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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
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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
Recycling of plastic waste Say NO to indiscriminate use of plastic Measures • 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 Burning releases a host of poisonous chemicals into the air
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 Chemically synthesized by including some bonds susceptible to enzymatic degradation Eg. Polylactides Polyglycolic acids Polyethylenesuccinate (PES) Polyurethane (PUR) Naturally accumulated by bacteria Eg. Polyhydroxyalkanoates (PHA) such as polyhydroxybutyrate (PHB)
Selection strategy Serial dilutions 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 Incubation at 30 °C for 3 to 6 days
WEIGHT LOSS-23mg RATE OF DEGRADATION-1.15mg/day
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
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 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.
Increased colonization and reproduction efficiency for biofilm-harvested cells