Exploring the Role of Plant Growth-Promoting Bacteria in Biodegradation of Plastic: A Review

The issue of plastic waste has increased substantially due to the extensive employment of man-made polymers across multiple industries. These plastics derived from fossil fuels, such as polyethylene, polystyrene, and polypropylene, are difficult for nature to break down independently. Fortuitously, some microbes have developed the potential through evolutionary adaptation to break down these long-lasting synthetic compounds. Certain microorganisms have evolved the ability to decompose these durable polymers. Some beneficial soil bacteria called plant growth-promoting bacteria have shown promise in both supporting plant growth and development and degrading plastics. Various species of Bacillus and Pseudomonas contain enzymes enabling them to metabolize polyethylene. Rhodococcus species possess similar complimentary enzyme complexes suited for polypropylene degradation. These microbes employ hydrolytic and oxidative enzymes to initiate the plastic breakdown process. Additional soil organisms then further facilitate the mineralization of the fragmented polymers. The nitrogen-fixing Rhizobium can attack polystyrene. The multi-step mechanism often starts with surface oxidation catalyzed by bacterial enzymes. Multiple studies have isolated strains like Brevibacillus borstelensis and photosynthetic Rhodopseudomonas able to consume polyethylene. Meanwhile, certain Streptomyces also have polypropylene depolymerization potential. Overall, applying plastic-eating microbes offers hope for plastic waste management while lessening environmental harm and propelling the shift to a circular economy.

Graphical Abstract