The Rising Tide of Plastic Pollution: Exploring Bacillus sp. for Sustainable Microbial Degradation of Polyethylene

The global production of plastic has reached unprecedented levels, with polyethylene (PE) being one of the most widely used polymers, accounting for the largest market share. However, the extensive usage of PE has led to significant environmental challenges due to its recalcitrant nature and resistance to degradation. To address this pressing issue, effective degradation processes for PE are essential. Physical and chemical degradation routes for PE are discussed, but microbial degradation emerges as a promising, eco-friendly approach to tackle plastic waste. However, the widespread use of transparent and non-transparent high-density polyethylene (HDPE) presents another challenge in their disposal alongside complex mixtures of wet waste, making their separation difficult. Notably, Bacillus sp. has garnered attention for its potential in biodegradation abilities for various petroleum-based plastics, including PE. This study addresses the gap in HDPE biodegradation research by comparing the degradation of transparent and non-transparent HDPE using Bacillus sp. The biodegradation treatment process involved inoculating bacterial cultures into PE sheets as a carbon source and monitoring their cell growth over 125 days under controlled conditions. Furthermore, the post-degradation PE was characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, surface roughness evaluation, tensile testing, and X-ray diffraction for crystallinity calculation. Bacillus sp. effectively degraded both T-PE and NT-PE, with 1.97% and 4.66% weight loss, respectively. The crystallinity of T-PE was higher than NT-PE, potentially hindering bacterial degradation. Biofilm formation, decrease in tensile strength, and surface erosion further supported the degradation process, making Bacillus sp. a potential candidate for plastic waste management. [GRAPHICS]