The Detection of Propionate Utilization by Bacteria Isolated from a Plastic Recycling Site

(1) The study aims to utilize a reported approach for culturing mesophilic bacteria from a plastic waste environment; (2) The work revived mesophilic microbial population from an aged PET recycling site using a culture-based approach, and determined the purified isolates in genus level in 16S identification; (3) A total of 59 bacterial isolates were obtained, in which microbial species, including Pseudomonas spp, Rhodococcus spp, and Burkholderia spp were identified as abundance. It was observed that the surviving microbes favoured sodium propionate as a short-chain carbon source for growth, rather than the intended plastic substrate, PET. The preference of sodium propionate utilization by several bacterial isolates, including 5601W (detected as Rhodococcus spp.), 5601Y, 7801, and 7802 (detected as Burkholderia spp.), was confirmed through growth curve analysis and cell enumeration conducted in a medium where sodium propionate served as the sole carbon source.; (4) The microbial demonstration revealed the metabolic complex of microbial communities in the environment and indicated the challenges associated with bacterial isolation from environments with accumulated plastic waste.