Hydrocarbons are major constituents of crude oil and petroleum. They can be biodegraded by naturally-occurring microorganisms in freshwater and marine environments under a variety of aerobic and anaerobic conditions. Oxygen, nitrate, or sulfates are sometimes added as electron acceptors to enhance biodegradation rates.

1. ‘BIODEGRADATION OF
HYDROCARBON’
Dr. Rachana Choudhary
Asstt. Prof.(MICROBIOLOGY)

2. SYNOPSIS
 INTRODUCTION.
 BIODEGRADATION PROCESS.
 MICROBES INVOLVED.
 REACTIONS IN BIODEGRADATION PROCESS.
 BIODEGRADATION OF HYDROCARBONS.
a) aromatic hydrocarbon.
b) polycyclic hydrocarbon.
c) halogenated hydrocarbon.
 FACTORS AFFECTING BIODEGRADATION.
 GENETIC ENGEENERING FOR BIODEGRADATION.
 CURRENT STATUS
 CONCLUSION.
 REFERENCE.

3. INTRODUCTION
Biodegradation is a phenomena of biological
transformation of organic compounds by living
organisms where as,
Biotransformation Means incomplete
biodegradation of organic compounds.

4. What is xenobiotic compound?
Xenos means (foreign) so , it refers to
unnatural foreign and synthetic chemicals
such as pesticides ,herbicides ,refrigerants
solvents and other organic compounds.

5. Properties of xenobiotic compounds.
 They become recalcitrant i.e resist biodegradation
and persist in environment.
 Highily stable.
 Insoluble in water or adsorbed to external matrices.
 Larger molecular size.
 Lack of permease needed for transport into microbial
cells.

6. BIOTRANSFORMATION
MINERALIZATION ACCUMULATION POLYMERIZATION
XENOBIOTICS
FATE OF XENOBIOTIC COMPOUNDS

7. BIODEGRADATION PROCESS
Organic
molecules cell Co2 ,H2o
ph
Inorganic
nutrients
temp
Other
metabolic
products
Molecular oxygen New cells

8. LIST OF SOME XENOBIOTIC
COMPOUNDS.
 DICHLOROBENZENE
 POLYCYCLIC AROMATIC HYDROCARBIN.
 DDT
 ALDRIN
 CARBON TETRECHLORIDE.
 BHC
 HEXACHLOROETHANE

9. MICROBES USED IN BIODEGRADATION
CHEMICALS MICROBES
HYDROCARBONS Pseudomonas, Nocardia,Arthrobacter,
Mycobacterium.
PCBS Pseudomonas, Candida,Alcaligens.
PHENOLICS Pseudomonas, Flavobacterium,
Trichosporum, Bacillus, Aspergillus.
POLY CYCLIC
AROMATIC
COMPOUNDS
Arthrobacter, Nocardia, Alcaligens.

10. METABOLIC EFFECT OF MICROORGANISMS ON
XENOBIOTICS
 DETOXIFICATION
 ACTIVATION
 DEGRADATION
 CONJUGATION

11. Types of Reactions Involved in
Biodegradation
 AEROBIC DEGRADATION.
 ANAEROBIC DEGRADATION.
 SEQUENTIAL DEGRADATION.

12. Hydrocarbon degrades as follows:
HYDROCARBON AICOHOL
ALDEHYDE
FATTY ACID
FURTHER
METABOLIZED

13. BIODEGRADATION OF HYDROCARBON
Hydrocarbons mainly pollutants from oil refineries and
oil spills.It can be degraded by consortium or cocktail
of microorganisms.
eg. Pseudomonas, Corynebacterium,Arthrobacter etc.

14. AROMATIC HYDROCARBON
 Through aerobic process.
 Important micro organism Pseudomonas.
Biodegradation of Aromatic hydrocarbon
require sequence of reaction
1) Removal of side chain
2) Opening of benzene ring

16. CATECHOL AND PROTOCATECHUATE
ORTHO CLEAVAGE META CLEAVAGE
ACETYL-CoA
PYRUVATE
& ALDEHYDE.

18. POLYCYCLIC HYDROCARBON
 Contain two or more
rings.
 1 terminal ring attached
by deoxygenase.
 Other ring is catabolized.

20. FEATURES OF DEGRADATION
 Amide, ester or ether bonds are 1st attacked & further
degradation of the products so generated take place.
 If these bonds are absent or in accessible, aliphatic
chain are degraded.
 If the aliphatic chains are branched, the aromatic
components of complex molecular may be may be
attached.

21. DEGRADATION OF POLYCYCLIC
HYDROCARBON

22. BIODEGRADATION HOLOGENATED
AROMATIC COMPOUNDS
 Rate of the degradation is inversely related to no of
halogen atoms that are originally presents on target
molecule.
 Compounds which higher number of halogen less
easily degrade.
 Involves two steps---
1. Elimination of halogen group.
2. Degradation of non halogenated product molecule.

23. Factors effect the biodegradation of
xenobiotic compound
1. Substrate specificity
2. Electron acceptor
3. Other nutrients
4. Temperature
5. Substrate availability

24. 1. Substrate specificity: Such as for the type of aromatic
compound for the ring position (o-,m-,or p-) and for the
atom or group removed specificities could reside at the
level of enzymes, organisms or broad physiological
group.
2. Electron acceptor: Oxygen, nitrate and sulfate most often
inhabit dehalogenation by anaerobic communities.
3. Other nutrients: addition of various nutrients as electron
donors, Carbon source, Nitrogen source, Phosphorus
source or micronutrient can stimulate the reaction or
support the growth of the microorganisms.

25. 4.Temperature: affected both the activation period and the
rate of biodegradation activity
5.Substrate availability: the hydrophobicity of many
xenobiotic compound facts their biodegradation through
its effect on their availability to microorganisms

26. GENETIC ENGINEERING AS AN EFFICIENT
STEPS FOR BIODEGRADATION
genetic manipulation by plasmid transfer
 1st successful develop of new stain of bacterium
(Pseudomonas) by manipulation of plasmid
transfer was done by Chakrabarty & co worker in
1970.
 Used different plasmid & constructed new
bacterium known as SUPER BUG.
 Degrade camphor, octane, xylene & naphthalene.

27. CREATION OF SUPERBUG

28. XENOBIOTIC AND THE PLASMID
CONTANING GENE
xenobiotic Name of plasmid in
pseudomonas
NAPTHELENE NAH
XYLENE XYL
XYLENE & TOULENE TOL,PWWO,XYL-K
SALICILATE SAL

29. CURRENT STATUS
 Pseudomonas putida:
1. It has been found to be useful in detection of
certain chemicals, such as land mines.
2. It is utilized as a way of detecting land mines
form soil contents.
3. It is found that there is a linkage between the
bacteria ability to degrade TNT & explosive
compound found in land mines.

30.  Nitrosomonas europea:
1. It has nitrogen oxidizing properties.
2. Its metabolism has been studied under ammonia rich
conditions and is recognized as limiting reactants in
the conversion of ammonia.
 Methylibium petroleiphilum:
1. it has ability to completely mineralize methyl tert -
butyl ether (MTBE) ,a gasoline additive.
2. It is capable of consuming diverse range of gasoline
derivatives as its sole carbon source.

31. CONCLUSION
Biological degradation or simply
degradation is considered as a phenomenon of
biological transformation of organic compounds
by living organisms particularly microbes.
Microbial degradation of organic
compounds include processes of aerobic and
anaerobic degradation.

32. REFERENCE
 Textbook of Microbiology by Dubey & Maheshwari.
 Microbiology by R.P.Singh.
 Introduction Microbiology by-Brooke
 Principle of Biochemistry by- Nelson Cox &
Lehninger
 Principle of Microbiology- Prescott 7th addition

33. THANK YOU