response to the oil spill with much decreased cost is a combination of physical,
chemical, and biological treatments. Recently, Villela et al. (2019) have reported an
analysis of the patent documents in bioremediation, which use microorganisms to
clean seawater. According to their report, China, Russia, and USA have various
temporal deposit profiles dictated by their historical, political, and economic regulations. In their list of countries, which have patent applications, China has the first
place with 152 deposits followed by Russia with 133 and then USA with 48. Among
500 patent documents considered in this study, 368 patents presented a description
of oil degradation exclusively by bacteria, 24 by yeasts and fungi, 32 by mixed
consortia, 1 using a microalgal strain, and 1 by archaea. The major microbial genera
are Pseudomonas with 114 patents, Bacillus with 75, and Rhodococcus with 60.
Metabolic Processes of Bioremediation
The first level of the organic compound metabolism is use of the substrate, which
serves as an electron donor for microbial growth and acts as a source of energy and
carbon. When the nature of the molecular structure, which induces the essential
catabolic enzymes, cannot provide the energy and carbon, co-metabolism to sitetreatment of xenobiotics is required to be applied. The term co-metabolism refers to
the metabolism of a material that cannot act as a source of energy, carbon, and
essential nutrient. The essential nutrients are provided only in the presence of a
primary (enzyme inducing) material (Boopathy 2000). The term aerobic process
refers to the metabolic activities involving oxygen as a reactant. The two primary
enzymes employed during mineralization and transformation of xenobiotics by
aerobic organisms are dioxygenases and monooxygenases. Aerobic bacteria like
Alcaligenes, Pseudomonas, Mycobacterium, Sphingomonas, and Rhodococcus have
ability to treat pollutants. These microbes degrade hydrocarbons including alkanes
and polycyclic aromatic compounds as well as pesticides. When an activity of an
organism involves other molecules besides oxygen, the process is anaerobic. Anaerobic microbes apply electron acceptors like iron, nitrate, manganese, carbon dioxide
and sulfate based on their availability and the dominant redox conditions. Use of
anaerobic bacteria for biotreatment of polychlorinated biphenyls in sediments of
river, dechlorination of the solvent chloroform, and trichloroethylene has been
attracting much interest (Lovley 1995). In conclusion it can be said that the
oxidation–reduction reactions play important role in bioremediation.
The Classes of Bioremediation
Bioremediation techniques are divided into two classes: in situ and ex situ. In ex situ
technology, the treatments involve the physical removal of the polluted materials
from contaminated site and transporting them to another site (Azubuike et al. 2016),
while in situ technology is involved with treatment of the polluted materials at the
site of contamination (Boopathy 2000). Therefore, excavation and its extra cost are
12 Remediation of Pollution by Oil Spills
467
chemical, and biological treatments. Recently, Villela et al. (2019) have reported an
analysis of the patent documents in bioremediation, which use microorganisms to
clean seawater. According to their report, China, Russia, and USA have various
temporal deposit profiles dictated by their historical, political, and economic regulations. In their list of countries, which have patent applications, China has the first
place with 152 deposits followed by Russia with 133 and then USA with 48. Among
500 patent documents considered in this study, 368 patents presented a description
of oil degradation exclusively by bacteria, 24 by yeasts and fungi, 32 by mixed
consortia, 1 using a microalgal strain, and 1 by archaea. The major microbial genera
are Pseudomonas with 114 patents, Bacillus with 75, and Rhodococcus with 60.
Metabolic Processes of Bioremediation
The first level of the organic compound metabolism is use of the substrate, which
serves as an electron donor for microbial growth and acts as a source of energy and
carbon. When the nature of the molecular structure, which induces the essential
catabolic enzymes, cannot provide the energy and carbon, co-metabolism to sitetreatment of xenobiotics is required to be applied. The term co-metabolism refers to
the metabolism of a material that cannot act as a source of energy, carbon, and
essential nutrient. The essential nutrients are provided only in the presence of a
primary (enzyme inducing) material (Boopathy 2000). The term aerobic process
refers to the metabolic activities involving oxygen as a reactant. The two primary
enzymes employed during mineralization and transformation of xenobiotics by
aerobic organisms are dioxygenases and monooxygenases. Aerobic bacteria like
Alcaligenes, Pseudomonas, Mycobacterium, Sphingomonas, and Rhodococcus have
ability to treat pollutants. These microbes degrade hydrocarbons including alkanes
and polycyclic aromatic compounds as well as pesticides. When an activity of an
organism involves other molecules besides oxygen, the process is anaerobic. Anaerobic microbes apply electron acceptors like iron, nitrate, manganese, carbon dioxide
and sulfate based on their availability and the dominant redox conditions. Use of
anaerobic bacteria for biotreatment of polychlorinated biphenyls in sediments of
river, dechlorination of the solvent chloroform, and trichloroethylene has been
attracting much interest (Lovley 1995). In conclusion it can be said that the
oxidation–reduction reactions play important role in bioremediation.
The Classes of Bioremediation
Bioremediation techniques are divided into two classes: in situ and ex situ. In ex situ
technology, the treatments involve the physical removal of the polluted materials
from contaminated site and transporting them to another site (Azubuike et al. 2016),
while in situ technology is involved with treatment of the polluted materials at the
site of contamination (Boopathy 2000). Therefore, excavation and its extra cost are
12 Remediation of Pollution by Oil Spills
467