Effects of florfenicol on methane accumulation and changes in the structure of the prokaryotic community in a water–sediment system

Abstract

Florfenicol has been widely used in the veterinary and aquaculture to control bacterial diseases because of its high efficacy, quick effect, and low cost. The water–sediment system has become an important sink for florfenicol, and the anaerobic environment of lake sediments is favorable for methane (CH4) production. Although antibiotics may impact methanogenesis under anaerobic conditions, the influence of florfenicol on CH4 accumulation in anaerobic water–sediment system remains uncertain. This study evaluated how florfenicol affects CH4 accumulation and the structure of the prokaryotic community in a water–sediment system. Anaerobic systems with different florfenicol concentrations (0, 0.2, 1, 5 and 10 mg/L) were incubated and CH4 accumulation, pH, total organic carbon content, degradation ratio of florfenicol, and structure of the prokaryotic community were monitored. It was found that CH4 accumulation raised in low florfenicol (0.2 and 1 mg/L) systems during the growth period, while CH4 accumulation declined in high florfenicol (5 and 10 mg/L) systems. In the first 13 d, 83.67–99.30 % of florfenicol degraded in different treatments. The addition of florfenicol also influenced the structure of the prokaryotic community of the sediments. Proteobacteria and Chloroflexi were dominant at the phylum level. The dominant taxa at the order level gradually changed from Methanomicrobiales to Methanobacteriales, and finally to Methanosarcinales, indicating the dynamic transformation of methanogens in the reactor. This study reveals the effects of florfenicol on CH4 production under anaerobic conditions and provides a theoretical basis for further research on the underlying mechanisms. The findings also provide some basic data on the impact of new pollutants on the global carbon cycle and greenhouse gas emission.