Preliminary observation of bacterial biofilm communities on plastic litters and their surface degradation in two coastal areas of Tuticorin, India

The accumulation of plastic litter in the marine environment is a growing ecological concern. Microorganisms can create a biofilm on the surface of plastic litters making them more hazardous. Although plastics are difficult to biodegrade, they can act as substrate for microorganism attachment. To investigate this problem, biofilm coated plastic litters such as covers, films and ropes were collected randomly from Muthunagar and Inigonagar in Tuticorin coastal areas and analysed using FTIR-ATR. The spectra obtained demonstrate the presence of Polyethylene (PE), Polypropylene (PP), Polystyrene (PS) and Polyamide (PA). The concentration of biofilm formed on the surface of plastics is higher in Inigonagar compared to Muthunagar coastal area. Investigations were also conducted into the bacterial development on the plastic surface and in the surrounding water and sediment. Several bacterial communities including human pathogens namely Faecal coliform, E. coli, Salmonella sp., Streptococcus sp., Staphylococcus sp., Pseudomonas sp., Bacillus sp., Klebsiella sp., and Vibrio sp. were found to be associated with the collected plastic litters. We confirmed the weathering of plastic litters by carbonyl and vinyl peaks formation. According to the Carbonyl Index values plastic litters collected from Inigonagar exhibit higher degree of degradation compared to Muthunagar coastal areas. The present study could provide significant baseline information for both plastic pollution and biofilm composition in Muthunagar and Inigonagar coastal areas.