Waste activated sludge (WAS) from wastewater treatment plants is an important reservoir of antibiotic resistance genes (ARGs). The fate of ARGs in this process was not revealed previously. The present study applied metagenomic approach to examine the occurrence and fate of ARGs in thermophilic alkaline fermentation followed by mesophilic anaerobic digestion (TM), by comparison with mesophilic alkaline fermentation followed by mesophilic anaerobic digestion (MM) and one-stage mesophilic anaerobic digestion (M) process. The removal efficiency of two-stage anaerobic digestion (AD) to total ARGs is higher than that of one-stage AD. The hydrogen and methane production stages of two-stage AD processes have dissimilar impact on the fate of ARGs. Macrolide, lincosamide, and streptogramin (MLS) resistance genes were enriched, especially in the hydrogen production reactors of TM and MM processes. Statistical analysis of metagenomic profiles analysis suggested that bacA may be the differential ARG subtype of two-stage AD process. ARG-like sequences encoding antibiotic efflux pump, antibiotic inactivation and antibiotic target alteration mechanisms were identified as the dominant ARGs resistance mechanisms in all samples. Procrustes analysis showed that microbial community composition structured the resistome. Co-occurrence patterns between ARGs and microbial phylogeny revealed that 26 bacterial species might be potential hosts of 94 ARG subtypes.

废水处理厂产生的废活性污泥（WAS）是重要的抗生素抗性基因（ARGs）库。ARGs在此过程中的命运先前并未透露。本研究采用宏基因组学方法来研究嗜热碱性发酵，中温厌氧消化（TM），嗜温碱性发酵，中温厌氧消化（MM）和一阶段中温厌氧消化（M）的嗜热碱性发酵中ARGs的发生和去向）过程。两阶段厌氧消化（AD）对总ARG的去除效率高于一阶段AD。两阶段反渗透工艺的氢气和甲烷生产阶段对ARG的命运有不同的影响。大环内酯，林可酰胺和链霉菌素（MLS）耐药基因丰富，特别是在TM和MM工艺的制氢反应器中。宏基因组谱分析的统计分析表明bac A可能是两阶段AD过程的差分ARG亚型。编码抗生素外排泵，抗生素失活和抗生素靶点改变机制的类ARG序列被确定为所有样品中主要的ARGs耐药机制。前驱物分析表明，微生物群落组成构成了抵抗组。ARG和微生物系统发育之间的共现模式表明26种细菌可能是94种ARG亚型的潜在宿主。