Effect of immobilized anthraquinone-2-sulfonate on antibiotic resistance genes and microbial community in biofilms of anaerobic reactors

Abstract

Quinone compounds could significantly accelerate anaerobic biotransformation of refractory pollutants. However, the effect of quinone compounds application on the propagation of antibiotic resistance genes (ARGs) in the bio-treatment of these pollutants-containing wastewater is not available. In this study, the catalytic performance of anthraquinone-2-sulfonate immobilized on polyurethane foam (AQS-PUF), changes of ARGs, mobile gene elements (MGEs) and microbial community structure attached on AQS-PUF and PUF in the up-flow anaerobic bioreactors were investigated. The results showed that AQS-PUF could significantly accelerate the decolorization of azo dye RR X–3B. Meanwhile, metagenomics analysis showed that the total absolute abundance of ARGs increased in the presence of the immobilized AQS. Among ARGs, the number of the efflux pump-encoding ARGs in the biofilm of AQS-PUF accounted for 35.7% of the total ARGs, which was slightly higher than that of PUF (32.1%) due to the presence of the immobilized AQS. The relative abundances of ARGs conferring resistance to MLS (macrolide, lincosamide and streptogramin), tetracycline and sulfonamide, which were deeply concerned, reduced 10%, 21.7% and 7.3% in the presence of the immobilized AQS, respectively. Moreover, the immobilized AQS resulted in the decreased relative abundance of plasmids, transposons and class I integrons. Among the detected 31 ARG subtypes located in MGEs, the relative abundances of only lnuF, msrE and mphD in the biofilm of AQS-PUF were over 2-fold higher compared with those in the biofilm of PUF. However, the three ARGs and their host Gammaproteobacteria was not dominant in microbial community. The relative abundances of more ARGs including MLS (lnuB and EreA), tetracycline (tetH) resistance genes located in MGEs decreased, which was attributed to the decreased relative abundance of their hosts. These studies showed that the addition of the immobilized AQS (around 0.25 mM) had a beneficial effect on reducing the spread of ARGs during dyeing wastewater bio-treatment.