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Response and mechanisms of the performance and fate of antibiotic resistance genes to nano-magnetite during anaerobic digestion of swine manure

Zhang, Junya, Wang, Ziyue, Lu, Tiedong, Liu, Jibao, Wang, Yawei, Shen, Peihong, Wei, Yuansong
Journal of hazardous materials 2019 v.366 pp. 192-201
anaerobic digestion, antibiotic resistance genes, electron transfer, methane production, microbial communities, pig manure
Swine manure is an important reservoir of environmental antibiotic resistance genes (ARGs), and anaerobic digestion (AD) is a commonly used method for swine manure treatment. In this study, the optimized dosage of nano-magnetite to enhance methane production was figured out, the changes of the fate of ARGs response to nano-magnetite were investigated, and the microbial mechanisms were deciphered through the microbial community analysis and key functional genes quantification. Results showed that nano-magnetite could improve the methane production by maximum 6.0%, the maximum daily methane production could be increased by 47.8%, and the AD time could be shortened by above 20.0% at the addition of 75 mmol. The improved performance could be associated with the enhancement of direct interspecies electron transfer (DIET) and the inhibition release due to the formation of Fe-S precipitation not the nutrition elements role of nano-magnetite, and nano-magnetite did not significantly influence the dynamics of microbial community. Nano-magnetite could enhance the methanogenesis instead of the acetogenesis reflected by the functional genes analysis, and the limited effects of nano-magnetite on the fate of ARGs could be associated with its limited influence on the microbial community which determined the fate of ARGs during AD of swine manure.