Metagenomic analysis reveals microbial metabolic potentials alterations under antibiotic stress during sludge anaerobic digestion

The presence of antibiotics in sludge is considered to have a detrimental effect on methane production and microbial community. However, the underlying mechanism of how antibiotic impact the metabolic potentials is still unclear. This study investigated the long-term effects of antibiotics on different stages of sludge anaerobic digestion and on the metabolic potentials of key functional microorganism, revealed the response mechanism of dominant microbiome on antibiotic stress through metagenomic sequencing and binning strategy. Experimental results demonstrated that the abundance of many functional genes associated with glycolysis, protein hydrolysis and acidification increased by 3 %–200 % under the antibiotics stress. While functional genes related to acetate and acetyl-coA conversion were reduced. Besides, the major methanogenic metabolic pathways had also been altered under antibiotic stress, from acetoclastic methanogenesis to methanogenesis of methylamine. The metabolic potentials of ten typical metagenome-assembled genomes (MAGs) associated with hydrolysis, acidogenesis and methanogenesis were also investigated through the metagenomic binning strategy. The dominant MAGs under antibiotic stress contained abundant functional genes associated with EPS biosynthesis, secondary metabolite biosynthesis and bacterial chemotaxis, which may contribute to their dominance. This study shed light on complex metabolic potentials of microorganisms under the antibiotic stress, and provide novel insights into the underlying mechanism of antibiotic inhibition on anaerobic digestion.