1. Biodegradation of
Petroleum Hydrocarbons
By: Sheikh Amir Hamza.
256-FBAS-BSBT-F12

2. What are petrochemicals?
 Chemicals derived from petroleum or natural
gas.
 Major petrochemicals are acetylene, benzene,
ethane, ethylene, methane, propane, and
hydrogen.
 A huge variety of products are made with
petrochemicals.
 Including plastics, soaps, pharmaceuticals,
fertilizers, pesticides, detergents.

3. Molecular structures of
hydrocarbons.

4. Cons of Hydrocarbons
HCS belong to the family of carcinogens
and neurotoxic organic pollutants.
Main cause of water and soil pollution.
Accumulation of pollutants in living cells
may cause death or mutations.
Their removal is necessary.

5. Microbial Degradation of
Petroleum Hydrocarbons
Biodegradation of HCS is a complex process
depending on:
 the nature
 Amount of the hydrocarbons present
Petroleum HCS divided into four classes:
 The alephatics
 The aromatics
 The asphaltenes (phenols, fatty acids,
ketones, esters, and porphyrins),
 And the resins (pyridines, quinolines,
carbazoles, sulfoxides, and amides

6. Approaches In HC’s Degradation
 Bioaugmentation:
It is the introduction of biodegrading
microbes at the site of spill to aid the
indigenous microbial species.
 Biostimulation:
In Biostimulation nutrients and growth
limiting factors are added to soil
indigenous microbes.

7. Natural mechanism for degrading
HCS
 by bacteria, yeast, and fungi.
 Mix population of these microbes are
more efficient.
 Bacteria are the most active agents in
petroleum degradation.

8. Enzymes and microbes
Participating in Degradation of
HCS
Enzymes Substrates Microorganis
ms
Referenc
es
Soluble Methane
Monooxygenases
C1–C8 alkanes alkenes
and cycloalkanes
Methylococcus
Methylomonas
McDonald
et al.
Particulate Methane
Monooxygenases
C1–C5 (halogenated)
alkanes and
cycloalkanes
Methylobacter
Methylococcus
McDonald
et al.
AlkB related
Alkane
Hydroxylases
C5–C16 alkanes, fatty
acids, alkyl benzenes,
cycloalkanes
Pseudomonas
Burkholderia
Rhodococcus
Mycobacterium
Jan et al.
Eukaryotic P450 C10–C16 alkanes, fatty
acids
Candida
maltosa
Candida
tropicalis
Yarrowia
lipolytica
Iida et al

9. Mechanism of Petroleum HCS
Degradation

10. Mechanism of Petroleum HCS
Degradation
 Biosynthesis of cell biomass occurs from
the central precursor metabolites, for
example,
 acetyl-CoA, succinate, pyruvate.
Other mechanisms are
 Attachment of microbial cells to the
substrates.
 Production of biosurfactsants.

11. Biodegradation of Petroleum
compounds
Petroleum compounds are categorized into
2 groups
 Aliphatic hydrocarbon e.g. alkane,
alcohol, aldehyde
 Aromatic hydrocarbon e.g. benzene,
phenol, toluene, catechol

12. Straight chain Aliphatic
Hydrocarbons

13. Cyclic Aromatic Hydrocarbons

14. Anaerobic degradation
 Under nitrate-reducing bacteria
 Sulfate-reducing bacteria

15. Factors Influencing Petroleum
HCS Degradation
A number of limiting factors affect the
biodegradation of petroleum HCS
 Chemistry of HCS
 Physiological factors
 Nutrients

16. Temperature Range

17. Conclusion
 Cleaning up of petroleum HCS is a real world
problem.
 It depends on the indigenous microorganisms to
transform or mineralize the organic
contaminants.
 Microbial degradation process aids the
elimination of spilled oil from the environment
after critical removal of large amounts of the oil
by various physical and chemical methods.
 This is possible because microorganisms have
enzyme systems to degrade and utilize different
hydrocarbons as a source of carbon and energy.
 Therefore, based on the present review, it may
be concluded that microbial degradation can be
considered as a key component in the cleanup
strategy for petroleum hydrocarbon remediation