Temperature impacts fate of antibiotic resistance genes during vermicomposting of domestic excess activated sludge

Effect of temperature on antibiotic resistance genes (ARGs) during vermicomposting of domestic excess sludge remains poorly understood. Vermicomposting experiment with excess sludge was conducted at three different temperatures (15 degrees C, 20 degrees C, and 25 degrees C) to investigate the fate of ARGs, bacterial community and their relationship in the process. The vermicomposting at 25 degrees C did not significantly attenuate the targeted ARGs relative to that at 15 degrees C and 20 degrees C. The dynamics of qnrA, qnrS, and tetM genes during vermicomposting at 15 degrees C and 20 degrees C followed the first-order kinetic model. Temperature remarkably impacted bacterial diversity of the final products with the lowest Shannon index at 25 degrees C. The presence of the genus (Aeromonas and Chitinophagaceae) at 25 degrees C may contribute to the rebound of the genes (qnrA, qnrS and tetM). The study indicates that 20 degrees C is a suitable vermicomposting temperature to simultaneously reach the highest removal efficiency of the ARGs and the good biostability of the final product.