Humic analog AQDS can act as a selective inhibitor to enable anoxygenic photosynthetic bacteria to outcompete sulfate‐reducing bacteria under microaerobic conditions

Abstract

BACKGROUND The anoxygenic photosynthetic bacteria (APB) process is considered the most promising candidate for cost‐effective wastewater treatment and resource recovery. One major problem in the APB process with sulfate‐containing wastewater is the overgrowth of sulfate‐reducing bacteria. In this study, the humic analog anthraquinone‐2,6‐disulfonate (AQDS) was used to selectively inhibit sulfate‐reducing bacteria (SRB) in an SRB and APB coculture. RESULTS The addition of 1.0 mmol L−1 AQDS to the SRB and APB coculture resulted in significant decreases in the amount of SRB and the sulfide concentration, whereas the number of APB increased from 3.7 × 103 to 3.1 × 108 CFU mL−1. A high concentration of AQDS negatively affected the growth of both SRB and APB but more strongly inhibited the growth of SRB. The inhibition of SRB by AQDS relies on an electron donor and is enhanced by illumination. AQDS treatment at 1.0 mmol L−1 induced significant membrane depolarization and superoxide production in SRB cells but not in APB cells, and this may be responsible for the selective inhibition of SRB in the coculture. CONCLUSION At appropriate concentrations, AQDS can decrease the concentration of sulfide and induce oxidative stress for SRB, effectively allowing APB to out‐compete SRB under microaerobic conditions. © 2015 Society of Chemical Industry