Degradation of High Density Polyethylene (HDPE) Through Bacterial Strain from Cow Faeces

The prime objective of our research was to assess the efficiency of fecal bacteria Brevibacillus parabrevis CGK45 from cow in the degradation of HDPE plastic films without any physical or chemical pre-treatment. The biodegradation studies were conducted considering various parameters such as percent weight loss and half-life of HDPE film, biomass of surface adhered cells in terms of protein content as well as viability of bacterial biofilm (CFU/cm2) on plastic surface, and hydrophobicity of bacterial culture. The extent of biodegradation was assessed by implementation of various techniques i.e., Field Emission Scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared Spectroscopy (FTIR). The bacterial strain was identified as Brevibacillus parabrevis CGK45 (Accession number MW965577) by phylogenetic analysis using 16S rRNA gene sequence homology. A significant weight loss (4.03%) in the HDPE film treated with strain CGK45 was observed after 90 days. The SEM analysis visualized remarkable bacterial colonization as well as structural changes in the surface micromorphology on HDPE surface. Furthermore, SEM-EDX analysis showed excellent reduction in the atomic percentage of carbon content (2.2%) whereas FTIR analysis confirmed the conformational shifting of peak and formation of new functional groups [ester (1290 cm-1) and alcohol (1368 cm-1)] apparently due to bacterial biofilm biodegradation. The findings of our investigation provides an insight into the ability of cow dung strain B. parabrevis CGK45 in the colonization and utilization of high density polyethylene as a sole carbon source proving its suitability for future environment friendly degradation studies.