Identification and degradation potential of microplastics by indigenous bacteria isolated from Putri Cempo Landfill, Surakarta, Indonesia

Plastic waste on agricultural land can break down into microplastics (< 5 mm), which plants can absorb through their roots, potentially inhibiting plant growth. Utilizing microplastic-degrading bacteria isolated from landfills offers a potential solution to microplastic contamination in agriculture. This study aimed to isolate and identify bacteria from the Putri Cempo Landfill and evaluate their ability to degrade different types of plastic contaminants found in agricultural environments. Microorganisms were isolated from soil samples using Soil Extract Media (SEM), and pure cultures were established. Bacterial isolates were tested for their microplastic-degrading potential using polyethylene terephthalate (PET) plastic fragments. Molecular analysis was conducted to determine the taxonomy of the bacteria. Further degradation tests were performed on different types of microplastic contaminants (mulch, polybags, and sacks) to identify the most degradable material. Six bacterial isolates were obtained, with isolates CP1 and CP2 demonstrating microplastic degradation rates of 2.43% and 1.15%, respectively, over a 20-day incubation period. Molecular analysis identified CP1 as Bacillus anthracis str. and CP2 as Bacillus cereus ATCC 14579. Subsequent degradation tests on various agricultural microplastic contaminants revealed that sack materials treated with Bacillus cereus showed the highest degradation rate, with an 8.8% weight reduction, while polybag materials showed the lowest degradation rate, with a weight loss of only 0.59%.