Biopiles
Biopiles is one of the cleanup techniques where the excavated soil materials are
mixed with hydrocarbons which is treated with biodegradation by oxidation process
by the injection of oxygen. The oxidation process increases the availability of
microbes in soils. The contaminated materials are excavated which is further
mixed with sawdust, sand, compost, nutrients, wood chips, etc. These things
improve the moisture retention, allow the permeability of microbes and stimulate
the biological reactions very fast and to oxidize the hydrocarbons. Biopiles are also
called as compost piles, biomounds, biocells, and bioheaps (Delille et al. 2008).
1.8 Microorganisms and Pollutants
The microorganisms present in the rhizosphere soil can transform the pollutants
from one oxidation state to another. Microbes protect its own structure from metal
toxicity through various mechanisms, namely oxidation, reduction, methylation,
adsorption, etc. Methylation is an important method that play important role in
bioremediation. For example, mercury, bioethylated by a number of bacterial species, namely Alcaligenes faecalis, Bacillus pumilus, Bacillus sp., P. aeruginosa and
Brevibacterium iodinium to gaseous methyl mercury. Environmental factors also
play an important role for the growth and activity of microbes to enhance bioremediation (Vidali 2001). The long-term application of pesticides can also promote
biodegrading enzymes in the indigenous microflora, as they serve as a source of
carbon and energy, making the remediation of pesticide contaminated sites easier
(Qiu et al. 2009).
1.8.1 Degradation of Pesticides by Rhizospheric Microbes
Rhizospheric microorganisms are universal scavengers for decaying or recycling the
waste materials into harmless things. It includes bacteria, fungi and actinomycetes
which are able to eliminate the pesticides from the environment (Parte et al. 2017).
Many researchers reported that soil microorganisms such as Burkholderia,
Arthobacter, Aztobacter and Flavobacterium degraded the pesticides (Shi and
Bending 2007). Single microbe can degrade more than one herbicide and pesticide
and also involved in plant growth promotion and zinc and phosphorus solubilization.
Staphylococcus sp. and Bacillus circulans isolated from the surrounding area of
pesticide production industry degraded 72–76% of endosulfan under aerobic and
facultative anaerobic conditions (Kumar and Philip 2007). In the chemical industry,
various chlorinated compounds are used as the industrial solvents and degraded by
Aminobacter and Mesorhizobium sp. by the secretion of enzymes (Osborn et al.
2010). Organophosphorus pesticides were degraded extensively (Singh 2008).
1 Rhizosphere: Niche for Microbial Rejuvenation and Biodegradation of Pollutants
11
Biopiles is one of the cleanup techniques where the excavated soil materials are
mixed with hydrocarbons which is treated with biodegradation by oxidation process
by the injection of oxygen. The oxidation process increases the availability of
microbes in soils. The contaminated materials are excavated which is further
mixed with sawdust, sand, compost, nutrients, wood chips, etc. These things
improve the moisture retention, allow the permeability of microbes and stimulate
the biological reactions very fast and to oxidize the hydrocarbons. Biopiles are also
called as compost piles, biomounds, biocells, and bioheaps (Delille et al. 2008).
1.8 Microorganisms and Pollutants
The microorganisms present in the rhizosphere soil can transform the pollutants
from one oxidation state to another. Microbes protect its own structure from metal
toxicity through various mechanisms, namely oxidation, reduction, methylation,
adsorption, etc. Methylation is an important method that play important role in
bioremediation. For example, mercury, bioethylated by a number of bacterial species, namely Alcaligenes faecalis, Bacillus pumilus, Bacillus sp., P. aeruginosa and
Brevibacterium iodinium to gaseous methyl mercury. Environmental factors also
play an important role for the growth and activity of microbes to enhance bioremediation (Vidali 2001). The long-term application of pesticides can also promote
biodegrading enzymes in the indigenous microflora, as they serve as a source of
carbon and energy, making the remediation of pesticide contaminated sites easier
(Qiu et al. 2009).
1.8.1 Degradation of Pesticides by Rhizospheric Microbes
Rhizospheric microorganisms are universal scavengers for decaying or recycling the
waste materials into harmless things. It includes bacteria, fungi and actinomycetes
which are able to eliminate the pesticides from the environment (Parte et al. 2017).
Many researchers reported that soil microorganisms such as Burkholderia,
Arthobacter, Aztobacter and Flavobacterium degraded the pesticides (Shi and
Bending 2007). Single microbe can degrade more than one herbicide and pesticide
and also involved in plant growth promotion and zinc and phosphorus solubilization.
Staphylococcus sp. and Bacillus circulans isolated from the surrounding area of
pesticide production industry degraded 72–76% of endosulfan under aerobic and
facultative anaerobic conditions (Kumar and Philip 2007). In the chemical industry,
various chlorinated compounds are used as the industrial solvents and degraded by
Aminobacter and Mesorhizobium sp. by the secretion of enzymes (Osborn et al.
2010). Organophosphorus pesticides were degraded extensively (Singh 2008).
1 Rhizosphere: Niche for Microbial Rejuvenation and Biodegradation of Pollutants
11