Singh, BrajeshwarSharma, Ankita2024-07-112024-07-112024-06-24Studies on plastic biodegradability potential of bacteria and fungi isolated from dumping ground of Jammu region37201https://krishikosh.egranth.ac.in/handle/1/5810211787The current study entitled “Studies on plastic biodegradability potential of bacteria and fungi isolated from dumping ground of Jammu region” was conducted at Division of Microbiology, FBSc, SKUAST-Jammu. The research focused on isolating polyethylene degrading microbial population from municipal waste dumping grounds of Jammu region. Sixty two bacteria and thirty one fungi were isolated from two municipal waste dumping sites on basal media using low density polyethylene films as sole carbon source subjected to an experiment designed for ascertaining their potential to degrade low density polyethylene. After sixty days of incubation, the low density polyethylene films were observed for weight loss, tensile strength loss and wear and tear under scanning electron microscopy. These finding confirmed biodegradability potential of three bacterial isolates (MB-5, MB-12, MB-57) and three fungal isolates (MF-14, MF-16, MF-20). In case of bacterial isolates, maximum percent weight loss (23.87±02.31%), maximum percent loss in tensile strength (74.35±05.18%) was recorded with MB-57 at pH 7.0. In case of fungal isolates, MF-16 showed maximum percent weight loss (37.66±06.24%), and maximum percent loss in tensile strength (92.30%±06.98) at pH 3.5. In scanning microscopy analysis, scions/ cracks/ holes/ fissures were found on the surface of the degraded polyethylene film that confirmed biodegradation. Gram’s staining technique revealed that potential bacterial isolates MB-5 and MB-12 were Gram positive and MB-57 was Gram negative. Furthermore, all the three potential bacterial isolates were identified using a biochemical test kit (Hi25TM Media®). Molecular identification of potential bacterial isolates was accomplished through 16s rRNA gene sequencing and potential fungal isolates through 18s rRNA gene sequencing. Extract obtained after sixty days of biodegradation experiment was subjected to gas chromatography and mass spectroscopy analysis to study toxic by products produced by biodegradation of polyethylene film. The toxicity effect of polyethylene degraded byproduct on wheat seeds and macrophages cell lines (RAW 264.7 macrophages cell) was also analysed. In case of bacterial isolates, the major polyethylene degradaing by-products produced were Dotriacontane, 2 and 3- methyl triacontane and Hexadecanoic acid dissolved in diethyl ether were recorded. The by product recorded with fungal isolates were 3-Methyltriacontane, Oxalic acid, and Nonyl octacosyl ether. Among both bacterial and fungal isolates, polyethylene degraded products of bacterial isolates (MB-5 and MB-57) showed maximum inhibitory effect on seed germination percentage, elongation inhibition rate and germination index rate as compared to fungal isolates. Polyethylene degrading product of both bacterial isolates MB-57 and fungal isolates MB-20 showed maximum cytotoxicity against macrophages cell lines (RAW 264.7 macrophages cell). The following work reveals that municipal waste disposal sites contains a vast majority of microbes that have the potential to break down plastics and these microbes can be used to potentially develop effective strategies for addressing plastic pollution and its environmental impacts. This research further provides valuable insight that by-products produced due to degradation of plastics have cytotoxic effect on both plant and animal system.EnglishThesis