Reduction of Typical Antibiotic Resistance Genes and Mobile Gene Elements in Sewage Sludge During Sludge Bioleaching with Acidithiobacillus ferrooxidans

Sewage sludge was considered a critical reservoir for the propagation of antibiotic resistance genes (ARGs) and its treatment and disposal were important for the environment and human health. This study investigated the efficiency of the bioleaching technology for reducing eight typical antibiotic resistance genes in municipal sewage sludge, which was an emerging environmentally friendly technology for sludge dewatering. The prevalence of forty ARGs subtypes (including two mobile gene elements, MEGs) and one 16SrRNA gene were concerned with high throughput quantitative polymerase chain reaction during sludge bioleaching and a total of sixteen ARGs subtypes (including two transposase genes) were presented in the sludge samples. These genes were significantly decreasing after bioleaching, namely, one sulfonamide resistance gene (sul2), five tetracycline resistance genes (tetA-02, tetB-01, tetG-01, tetO-01, tetX), four macrolide-lincosamide-streptogramin B (MLSB) resistance genes (ermF, mphA-01, mphA-02, lnuB-01), two β-lactam resistance genes (blaOXA1/blaOXA30, blaPSE), two aminoglycoside resistance genes [aac(6´)-Ib, strB] and two MEGs (tnpA-01, tnpA-03). This result indicated that the bioleaching technology could significantly reduce the ARGs abundance of sewage sludge and the maximum removal efficiency was sixty-eight percent (mphA-02) and other ARGs subtypes such as tetA-02, tetB-01, mphA-01 and blaOXA1/blaOXA30 were decreased over fifty percent. The characteristics of Acidithiobacillus ferrooxidans contributed to the sludge bioleaching and may influence the diversity and composition of bacterial community and consequentially result in the change of ARGs abundance.