[Interference of Dead Cell DNA on the Analysis of Antibiotic Resistance Genes and Microbial Community in Anaerobic Digestion Sludge].

Abstract

To investigate the potential interference of dead bacteria DNA on the analysis of antibiotic resistance genes (ARGs) and microbial communities in anaerobic digestion sludge, three different types of anaerobic digestion sludge were treated with propidium monoazide (PMA) in this study, and the results of subsequent ARGs and microbial community analysis with the interference of dead cell DNA blocked by PMA was compared to that without PMA treatment. It was found that after PMA treatment, the absolute abundance of the ARGs in the anaerobic digestion sludge from self-anaerobic digestion system of excess sludge and from high solid sludge anaerobic digestion system decreased by 41%-86%, and 74%-98%, respectively. ARGs abundance in the sludge from the anaerobic digestion system with sludge hydrolyzate as a substrate and anaerobic granular sludge as inoculum after 15 days of digestion considerably decreased with PMA treatment. However, its ARGs abundance still declined by up to 34%. PMA treatment influenced the analysis of microbial community of the three types of anaerobic digestion sludge to different degrees, in which the influence was the highest on the community structure analysis of the sludge from high solid anaerobic digestion system. The results of the correlation analysis between the ARGs abundance and the microbial community composition were completely different in the case with PMA treatment and without PMA treatment. This study proved the potential interference of dead cell DNA on the analysis of ARGs and microbial community in anaerobic digestion sludge. PMA pretreatment could achieve a more accurate analysis of the microbial community and ARGs characteristics in anaerobic digestion sludge.