2012). For the purpose of bioremediation, new culture-independent applications
obtain assistance of sequencing as well as in silico strategies for screening of both
sequence as well as function-dependent genes (Khan et al. 2013). By knowing the
physico-chemical parameters of the environmental conditions, the environmental
DNA and functional RNA can be manipulated additionally to devise the species
relations in a community structure. Actually, the complex nature and variation in
biological organization at various stages is known as microbial diversity which
incorporates the magnitude and allocation of genetic information within microbial
species in microbial communities, their difference in community structure,
complications associated with interactions, number of trophic levels and number
of guilds (Hinojosa et al. 2010). Microbes consist of de novo capability for
decomposing all naturally occurring compounds by the principle of microbial
infallibility (Dash et al. 2013). Microorganisms degrade organic contaminants
through oxidizing them to carbon dioxide, while for toxic metals, microorganisms
can only change the species of metal and their mobility (Lovley and Coates 1997).
Presently, microbial diversity with metabolic capacity partially has been searched,
and further use of the unnoticed genetic resources will increase the remediation
practices of toxic metals (Naser 2013). Additionally, newly developed molecular
genetics of bioremediation and knowledge-based strategies of balanced protein
modification will give more light in the production designer biocatalysts for environmental bioremediation (Pieper and Reineke 2000; Paul et al. 2005; Das et al.
2016).
12.4 Utilization of the Natural Biodiversity
12.4.1 Microbial Remediation of Heavy Metals Polluted Soils
Many bacteria such as Bacillus subtilis, Pseudomonas putida, and Enterobacter
cloacae are employed effectively for decreasing high toxicity of chromium into the
less toxic Cr (VI–III) (Ajmal et al. 1996). Bacillus thuringiensis has removed more
Cd and Zn from soil polluted with Cd as well as the effluent of the metal industry. It
is thought that siderophore (Fe-complexing molecules) are produced by bacteria
which may be responsible for the removal of these metals from the soil which
ultimately affects their bioavailability (Khan 2005). Sulphate-reducing bacteria
like Desulfovibrio desulfuricans indirectly bioremediate by bioprecipitation which
changes sulphate to hydrogen sulphate and ultimately combines with heavy metals
such as Cd and Zn to form insoluble metal sulphides. There is a lot of debate
concerning genetically modified organisms and also the reality that the heavy
metal remains in the soil in this strategy of bioremediation which are prime
restrictions in implementation. One approach in bioremediating polluted soils is to
make the soil favourable for soil microbes. This is known as biostimulation in which
nutrients are added as manure or other organic amendments for carbon source to the
microorganisms present in the soil. These additional nutrients will boost the growth
and activities of microorganisms implicated in the remediation procedure and also
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obtain assistance of sequencing as well as in silico strategies for screening of both
sequence as well as function-dependent genes (Khan et al. 2013). By knowing the
physico-chemical parameters of the environmental conditions, the environmental
DNA and functional RNA can be manipulated additionally to devise the species
relations in a community structure. Actually, the complex nature and variation in
biological organization at various stages is known as microbial diversity which
incorporates the magnitude and allocation of genetic information within microbial
species in microbial communities, their difference in community structure,
complications associated with interactions, number of trophic levels and number
of guilds (Hinojosa et al. 2010). Microbes consist of de novo capability for
decomposing all naturally occurring compounds by the principle of microbial
infallibility (Dash et al. 2013). Microorganisms degrade organic contaminants
through oxidizing them to carbon dioxide, while for toxic metals, microorganisms
can only change the species of metal and their mobility (Lovley and Coates 1997).
Presently, microbial diversity with metabolic capacity partially has been searched,
and further use of the unnoticed genetic resources will increase the remediation
practices of toxic metals (Naser 2013). Additionally, newly developed molecular
genetics of bioremediation and knowledge-based strategies of balanced protein
modification will give more light in the production designer biocatalysts for environmental bioremediation (Pieper and Reineke 2000; Paul et al. 2005; Das et al.
2016).
12.4 Utilization of the Natural Biodiversity
12.4.1 Microbial Remediation of Heavy Metals Polluted Soils
Many bacteria such as Bacillus subtilis, Pseudomonas putida, and Enterobacter
cloacae are employed effectively for decreasing high toxicity of chromium into the
less toxic Cr (VI–III) (Ajmal et al. 1996). Bacillus thuringiensis has removed more
Cd and Zn from soil polluted with Cd as well as the effluent of the metal industry. It
is thought that siderophore (Fe-complexing molecules) are produced by bacteria
which may be responsible for the removal of these metals from the soil which
ultimately affects their bioavailability (Khan 2005). Sulphate-reducing bacteria
like Desulfovibrio desulfuricans indirectly bioremediate by bioprecipitation which
changes sulphate to hydrogen sulphate and ultimately combines with heavy metals
such as Cd and Zn to form insoluble metal sulphides. There is a lot of debate
concerning genetically modified organisms and also the reality that the heavy
metal remains in the soil in this strategy of bioremediation which are prime
restrictions in implementation. One approach in bioremediating polluted soils is to
make the soil favourable for soil microbes. This is known as biostimulation in which
nutrients are added as manure or other organic amendments for carbon source to the
microorganisms present in the soil. These additional nutrients will boost the growth
and activities of microorganisms implicated in the remediation procedure and also
320
N. Srivastava