Biodegradation Potential of Microplastics by Comamonas testosteroni in Wastewater and Sludge

Comamonas testosteroni is an aerobic, Gram-negative bacterium belonging to the class of β-proteobacteria that is naturally present in soils, wastewater and sludge. It has recently gained popularity for its ability to act as a biocatalyst for the degradation of microplastics and other complex organics. Microplastics are globally considered as ubiquitous pollutants due to the increased use of polymers (plastics) which break down over time. In the urban water cycle, the drinking water treatment plants and the wastewater treatment plants are the first and last barriers to microplastics pollution, respectively. While conventional water and wastewater treatment has seen continuous technological improvements in producing cleaner effluents, industry technology adoption for the targeted removal of microplastics has been minimal. Therefore, the treatment of microplastics in soils and wastewater is of growing interest, and understanding C. testosteroni may provide insight into biological treatment and degradation of these pollutants. This review provides a summary of (1) favorable microbiological and environmental properties of C. testosteroni that lend themselves to bioremediation; (2) evidence of the bacterium’s ability to degrade microplastics, steroids, and organic pollutants; (3) implementation potential in the wastewater treatment process train; and (4) challenges and limitations in its application for microplastics biodegradation. Overall, while treatment applications of C. testosteroni through inoculation of media such as soil and wastewater are mentioned, further research into C. testosteroni concentrations found typically at wastewater treatment facilities would be beneficial.