high molecular weight into soluble fractions, which are easily transferred by the cell
wall for the process of assimilation. There are only particular species of microbes
that have proved to be potential organisms that can convert specific substrates and
can be grown under laboratory conditions as effective agents of bioremediation (Fan
and Krishnamurthy 1995; Karigar and Rao 2011). The following are the microbes
based on different categories discussed as per findings till now which are been
utilized for the process of bioremediation.
15.4.1 Bacteria
Bacteria are the category of microbes which are easily obtained by the method which
does not depend on additional clean up and are actively involved in biodegradation
of organic pollutants (which serves as food to it) from polluted places (Haritash and
Kaushik 2009; Agwu and Kalu 2012). Thus, this technique is a self-clearing process
that ensures environmental sustainability. The use of bacteria in clearing up of soil
contaminated with explosives, petroleum and hazardous wastes, sewage chlorinated
solvents, pesticides and agricultural chemicals has been stated by many scientists
(Agwu and Kalu 2012). Bacteria based on their oxygen uptake can be categorized
into the following:
Aerobic Bacteria: Aerobic bacteria have been recognized for their degradative
abilities that are isolated and primarily focus on Gram-negative bacterial strains
that belong to the genera such as Burkholderia, Ralstonia, Achromobacter,
Alcaligenes, Comamonas, Rhodococcus, Pseudomonas, Sphingomonas and
Mycobacterium, which is usually reported for biodegradation of pesticides and
hydrocarbons (alkanes as well as polyaromatic hydrocarbons, PAHs).
Anaerobic Bacteria: Aerobic bacteria are more often utilized as compared to anaerobic bacteria. Anaerobic bacteria are being used for the process of biodegradation
of polychlorinated biphenyls (PCBs), which are subjected to reductive
dehalogenation in the sediments of the river; dechlorination of solvents such as
trichloroethylene (TCE) and chloroform is gaining the interest of the researchers
(Kumar et al. 2011).
Apart from anaerobic bacteria, many other strains of bacteria are also potentially
capable of oxidation of PCBs into simpler compounds such as Pseudomonas,
Burkholderia, Comamonas and Rhodococcus sp. (Jing et al. 2018). Bacteria are
not only the most effective mode for degradation of petroleum but also primary
degraders of spilled oil (Das and Chandran 2011). Bacteria that are capable of
bioremediation of petroleum products include Bacillus sp., Aeromonas, Moraxella,
Beijerinckia, Flavobacteria, Chrobacteria, Nocardia, Corynebacterium sp.,
Modococci, Streptomyces, Arthrobacter, and Aeromonas. Pseudomonas
fluorescens, P. aeruginosa, B. subtilis, Alcaligenes sp., Acinetobacter lwoffi,
Flavobacterium sp., Micrococcus roseus were isolated from the contaminated
stream that biodegrades the crude form of oil (Das and Chandran 2011; Joutey
432
G. Kaur et al.
wall for the process of assimilation. There are only particular species of microbes
that have proved to be potential organisms that can convert specific substrates and
can be grown under laboratory conditions as effective agents of bioremediation (Fan
and Krishnamurthy 1995; Karigar and Rao 2011). The following are the microbes
based on different categories discussed as per findings till now which are been
utilized for the process of bioremediation.
15.4.1 Bacteria
Bacteria are the category of microbes which are easily obtained by the method which
does not depend on additional clean up and are actively involved in biodegradation
of organic pollutants (which serves as food to it) from polluted places (Haritash and
Kaushik 2009; Agwu and Kalu 2012). Thus, this technique is a self-clearing process
that ensures environmental sustainability. The use of bacteria in clearing up of soil
contaminated with explosives, petroleum and hazardous wastes, sewage chlorinated
solvents, pesticides and agricultural chemicals has been stated by many scientists
(Agwu and Kalu 2012). Bacteria based on their oxygen uptake can be categorized
into the following:
Aerobic Bacteria: Aerobic bacteria have been recognized for their degradative
abilities that are isolated and primarily focus on Gram-negative bacterial strains
that belong to the genera such as Burkholderia, Ralstonia, Achromobacter,
Alcaligenes, Comamonas, Rhodococcus, Pseudomonas, Sphingomonas and
Mycobacterium, which is usually reported for biodegradation of pesticides and
hydrocarbons (alkanes as well as polyaromatic hydrocarbons, PAHs).
Anaerobic Bacteria: Aerobic bacteria are more often utilized as compared to anaerobic bacteria. Anaerobic bacteria are being used for the process of biodegradation
of polychlorinated biphenyls (PCBs), which are subjected to reductive
dehalogenation in the sediments of the river; dechlorination of solvents such as
trichloroethylene (TCE) and chloroform is gaining the interest of the researchers
(Kumar et al. 2011).
Apart from anaerobic bacteria, many other strains of bacteria are also potentially
capable of oxidation of PCBs into simpler compounds such as Pseudomonas,
Burkholderia, Comamonas and Rhodococcus sp. (Jing et al. 2018). Bacteria are
not only the most effective mode for degradation of petroleum but also primary
degraders of spilled oil (Das and Chandran 2011). Bacteria that are capable of
bioremediation of petroleum products include Bacillus sp., Aeromonas, Moraxella,
Beijerinckia, Flavobacteria, Chrobacteria, Nocardia, Corynebacterium sp.,
Modococci, Streptomyces, Arthrobacter, and Aeromonas. Pseudomonas
fluorescens, P. aeruginosa, B. subtilis, Alcaligenes sp., Acinetobacter lwoffi,
Flavobacterium sp., Micrococcus roseus were isolated from the contaminated
stream that biodegrades the crude form of oil (Das and Chandran 2011; Joutey
432
G. Kaur et al.