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Bioavailability Constraints in the Uptake of Oil & Hydrocarbons by Microorganisms

Bioavailability Constraints in the Uptake of Oil & Hydrocarbons by Microorganisms. Prof. Suparna Mukherji Centre for Environmental Science & Engineering IIT, Bombay. Definitions and Keywords. 1.

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Bioavailability Constraints in the Uptake of Oil & Hydrocarbons by Microorganisms

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  1. Bioavailability Constraints in the Uptake of Oil & Hydrocarbons by Microorganisms Prof. Suparna Mukherji Centre for Environmental Science & Engineering IIT, Bombay

  2. Definitions and Keywords 1 • NAPLs/Oils : Oil comprises of a series of paraffins, aromatics and asphaltenes which are long chain hydrocarbons, hence is immiscible in water. Oil spills on soil or water are toxic, carcinogenic, and hazardous to the environment. • NAPL: Non-aqueous phase liquids • Being immiscible in aqueous phase their bioavailability to the microorganisms is hindered and hence a major challenge for bioremediation. • Add more slides if required 2 3 4 5

  3. Definitions and Keywords 1 • Bioavailability: availability to microorganisms, it is dependent on mass transfer rates i.e. rate of transfer of pollutants (oils & hydrocarbons) to the aqueous phase. • Bioavailability limitations can be overcome by microbial adherence to oil and direct interfacial uptake of components from the oil phase; and by release of surfactants that cause pseudosolubilization or emulsification of oil. • Surfactants: surface active agents, long chain amphiphillic molecules, can be anionic, cationic, zwitterionic, and non ionic, classified as chemical surfactants and biosurfactants depending upon their origin. • Add more slides if required 2 3 4 5

  4. Definitions and Keywords 1 • Micellization: Micellar solubilisation occurs when the surfactant concentration exceeds CMC (critical micelle concentration), aqueous solubilisation is enhanced by incorporation of hydrophobic molecules into the surfactant micelles. • Sorption: transfer from solution phase onto a solid matrix, includes both • Adsorption: accumulation at the interphase • Absorption: uniform distribution in the solid phase • Add more slides if required 2 3 4 5

  5. INSTRUCTIONS SLIDE Concept details: 1 2 3 4 5

  6. INSTRUCTIONS SLIDE Concept details: 1 2 3 4 5

  7. Concept details 1 2 3 4 5

  8. Concept details 1 2 3 4 5

  9. Questionnaire 1 1. How does the surfactant influence the surface tension? Answers: (a) increases (b) decreases (c) no effect (d)‏ none of these 2. Bioavailability constraint of oils is due to Answers: (a) hydrophobicity (b) immissibility in aqueous phase (c) hydrophilicity (d)‏ both (a) & (b)‏ 3. Micelle formation by surfactants occurs at concentration Answers: (a) does not occur ( b) above CMC (c) below CMC (d) none of these 4. Bioavailability limitations can be avoided by (a) Use of surfactants ( b) direct uptake by microorganisms (c) both a) & b) d) none 2 3 4 5

  10. Links for further reading 1 Singh, A., Van Hamme, J.D., Ward, O.P., 2007. Surfactants in microbiology and biotechnology: Part 2. Application aspects. Biotechnology Advances 25, 99-121. Volkering, F., Breure, A.M., Rulkens, W.H., 1998. Microbiological aspects of surfactant use for biological soil remediation. Biodegradation 8, 401- 417. Surfactant Science Series: a series of books describing the nature , behaiviour, mechanisms, & applications related to surfactants. 2 3 4 5

  11. Thank you

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