Enrichment, domestication, degradation, adaptive mechanism, and nicosulfuron bioremediation of bacteria consortium YM2
Yufeng Xiao, Meiqi Dong, Xian Wu, Shuang Liang, Ranhong Li, Hongyu Pan, Hao Zhang
Abstract
Nicosulfuron (NSR), a sulfonylurea herbicide, can easily enter water bodies, affecting aquatic life and human safety. Here, bacteria consortium YM2 was enriched and domesticated from the active sludge of a pesticide plant for the bioremediation of NSR wastewater. The response surface methodology data revealed that under optimal incubation conditions: 9.41 g L–1 maltodextrin, 21.37 g L–1 yeast extract, and 12.45 g L–1 NaCl, YM2 bacteria consortium degraded 97.49% of NSR within 4 d. The optimal degradation conditions were temperature 30°C, pH 6.0, inoculum 1%, and initial NSR concentration 20 mg L–1), The degradation system was tolerant to heavy metal ions such as Cd2+, Pb2+, Ni2+, and Zn2+ and mainly occurred through the bacterial extracellular enzymes (92.17%). Mechanistically, during the degradation process, reactive oxygen species, oxidative stress, cell membrane permeability, cell surface hydrophobicity, and apoptosis rate first increased and then decreased. Also, the expression of biofilm formation-related genes luxS, waaE, spo0A, and wza varied with time and concentration. NSR wastewater and soil were degraded to 1.92 mg L–1 and 2.72 mg L–1, respectively. In a simulated wastewater treatment unit (hydraulic retention time 12 h), YM2 degraded 84.55% of NSR after 10 d. This study provides a theoretical basis for the microbial remediation of NSR.