ISOLATION OF POLYVINYL CHLORIDE DEGRADING BACTERIA FROM OPEN DUMPING SITE, ISLAMABAD, PAKISTAN

Abstract

Plastics have a vital role in our lives. Many items of everyday life come from different types of plastic, from films to packaging, including blankets, containers and bags to building materials, electronic applications and electrical equipment. Lack of biodegradability of these products draws public awareness to increase in environmental pollution problem. In the current study, low molecular weight polyvinyl chloride is biodegraded using bacterial strains isolated from open dumping site situated on the upper bank of Korang River, Islamabad Expressway. Four bacterial strains were screened and used as consortium to degrade PVC under varying physical and chemical experimental conditions in minimal salt medium for 15 days at 30°C. Effect of different cometabolites, light, Ultra-violet radiations and pH was evaluated to assess biodegradation of PVC pieces. Maximum bacterial growth in terms of CFU/ml, 665/ml, was observed when Glycerol as co-metabolite was added in the medium. Non UV pre-treated sample showed more growth, 591/ml, as compared to UV pretreated samples. 9 pH showed maximum stability and growth in terms of CFU/ml that is, 212/ml by the end of the experiment. Chemical changes were observed using Fourier Transform Infrared Spectroscopy (FTIR) and physical changes were observed using Scanning Electron Microscopy (SEM). FTIR showed breakdown and formation of many compounds as evident by new peaks formation in microbial treated PVC samples in comparison with the control (untreated). SEM showed structural and surface changes in PVC in the form of depression, pits, erosions, discoloration and small holes. Clear image of biofilm on the surface of treated PVC samples in the form of rod shaped bacteria was observed. In SEM images it can be concluded that bacterial consortium was able to bring about chemical and physical changes in PVC pieces which gives positive indication of occurrence of biodegradation processes taking place.