The impact mechanism of chlortetracycline on different stages of anaerobic fermentation of organic wastes

Abstract

Chlortetracycline (CTC) is widely used in animal husbandry, which is directly discharged into the environment through feces due to incomplete absorption by animals, resulting in the continuous accumulation of chlortetracycline in the soil and water environment. In order to explore the effect of CTC addition on the microbial population and richness during the three stages of the anaerobic fermentation (AF), firstly, the samples of control group (CK), hydrolysis + CTC (HC)，acidification + CTC (AC) and methanogenesis + CTC (MC) group were set, respectively. Then, the 100 mL of 4.0 g/L CTC solution was added into the AF reactor of the HC, AC and MC on the 8th, 16th and 24th day and sampled with high-throughput sequencing analysis of microbial flora. The results showed that no matter the CTC added in any fermentation stages, it would have impacts on the microbial activity, cumulative gas production, cellulose crystal structure and functional group absorption peak intensity during the AF. In particular, it had a significant inhibitory effect on the biological activities of the SBR1031, Hydrogenispora and Ruminiclostridium_1 in the acidification stage and the Anaerolinea in the methanogenesis stage, which showed that CTC mainly inhibited the growth and reproduction of microorganisms in the acidification stage to inhibit the subsequent advancement of the entire fermentation. Consequently, the CTC addition had a significant inhibitory effect on microorganisms in different stages, which illustrated the pretreatment of organic waste contained CTC was necessity before the AF treatment.