Review of biodegradation of sulfonamide antibiotics influenced by dissolved organic matter and iron oxides

Large amounts of sulfonamide antibiotics (SAs) are easily accumulated in the environment due to their difficult degradation, high doses of usage and not easily metabolized by the human body, causing adverse effects on the ecological environment. Biodegradation with low cost and high efficiency are widely used in antibiotic pollution treatment. Additionally, SAs biodegradation is often influenced by dissolved organic matter (DOM) and iron minerals. DOM is widely distributed in the soil and water and DOM is an important complexing agent, adsorbent, or redox agent for environmental pollutants, which enhances the mobility of SAs and facilitates biodegradation. There are four main ways of interaction between iron minerals and microorganisms: direct contact, cellular appendages, chelation, electronic shuttle effect. DOM acts as an electron shuttle between iron oxides and iron-reducing bacteria, which affect the degradation of SAs. Hence, the electron transfer happened among Fe(Ⅱ)/Fe(Ⅲ) from iron minerals and DOM and SAs and microorganisms. Additionally, microorganisms can obtain the energy for growth through the dissimilatory reduction of Fe(Ⅲ) and further degrade SAs better. Moreover, biochar (BC) or DOM released from BC will promote the electron transfer efficiency and improve the removal rate of antibiotics. The purpose of the paper is to provide a reliable basis for the better study of antibiotic degradation using microorganisms influenced by DOM and iron minerals from the natural environment.