environment, after they are acted upon by bacteria, fungi and plants. Microorganisms work as biocatalysts and help in the process of biochemical and metabolic
reactions that degrade the pollutant in question, although they perform against the
pollutants only if they have support of compounds to help them generate energy and
nutrients for the production of more cells. If the pollutants and microorganisms are
not in contact, then the rate of reaction may slow down to a great extend (Abatenh
et al. 2017).
3.5.1 Energy Sources
Bacteria have the ability of reducing the organic matter to behave as energy sources.
Average oxidation state of carbon decides whether it can act as an energy source for
an aerobic heterotrophic organism.
High oxidation states provide low energy yields, thus the process of degradation
may be slow. There are various factors which are involved and result in the microbial
degradation, viz. biomass concentration, microbial diversity and enzymatic or metabolic activities of the microbes. Acclimation period of the microbes are affected by
the physico-chemical characteristics, molecular structure and concentration of the
substrate along with a number of environmental factors like pH, temperature,
moisture content, availability of electron acceptors and carbon and energy sources
(Boopathy 2000).
3.5.2 Bioavailability
The rate of conversion of contaminants by the microbes during bioremediation is
determined by the rate of contaminant uptake and metabolism (Boopathy 2000). The
contaminated explosives would not undergo degradation even in 50 years, if mass
factor is a limiting factor (Boopathy and Manning 1999). Conversion of larger soil
particles into smaller ones by breaking and mixing of the soil particles increases the
surface area to a great extent, hence enhances the degradation rate (Manning et al.
1995). Physico-chemical processes, viz. sorption, desorption, diffusion and dissolution, decide whether the contaminant is bioavailable or not. If the rate of mass
transfer of contaminants is zero, then the contaminants are not available to the
degrading microbes. This decrease in bioavailability is known as ageing or
weathering (Boopathy and Manning 1999).
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S. K. Yadav
reactions that degrade the pollutant in question, although they perform against the
pollutants only if they have support of compounds to help them generate energy and
nutrients for the production of more cells. If the pollutants and microorganisms are
not in contact, then the rate of reaction may slow down to a great extend (Abatenh
et al. 2017).
3.5.1 Energy Sources
Bacteria have the ability of reducing the organic matter to behave as energy sources.
Average oxidation state of carbon decides whether it can act as an energy source for
an aerobic heterotrophic organism.
High oxidation states provide low energy yields, thus the process of degradation
may be slow. There are various factors which are involved and result in the microbial
degradation, viz. biomass concentration, microbial diversity and enzymatic or metabolic activities of the microbes. Acclimation period of the microbes are affected by
the physico-chemical characteristics, molecular structure and concentration of the
substrate along with a number of environmental factors like pH, temperature,
moisture content, availability of electron acceptors and carbon and energy sources
(Boopathy 2000).
3.5.2 Bioavailability
The rate of conversion of contaminants by the microbes during bioremediation is
determined by the rate of contaminant uptake and metabolism (Boopathy 2000). The
contaminated explosives would not undergo degradation even in 50 years, if mass
factor is a limiting factor (Boopathy and Manning 1999). Conversion of larger soil
particles into smaller ones by breaking and mixing of the soil particles increases the
surface area to a great extent, hence enhances the degradation rate (Manning et al.
1995). Physico-chemical processes, viz. sorption, desorption, diffusion and dissolution, decide whether the contaminant is bioavailable or not. If the rate of mass
transfer of contaminants is zero, then the contaminants are not available to the
degrading microbes. This decrease in bioavailability is known as ageing or
weathering (Boopathy and Manning 1999).
94
S. K. Yadav