Production of medium chain fatty acids from antibiotic fermentation residuals pretreated by ionizing radiation: Elimination of antibiotic resistance genes.

[Display omitted] • MCFAs production from AFRs via two-stage anaerobic fermentation was performed. • Effect of radiation pretreatment on fate of ARGs and MCFA production was explored. • Radiation at 10–50 kGy decreased ARGs abundance by 0.6–21.1% at end of fermentation. • Radiation pretreatment of AFRs promoted the MCFA production. The propagation of antibiotic resistance genes (ARGs) restricts the application of antibiotic fermentation residues (AFRs). This study investigated medium chain fatty acids (MCFA) production from AFRs, focusing on the effect of ionizing radiation pretreatment on the fates of ARGs. The results indicated that ionizing radiation pretreatment not only stimulated the MCFA production, but also inhibited the proliferation of ARGs. Radiation at 10–50 kGy decreased ARGs abundances by 0.6–21.1% at the end of fermentation process. Mobile genetic elements (MGEs) exhibited higher resistance to ionizing radiation, radiation over 30 kGy was required to suppress the proliferation of MGEs. Radiation at 50 kGy achieved an adequate inhibition to MGEs, and the degradation efficiency was 17.8–74.5% for different kinds of MGEs. This work suggested that ionizing radiation pretreatment could be a good option to ensure the safer application of AFRs by eliminating the ARGs and preventing the horizontal gene transfer of ARGs. [ABSTRACT FROM AUTHOR]