Feasibility study of a co-culture system for PET-degrading bacteria to increase biodegradation performance

Abstract

The rising production and consumption of plastics, coupled with their intrinsic robustness, has resulted in the accumulation of up to 200 million tons of plastic waste in landfills and the environment each year. Of all these synthetic polymers, polyethylene terephthalate (PET) is the most widely used in the world. As environmental microorganisms have begun evolving their own biological means to metabolize plastics, they potentially present a sustainable method to recycle PET and retain its material value for subsequent use through biodegradation. Here, we evaluate the feasibility of using multiple PET-degrading bacterial strains (Thermobifida fusca, Ideonella sakaiensis, Pseudomonas mendocina) concurrently to develop an industrial co-culture solution. The growth behavior of each strain was evaluated at temperatures ranging from 30-60 °C and in a Hipolypepton-based media. UV-treated PET pellets were then incubated in monoculture and co-culture cell suspensions for 2 days, and degradation was measured through a spectrophotometric assay. A 1:1 T. fusca/I. sakaiensis co-culture was found to achieve a higher biodegradation efficiency compared to I. sakaiensis monoculture but not compared to T. fusca monoculture, suggesting the need for further optimization of degradation conditions. Although our studies demonstrate the great potential of biodegradation as a solution for the plastic waste crisis, the direct application of microbes may not be suitable for industrial use when compared to alternative biodegradative methods.