Fate of antibiotic resistance genes and its drivers during anaerobic co-digestion of food waste and sewage sludge based on microwave pretreatment

Sludge bio-drying: Effective to reduce both antibiotic resistance genes and mobile genetic elements

“…However, tetX was only found in Sphingobacterium and Bacteroides, and ermF in Bacteroides in previous study (McArthur et al, 2013). The significantly positive correlation with ARGs may be due to its functional connection with real antibiotic resistance bacteria, while these potential host bacteria may have the biggest chance of becoming the ARBs through HGT as suggested before (Zhang et al, 2016b). Network analysis further elucidated the significant correlation between evolution of ARGs and changes of bacterial community composition.…”

“…Bacteroidetes and BioCu could explain the evolution of ermF, tetX and sulII, while Firmicutes accounted for the patterns at the beginning in both piles, and the effects of MGEs on the evolution of tetG and tetQ should not be overlooked. To rank the variation of the contribution to the evolution of ARGs as a whole, partial RDA was further conducted by designating the explanatory variables and covariates as suggested previously (Zhang et al, 2016b). It was concluded that the bacterial community contributed the most to the ARG changes during sludge bio-drying, followed by MGEs and co-selection from heavy metals.…”

“…However, there was little available information on the fate of ARGs during sludge bio-drying. Because of the amounts of ARGs in sludge, there is a need to assess the potential of sludge bio-drying for ARGs reduction as what has been done for other sludge treatment technologies like aerobic digestion (Burch et al, 2013b), air-drying beds (Burch et al, 2013a), sludge composting (Zhang et al, 2016a) and anaerobic digestion (Zhang et al, 2016b), and efforts have been undertaken to optimize these sludge treatment technologies for reducing ARG quantities (Ma et al, 2011). Sludge bio-drying may provide a cost-effective way for removing ARGs from sewage sludge if they are found to reduce ARG concentrations effectively.…”

“…While high levels of heavy metals existed in sewage sludge, and thus effects of heavy metals on ARGs profiles during sludge treatment should be emphasized. Furthermore, changes of bacterial community were demonstrated as the main driver of the evolution of ARGs in various environments (Zhang et al, 2016a(Zhang et al, , 2016b. For instance, Su et al (2015) investigated the dynamics of ARGs and bacterial community using highthroughput PCR and sequencing during a lab-scale in-vessel sludge composting, results of mantel test and procrustes analysis indicated the significant correlation between ARGs contents and bacterial composition while partial RDA further confirmed the dominant contribution of bacterial communities to the dynamics of ARGs evolution compared to environmental factors and MGEs, and HGT via mobile genetic elements (MGEs) may also be facilitated with high density and diversity of microbial flora in sludge.…”

Occurrence of antibiotic resistance genes and mobile genetic elements in enterococci and genomic DNA during anaerobic digestion of pharmaceutical waste sludge with different pretreatments

“…During the AD, the total ARGs and MGEs relative abun- dance increased for the AD with MW and ozone pretreatment but decreased for the AD with TH pretreatment. In our previous Zhang et al, 2016) and present study, AD of sewage sludge with MW pretreatment increased the total absolute ARGs. Furthermore, the variations in individual ARGs were similar, that is, the gene copies of tetM, mefA/E, ermB and ermF increased after AD with MW pretreatment .…”