High density polyethylene microplastics biodegradation by bacteria isolated from a landfill in Cali, Colombia

Microplastics cause pollution problems because they are difficult to degrade and tend to be easily transported and accumulate in the environment. Biodegradation is a promising solution by exploiting the ability of fungi or bacteria to accelerate the degradation process of microplastics, but this is a topic with several knowledge gaps. To evaluate the ability of microorganisms to degrade high-density polyethylene microplastics, four bacterial strains isolated from a sanitary landfill were selected, in a minimal salt medium with microplastics as the sole carbon source. The selected strains were identified as Tsukamurella sp. strain JP3, Tsukamurella sp. strain JP5+, Pseudomonas aeruginosa (JP5–) and Streptomyces sp. strain JP8. The bioassays were performed with single strains and mixed cultures. Biodegradation was determined by calculating the percentage weight loss of the microplastics and observing changes in their surface structure using scanning electron microscopy (SEM). Biodegradation rates between 6.81 and 18.14% were obtained, with JP5+JP8 being the treatment with the highest percentage, but with no significant differences between treatments. However, SEM showed microbial damage and growth on the surface of microplastics. Therefore, the bacterial strains used would have potential for biodegradation of high-density polyethylene, but it is advisable to continue investigations to determine the conditions and appropriate times to improve biodegradation with these strains.