A Study on Comparison of Efficiency of Low-Density Polythene (LDPE) Degradation Under Aerobic and Anaerobic Conditions by Microorganisms Isolated from Soil

Abstract

Plastic has many desirable properties and thus, possesses several varied applications. This has led to a rise in its production and over the years, it has caused plastic pollution. Biodegradation is an affordable and more environment-friendly method compared to the other techniques currently available to eliminate plastic. The aim of this study was to isolate LDPE degrading microbes from soil samples that were collected from 4 different sources in Mumbai and compare their respective LDPE % degradation rates. Isolation of potential plastic degraders was carried out on Bushnell Haas agar that was overlaid with LDPE strips. The final biodegradation rate was calculated by the weight loss reduction method after an incubation period of one month under aerobic and anaerobic conditions. For identification of the bacteria, gram staining and Matrix Assisted Laser Desorption/Ionization- Time of Flight (MALDI-TOF) Mass Spectroscopy were performed and several colony characteristics were studied. For identification of fungi, Potato Dextrose agar containing chloramphenicol was used as the selective media, and Lacto Phenol Cotton Blue staining was performed. Two facultative anaerobic bacterial isolates, Bacillus sp. and Staphylococcus cohnii ssp. urealyticus with LDPE degradation rates of 9.8% and 5.57% respectively, and a highly aerobic fungus, Aspergillus niger, with a degradation rate of 12.13% were found. Fungi showed the maximum rate of biodegradation. Bacillus species exhibited an almost double degradation capacity as compared to that of Staphylococcus species. To improve the biodegradation capacity, the optimum conditions for microbial growth and enzyme production can be assessed and these findings can be applied commercially on a larger scale.