Biodegradation of Low Density Polyethylene (LDPE) using marine bacteria isolated from tropical beaches of megacity Mumbai

Plastics, although as useful and versatile as they are, have led to major environmental pollution. Its resistance to degradation has caused a major global threat to the environment. Plastic waste is disposed of in landfills causing soil pollution, incinerated releasing toxic fumes and causing air pollution, and dumped in the ocean causing a wide range of problems like entanglement and ingestion by marine creatures. Since the introduction of plastic, microorganism, though incapable of degrading it, is known to associate with its surface. Marine ecosystem is one such environment where the disposal of a large amount of plastic waste is found, and microorganisms are known to be associated with it. Hence, the marine environment can serve as a potential source for indigenous plastic-degrading microorganisms. In the following study, plastic pieces rooted deep in sediments from seven recreational beaches in Mumbai were collected for the isolation of possible plastic degrading bacteria associated with the surface of the collected plastic pieces. Altogether, nine isolates were isolated after three months of incubation of collected samples in a medium containing no carbon source. On identification by 16S rRNA sequencing, isolates were confirmed to be Pseudomonas, Bacillus and Lysinibacillus. The NCBI accession numbers were obtained for all the isolates. For further experimentation, only four Pseudomonas isolates (Strains ABFPD01, ABFPD02, ABFPD03 and ABFPD05) and one each isolate of Bacillus and Lysinibacillus were used. In the weight loss experiment, the ABFPD02 & ABFPD03 strains of Pseudomonas degraded 11 % of pre-weighed polyethylene strips in 2 months incubation period. The marine environment needs to be studied extensively for more potential microorganisms for plastic degradation.