Petroleum biodegradation

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  • Terminologies Defined:Petroleum- a naturally occuring flammable liquid consisting of a complex mixture of hydrocarbons that are found in geologic formations beneath the earths surface.

    Aliphatic Hydrocarbons- any large class of organic compounds whose carbon atoms are joined in straight chains rather than in rings.

  • Interface - part where oil and water meet often occur in large scale.Bioremediation- refers to the process of using microorganisms in cleaning up oil spills and other pollutants.Bioaugmentation- introduction of microorganisms to augment the process.Biostimulation- addition of nutrients and oxygen to stimulate the growth of indigenous microorganisms.

  • Components of petroleumHydrocarbons- main component of Petroleum;

    Characteristics of OilLess dense than water , so it floats forming slicks;Insoluble in Water

  • PRINCIPLES OF BIOREMEDIATIONBioremediation uses microorganisms and other living organisms to transform organic pollutants into less toxic forms.Biodegradation is the initial process that results to bioremediation.

  • FACTORS IN BIOREMEDIATIONExistence of a microbial population capable of degrading the pollutants; The availability of contaminants to the microbial population e.g. oilThe environment factors (type of soil, temperature, pH, the presence of oxygen or other electron acceptors, and nutrients).


    Availability Microbes can be:Indigenous- microorganisms are present in the contaminated site. Biostimulation is needed.Bioaugmentation- introduction of microorganisms from other environment.

  • Bioremediation in Large ScaleGasoline tanks are potential habitats for Hydrocarbon-oxidizing bacteria which can grow in oil-water interface.

  • HYDROCARBON DEGRADATIONHYDROCARBON DECOMPOSERS:Hydrocarbonoclastic Bacteria ( HCB)- Gammaproteobacteria ( Alcanivorax sp., Marinobacter)- Alphabacteria (Rhodobacteriaceae)-Pseudomonas, Alcaligenes, Sphingomonas, Rhodococcus, and Mycobacterium.

  • Hydrocarbon Oxidizing Bacteria Attach to oil slicksMicrobes in SlickMicrobes eating gulf oil

  • Pseudomonas sp.rod

    - A gram-negative enteric rod that are able to grow in extreme environments. Commonly isolated in areas where hydrocarbons are present.

  • Fungi

    - Aspergillus sp.- Mucor sp.- Talaromyces sp.

    Green Algae- cyanobacteria

  • KEY POINTS IN HYDROCARBON DECOMPOSITIONHydrocarbon decomposition is done by hydrocarbon-oxidizing microorganisms.The Process occurs in the presence of oxygen.Microorganisms participate in oil spill cleanup by oxidizing the oil to Carbon Dioxide.

  • Some factors that hasten up the process:1. pH3. inorganic nutrients2. Temperature

    Inorganic Nutrients such as Phosphorus and Nitrogen are important to stimulate microorganisms.

  • Evidences of Petroleum Degradation by Microorganisms

    Dispersal of oil slicks ;Radioisotopic Hydrocarbons as trackers of Oxygen uptake; Fungi bloom is evident if enough sources of food is present; however , when food sources are continously decreasing, the growth of fungi also decreases. Presence of less toxic forms of contaminants.

  • Case Report:March 1989- 11-million-gal oil spill from a tanker Exxon Valdez devastated the shores near Prince William Sound in Alaska. The input of this oil spill has devastating effects both environmentally and economically.

  • Petroleum ProductionAside from the petroleum degradation, microorganisms also aids in petroleum production.Botryococcus braunii a colonial alga is said to excrete long-chain hydrocarbons with 30 to 36 Carbon atoms.It is considered to be a renewable source of petroleum.

  • Bioremediation is not only about genetics and enzymology but also about physiology and ultimately Lorenzo V: Systems biology approaches to bioremediation. Curr Opin Biotechnol 2008, 19:579-589.


  • Evaluation: sheet of yellow paperWhy might the addition of Phosphorus and Nitrogen stimulate oil degradation while adding of glucose might not? (5pts)Microorganisms can thrive anywhere, what is the reason why microorganisms do not degrade gasoline in storage tanks? (5pts)