Transformation mechanism of aromatic hydrocarbon pollutants based on electroactive microorganisms

Abstract:

Aromatic hydrocarbons, a class of organic compounds with one or more benzene rings, are ubiquitous in the natural environment. They are difficult be degraded naturally and thus easy to be bioaccumulated, posing a huge threat to the environment. Biological degradation seems to be the mainstream method for the transformation of organic compounds, and electroactive microorganisms have great potential in the removal of aromatic hydrocarbons because of their unique extracellular electron transport ability and physiological metabolism mode. They can finally achieve the degradation and mineralization of aromatic hydrocarbon pollutants by combining reductive dehalogenation and denitrification and oxidative ring cleavage. In this paper, we focused on the main reduction/oxidation reaction mechanisms in the degradation of aromatic hydrocarbon pollutants by electroactive microorganisms, summarized the key enzyme activities, metabolic pathways, and transformation mechanism of electroactive microorganisms in the reductive dehalogenation and denitrification, analyzed the ring cleavage modes and metabolic pathways of electroactive microorganisms under different oxygen-containing conditions, and improved the extracellular electron transport process of the microorganisms by regulating microbial extracellular polymers and adding conductive materials. Moreover, we discussed the influence of electrode potential, electrode materials, and environmental factors such as electrolyte properties and temperature on the degradation of aromatic hydrocarbon compounds, and the feasibility of enhanced biodegradation strategies for aromatic hydrocarbon pollutants. Finally, in order to provide theoretical and technical reference for accelerating the engineering application of bioelectrochemical systems, we summed up the directions of future potential research in the related fields of electroactive microbial degradation technology.