degradation, among which Clostridium and Rhodanobacter were the key anaerobic and aerobic functional genera, respectively. Taken together, our study provides a comprehensive understanding of lindane biodegradation in distinct layers of acidic paddy soils that were combinedly affected by different water managements and bioremediation strategies.
林丹作为一种难降解的有机氯杀虫剂，其在环境中的归趋及其从污染土壤中的去除仍然是人们关注的焦点。然而，间歇性淹水和排水条件下影响微生物从稻田土壤中去除林丹的关键因素在很大程度上仍不清楚。在这里，我们通过实验室实验研究了不同水分管理和生物修复策略下典型酸性稻田土壤不同层中林丹的生物降解情况，以及功能细菌群落、关键基因和代谢途径的变化。结果发现，在淹水条件下，林丹的添加显著刺激了具有潜在厌氧代谢功能的一些细菌属在表土（0-20cm 深度）和底土（20-40cm 深度）中的生长，导致林丹的半衰期最短，表土中的半衰期为 7.6-9.0d。相反，在排水条件下，林丹的添加显著刺激了具有好氧代谢功能的细菌成员的生长，表土和底土中的林丹半衰期分别为 85-131d 和 18-23d。总的来说，生物刺激与淹水管理相结合将是提高林丹生物修复的更好组合。从宏基因组数据中获得的参与林丹降解的功能基因进一步支持了林丹在淹水和排水条件下的厌氧和好氧生物降解。此外，综合网络分析表明，水分管理和有机质是塑造林丹降解功能细菌组装的主要因素，其中梭菌属和红杆菌属分别是关键的厌氧和好氧功能属。总之，本研究提供了对不同水分管理和生物修复策略联合作用下酸性稻田土壤中林丹生物降解的全面认识。
