摘要

    沼气消化液是抗生素抗性基因（ARG）的库，如果ARGs的宿主微生物被雾化，则可能对人类和动物都构成很高的健康风险。本研究的目的是研究沼气消化液中气溶胶负载的ARGs的多样性和相对丰度特征，并探讨沼气消化液中ARGs的变化是否直接影响气溶胶负载的ARGs的分散。这项研究首次报道，在实验室规模的动态排放容器实验中，在沼气消化液中检测到的42种ARG亚型中，有28种可以通过气溶胶扩散而散布到大气中。气溶胶中ARGs的相对丰度或多样性与沼气消化物中的相对丰度或多样性不同，并且在沼气消化物和气溶胶中ARGs的相对丰度之间没有显着相关性。优势ARGs是沼气消化物中的四环素抗性基因和气溶胶中的β-内酰胺抗性基因。沼气消化液的储存过程降低了沼气消化物中目标ARG的总相对丰度，在储存30天后降低了0.35拷贝/ 16S rRNA，但增加了一些ARG亚型的丰度，包括tetM，tetX，tetQ，tetS，ermF和sul2。在沼气消化液中发现了高度关注的ARG，包括NDM-1，mcr-1和万古霉素抗性基因（包括vanA，vanB，vanRA和vanSA），在气溶胶中也检测到NDM-1和vanB。这些结果表明在沼气消化液存储过程中ARGs扩散的潜在风险。需要进一步研究沼气消化液中ARG的分散性，以阐明其排放机理并制定缓解措施。

    Biogas digestate is a reservoir of antibiotic resistance genes (ARGs) and could pose a high health risk to both human and animals if the host microorganisms of ARGs become aerosolized. The purpose of this study was to investigate the diversity and relative abundance characteristics of aerosol-loaded ARGs from biogas digestate during storage, and to explore whether the change of ARGs in biogas digestate directly affect the dispersion of aerosol-loaded ARGs. This study reported for the first time that 28 of 42 ARG subtypes detected in the biogas digestate could be dispersed to the atmosphere via aerosol dispersion in a lab-scale dynamic emission vessels experiment. The relative abundance or diversity of ARGs in aerosols were different from that in biogas digestate, and no significant correlation were observed between the relative abundance of ARGs in biogas digestate and aerosols. The dominant ARGs were tetracycline resistance genes in biogas digestate and β-lactam resistance genes in aerosols. The process of biogas digestate storage reduced the total relative abundance of targeted ARGs in biogas digestate, decreased by 0.35 copies/16S rRNA after 30 days of storage, but increased the abundance of some ARG subtypes, including tetM, tetX, tetQ, tetS, ermF and sul2. High-concerned ARGs, including NDM-1, mcr-1 and vancomycin resistance genes (including vanA, vanB, vanRA and vanSA), were found in biogas digestate, and NDM-1 and vanB were also detected in aerosols. These results indicated a potential risk of ARGs dispersion during biogas digestate storage. Further research on the dispersion of ARGs from biogas digestate is required to elucidate the emission mechanism and develop mitigation measures.

    https://www.sciencedirect.com/science/article/abs/pii/S0048969720376397