Effects of nano-zerovalent iron on antibiotic resistance genes during the anaerobic digestion of cattle manure. (October 2019) - Ma, Jiyue
Highlights: nZVI enhanced the methane yield during anaerobic digestion of cattle manure. Antibiotic resistance genes (ARGs) effectively removed by 160 mg/L nZVI. Mobile genetic elements were the main drivers of the changes in ARGs. Addition of 160 mg/L nZVI reduced abundances of Tn916/1545 and Acinetobacter . Abstract: This study investigated the effects of adding nano-zerovalent iron (nZVI) at three concentrations (0, 80, and 160 mg/L) on the methane yield and the fate of antibiotic resistance genes (ARGs) during the anaerobic digestion (AD) of cattle manure. The addition of nZVI effectively enhanced the methane yield, where it significantly increased by 6.56% with 80 mg/L nZVI and by 6.43% with 160 mg/L nZVI. The reductions in the abundances of ARGs and Tn916/1545 were accelerated by adding 160 mg/L nZVI after AD. Microbial community analysis showed that nZVI mainly increased the abundances of bacteria with roles in hydrolysis and acidogenesis, whereas it reduced the abundance of Acinetobacter . Redundancy analysis indicated that the changes in mobile genetic elements made the greatest contribution to the fate of ARGs. The results suggest that 160 mg/L nZVI is a suitable additive for reducing the risks due to ARGs in AD.