An Insight Into Bioremediation of Synthetic Polymers (Plastics) Dr. Alok Kumar Sil Department of Microbiology University of Calcutta

Plastics are widely used in daily life and industrial sectors

Merits :  High tensile strength  Light weight  Long lasting Demerits :  Non-biodegradability  Retention of plastic in soil and water leads to major environmental hazard

Measures Say NO to indiscriminate use of plastic Recycling of plastic waste Demerits Recycling of plastic waste  Recycling is labor intensive and not cost effective  Often the bi-product or end-product of recycling may be toxic or hazardous

Burning releases a host of poisonous chemicals into the air Burning

Bioremediation  If properly identified, microbe-mediated degradation can be applied in situ making the process cost effective and non-laborious  In most cases microbial degradation of plastics is hazard free and yields non-toxic breakdown products

Biodegradable Polymers Polymers containing bonds susceptible to enzymatic degradation Naturally accumulated by bacteria Eg. Polyhydroxyalkanoates (PHA) such as polyhydroxybutyrate (PHB ) Chemically synthesized by including some bonds susceptible to enzymatic degradation Eg. Polylactides Polyglycolic acids Polyethylenesuccinate (PES) Polyurethane (PUR)

Incubation at 30 °C for 3 to 6 days Collection of soil sample from the solid waste ground Spreading of the diluted soil samples on agar plates containing PES as the sole carbon source Selection strategy Serial dilutions

WEIGHT LOSS-23mg RATE OF DEGRADATION-1.15mg/day

Degradation

CONCLUSION Cell surface hydrophobicity of the bacteria is responsible for its enhanced attachment to the polymer surface that leads to better degradation thorough biofilm formation

AdditiveConcentration (in %) Weight loss (in %) after 45 days of incubation None05±1 Tween ± ±1 Mineral oil 0.018± ±2 Effects of Tween 80 and mineral oil on LDPE-degradation by Pseudomonas sp AKS2.

Better attachment leads to formation of biofilm that provides the organism a milieu conducive for better execution of biodegradation.

AKS2 cells develops viable microbial population in biofilm on polyethylene surface

Biofilm harvested cells have higher reproduction ability

Biofilm-harvested cells exhibit increased functional diversity and metabolic activity

Biofilm cells exhibited increased hydrolytic activity and functional homogeneity in biofilm

Biofilm-harvested cells exhibit higher level of cell surface hydrophobicity

Biofilm cells exhibited higher metabolic activities higher functional diversities higher level of functional homogeneity higher surface hydrophobicity and thus increased fitness Taken together, degradation of polymer by biofilm cells can be attributed to the adaptiveness resulting in the modulation enzymatic activities and surface hydrophobicity.

Thank you

Increased colonization and reproduction efficiency for biofilm-harvested cells