Effects of Elevated Tetracycline Concentrations on Aerobic Composting of Human Feces: Composting Behavior and Microbial Community Succession

Abstract

In order to investigate the effect of antibiotics on composting behavior, enzymatic activity, and microbial community succession during the aerobic composting of human feces using sawdust as the bulk carrier, tetracycline (TC) was added to the composting system at four different concentrations (0, 100, 250, and 500 mg·kg-1). Microbial community succession was examined by high-throughput 16S rRNA gene sequencing. The results showed that the influence of TC on the physical and chemical properties of compost was related to its concentration. With the increase in TC concentration, the temperature increase during aerobic composting was inhibited, the water-soluble carbon (WSC) residue was increased, the germination index (GI) was decreased, and the dehydrogenase activity (DHA) was also hindered. Parameters, such as temperature, WSC, GI, and DHA, are widely accepted and representative indicators to evaluate compost maturity. Overall, when the concentration of TC was higher than 500 mg·kg-1, the aerobic composting process and the maturity of the final compost were inhibited. Furthermore, elevated TC caused significant changes in microbial community succession and reductions in community diversity and abundance. Therefore, interference in microbial community structures and a hindrance to biological activity are believed to be the main adverse effects of TC on the composting process and maturity of the composting products.