Bacterial screening in Indian coastal regions for efficient polypropylene microplastics biodegradation

Area of Science:

• Environmental Microbiology
• Polymer Science
• Marine Biotechnology

Background:

• Polypropylene (PP) microplastics (MPs) pose a significant environmental threat due to increased usage during the COVID-19 pandemic.
• The resilience of PP MPs necessitates urgent solutions for pollution reduction.

Purpose of the Study:

• To investigate the biodegradation potential of marine bacterial strains on polypropylene microplastics (PP MPs).
• To identify specific bacterial strains capable of degrading PP MPs and characterize the degradation process.

Main Methods:

• Isolation and screening of marine bacteria from Thoundi and Rameshwaram coasts based on hydrophobicity, biofilm formation, and zone of clearance.
• Cultivation of selected bacterial strains with PP MPs for 28 days, monitoring growth, metabolic activity, and viability.
• Analysis of PP MPs degradation using weight loss measurements, UV-Vis DRS, SEM, FT-IR, and 1H NMR spectroscopy.

Main Results:

• Five bacterial strains (Bacillus tropicus, Bacillus cereus, Stenotrophomonas acidaminiphila, and Brucella pseudintermedia) showed increased activity during biodegradation.
• Significant weight loss percentages of PP MPs were observed, ranging from 28.5% to 51.5% after 28 days.
• SEM and spectroscopic analyses (UV-Vis DRS, FT-IR, 1H NMR) confirmed surface alterations, cracks, and cavities on PP MPs, indicating degradation.

Conclusions:

• Marine bacteria possess unique characteristics enabling the degradation of polypropylene microplastics.
• The identified bacterial strains secrete hydrolase enzymes (protease, lipase, esterase) that facilitate plastic degradation.
• These findings highlight the potential of marine bacteria for bioremediation of plastic waste and environmental conservation.