2. INTRODUCTION
Is the phenomenon of biological transformation of
organic compounds by living organisms particularly
microorganisms.
It basically involves the conversion of complex organic
molecules to simpler ones.
The term biotransformation is used for incomplete
biodegradation of organic compounds involving one or a
few reaction.
Is a very important property for toxic chemicals, because
if biodegradation rate is high, the concentration &
thereby the toxic effect will be reduced rapidly.
The range of biodegradation rate is very wide from
readily biodegradable compounds to very refractory
compounds that have a biological half life of several
years.
4. TYPES
Bio mineralization
Microorganisms convert organic waste into
chemical organic matter such as water & Coշ
Ex: shells of invertebrates.
Bio transformation
A part of organic matter is degraded, remaining
part is converted into smaller chain organic
compounds.
Ex: fermentation of sugar into alcohol
5. MECHANISM
The process of biodegradation can be divided
into 3 stages
1. Bio deterioration
2. Bio fragmentation
3. Assimilation
Bio deterioration
◦ Surface level degradation that modifies the
mechanical, physical & chemical properties of the
material.
◦ Occurs when the material is exposed to abiotic factors
in the outdoor environment.
6. Bio fragmentation
◦ Is the lytic process in which bonds within a polymer are
cleaved generating oligomers & monomers in its place.
◦ Can be aerobic or anaerobic.
Assimilation
◦ The resulting products from bio fragmentation are then
integrated into microbial cells.
◦ Once inside the cell, products enter catabolic pathways that
either lead to production of ATP/elements of cell structure.
7. FACTORS AFFECTING
Surface factors influence biodegradation;these
include chemical nature of xenobiotic, the capability
of individual microorganism, nutrient & oxygen
supply, temperature, pH & redox potential.
Among these the chemical nature of substrate that has
to be degraded is very important.
Some of the relevant features are:
◦ Aliphatic compounds are more easily degraded than
aromatic compounds.
◦ Presence of cyclic ring structure & length chain or branches
decrease the efficiency of biodegradation.
8. ◦ Water soluble compounds are more easily degraded.
◦ Molecular orientation of aromatic compounds influence
biodegradation
ortho > para > meta
◦ Presence of halogen inhibit biodegradation.
9. There are 2 recent developments that enhance
biodegradation by microorganisms
Bio stimulation
◦ Process by which microbial activity can be enhanced by
increased supply of nutrients/addition of certain stimulating
agents.
Bio augmentation
◦ Increase biodegradation through manipulation of genes.
