Biodegradation of Microplastics by Microorganisms Isolated from Two Mature Landfill Leachates

Abstract Microplastics are contaminants in the form of tiny plastic fragments diluted in terrestrial and aquatic environments. Recently, these contaminants have become a concern due to their negative impact on the quality of life of living things. The isolation and examination of microplastic degrading microorganisms' ability from two large mature landfills were conducted. Therefore, this study aims to obtain bacteria and fungi as bioremediation agents that can degrade microplastics. The isolation process was conducted by direct and indirect (enriched) methods. Nutrient agar and potato dextrose agar media were used either in the form of a full or a tenth of a recipe with the addition of polyethylene, polypropylene, and polystyrene microplastics. Furthermore, indirect isolation used mineral media treated with the same microplastics. Colony morphology was observed to be the difference among isolates. The isolates were selected based on their ability to produce lipase in butter agar, and their ability to use microplastic as the only carbon source was examined. A total of 211 isolates were obtained, consisting of 74 bacteria and 137 fungi. One-third of the total isolates produced lipase. A bacterial isolate with the highest lipase index identified based on the 16S rRNA gene showed that it was Bacillus paramycoides. The isolate used all three types of microplastics, with the highest ability in polystyrene, which was degraded up to 11.12% in 42 days. In conclusion, microorganisms isolated from the landfill leachate have potential as bioremediation agents that degrade microplastics. Keywords: Bacillus, Bacillus paramycoides, Biodegradation, Bioremediation, Landfill, Leachate, Microplastics, Polystyrene