Anaerobic digestion (AD) is an important
biological resource
recovery
process, where microorganisms play key roles for material transformation.
There has been some knowledge about the prokaryotic community and
antibiotic resistance genes (ARGs) in AD, but there has been very
limited knowledge of phages. In this study, samples from a full-scale
AD plant were collected over 13 months, sequenced, and analyzed for
viral and prokaryotic metagenomes. Totally, 3015 viral operational
taxonomic units (vOTUs) were detected, mostly assigned to Caudoviricetes. The phage community had faster temporal
variation than the prokaryotic community. Warm seasons harbored a
higher abundance of both temperate phages and broad host-range phages.
Seven ARGs of 6 subtypes were carried by 20 vOTUs, a representative ermT gene was synthesized and expressed, and the resistance
activity in the host was examined, confirming the real activity of
virus-carried ARGs in the AD process. Some of the ARGs were horizontally
transferred between the phage and prokaryotic genomes. However, phage
infection was not found to contribute to ARG transfer. This study
provided an insight into the ecological patterns of the phage community,
confirmed the antibiotic resistance activity of virus-carried ARGs,
evaluated the contribution of phages on the ARG prevalence, and laid
the foundation for the control strategies of the community and antibiotic
resistance in the AD process.