Volatile Fatty Acid Recovery and Antibiotic Degradation from Erythromycin Fermentation Residual by Combined Thermal Pretreatment and Anaerobic Fermentation

Abstract

High resistance of erythromycin has been the key factor restricting the disposal of erythromycin fermentation residues (EFR). Considering the high sensitivity of erythromycin to acidic conditions, anaerobic fermentation may be a good approach for EFR treatment, through which pH decreases along with the volatile fatty acids (VFA) accumulation. This study firstly explored the EFR treatment by combined low-temperature thermal pretreatment and anaerobic fermentation. Results showed that thermal pretreatment and anaerobic fermentation exhibited a good synergistic effect on erythromycin removal, and erythromycin removal rate of 60% was obtained, which was 33.3% and 71.4% higher than erythromycin removal by sole thermal pretreatment and anaerobic fermentation. Thermal pretreatment induced the increased VFA production by 22.3%, and highest VFA concentration of 5325.4 mg/L was obtained. Microbial analysis shows that thermal pretreatment stimulated erythromycin degradation and VFA production by increasing the microbial diversity and enriching the functional enzymes involved in acetate-producing pathways.

Keywords: erythromycin fermentation residues, Anaerobic fermentation, thermal pretreatment, volatile fatty acids, microbial community