Investigation of Bacteria with Potential to Facilitate the Degradation of High-Density Polyethylene (Plastic)

Lee, Hoong Yew (2018) Investigation of Bacteria with Potential to Facilitate the Degradation of High-Density Polyethylene (Plastic). Final Year Project (Bachelor), Tunku Abdul Rahman University College.

Text Lee Hoong Yew_Full Text.pdf Restricted to Registered users only Download (3MB)

Abstract

According to Malaysian Plastics Manufacturers Association (MPMA), average Malaysian uses approximately 300 plastic bags per year. Plastic wastes undoubtedly makes a significant contribution of environmental pollution due to its’ non-biodegradable characteristics. This project aims to study a variety of bacteria which has the potential to degrade high-density polyethylene (HDPE). 14 strains of bacteria were selectively screened using customized carbon-depleting plates known as “Mineral Salts” medium. Throughout the 15 days observation, S3-B and S3-C were the only strain showing positive outcome where it only grew in the plate with HDPE plastic sheet, suggesting that they fully utilised it as the sole carbon source for survival. “Bacteria Adhesion to Hydrocarbon” (BATH) assay showed that S3-C has a significant lower absorbance of aqueous phase after phase separation in comparison to S3-B, where their mean absorbance is ranged at 0.7360-1.0977 and 1.1027-1.1773 respectively (p<0.05). This evidence indicates that S3-C has higher ability to attach to plastic than S3-B. Their cell viability was quantified using Tetrazolium Chloride (TTC) reduction test and I discovered that S3-C was having higher potential to utilize HDPE plastics for growth as its mean absorbance in Day 4 was still increasing significantly from 0.0277 to 0.0423. Inversely, S3-B was experiencing slow growth even in the presence of HDPE plastic sheet as their mean absorbance in Day 4 was remained at approximately 0.02. To conclude, I have determined that strains S3-B and S3-C have notable potential to be the plastic degrading bacteria.