products even in the presence of 30% sodium chloride. An extremely halophilic
Archaea Haloferax mediterranei was isolated and found to grow at 10–25% sodium
chloride (Zvyagintseva et al. 1995). Kulichevskaya et al. (1992) isolated some
species the bacteria from Halobacterium group from salt-rich stratum fluids of an
oil deposit which degraded n-alkanes with a C10–C30 composition in the presence
of 30% (w/v) sodium chloride. The bacterium Alcanivorax dieselolei strain B-5,
isolated from surface water of the Bohai Sea, produces different alkane hydroxylase
extremozymes which degrade either chlorinated or brominated alkanes with different chain lengths, thus displaying potential for biodegradation and other industrial
applications (Li and Shao 2014). Others haloarchaeas from the genus Haloferax are
able to degrade a mixture of PAHs (anthracene, naphthalene, phenanthrene, pyrene)
in hypersaline medium (Bonfa et al. 2011).
The archaea Natrialba sp. C21 isolated from oil-contaminated saline water in Ain
Salah (Algeria) was able to survive under high salt concentrations (25%) solution
containing aromatic hydrocarbons (Khemili-Talbi et al. 2015). This strain demonstrated good potential for degrading pyrene (3% v/v) and naphthalene (3% v/v) after
7 days at 40
C, pH 7.0 and high salinity conditions. Zhao et al. (2017) reported an
strain of the haloarchaea 1M1011 isolated from Changlu Tanggu saltern near Da
Gang Oil field in Tianjin (China) by enrichment culture in hypersaline medium
containing hexadecane was able to degrade 57% of hexadecane (5 g L
À1 ) in the
presence of 3.6 M NaCl within 24 days at 37
C. An extremophilic microorganism
Stenotrophomonas maltophilia strain AJH1 isolated from a mineral mining site in
Saudi Arabia was able to degrade both HMW (pyrene) and LMW (anthracene,
naphthalene) in acidophilic mineral salt medium at pH 2 (Arulazhagan et al.
2017). Three haloalkaliphilic Pseudomonas strains (HA10, HA12 and HA14) were
studied by Hassan and Aly (2018) and reported to degrade BTEX (benzene, toluene,
ethylbenzene and xylene) at pH 9 in the presence of NaCl (7% w/v). Three novel
catechol 2,3-dioxynease genes, namely C23010, C23012 and C23014 were amplified, cloned and overexpressed from these strains.
In recent past few years, many studies applying extremophilic microorganisms in
hydrocarbon degradation were undertaken but toxicity evaluation during this process
are not considered. Hence, toxicity assays should be included to evaluate the
efficiency of the process in eliminating or reducing toxicity (Giovanlla et al. 2020).
12.5.2 Bioremediation of Chemical Pesticides
Chemical pesticides are any substance or mixture of substances intended for
preventing, destroying, repelling or mitigating any insects, weeds and plant pathogens. Pesticides are widely used worldwide to control agricultural and household
pests. The most commonly used pesticides belong to the organophosphorus group,
and the first organophosphorus insecticide, tetraethyl pyrophosphate, was developed
12 Potential of Extremophiles for Bioremediation
309
Archaea Haloferax mediterranei was isolated and found to grow at 10–25% sodium
chloride (Zvyagintseva et al. 1995). Kulichevskaya et al. (1992) isolated some
species the bacteria from Halobacterium group from salt-rich stratum fluids of an
oil deposit which degraded n-alkanes with a C10–C30 composition in the presence
of 30% (w/v) sodium chloride. The bacterium Alcanivorax dieselolei strain B-5,
isolated from surface water of the Bohai Sea, produces different alkane hydroxylase
extremozymes which degrade either chlorinated or brominated alkanes with different chain lengths, thus displaying potential for biodegradation and other industrial
applications (Li and Shao 2014). Others haloarchaeas from the genus Haloferax are
able to degrade a mixture of PAHs (anthracene, naphthalene, phenanthrene, pyrene)
in hypersaline medium (Bonfa et al. 2011).
The archaea Natrialba sp. C21 isolated from oil-contaminated saline water in Ain
Salah (Algeria) was able to survive under high salt concentrations (25%) solution
containing aromatic hydrocarbons (Khemili-Talbi et al. 2015). This strain demonstrated good potential for degrading pyrene (3% v/v) and naphthalene (3% v/v) after
7 days at 40
C, pH 7.0 and high salinity conditions. Zhao et al. (2017) reported an
strain of the haloarchaea 1M1011 isolated from Changlu Tanggu saltern near Da
Gang Oil field in Tianjin (China) by enrichment culture in hypersaline medium
containing hexadecane was able to degrade 57% of hexadecane (5 g L
À1 ) in the
presence of 3.6 M NaCl within 24 days at 37
C. An extremophilic microorganism
Stenotrophomonas maltophilia strain AJH1 isolated from a mineral mining site in
Saudi Arabia was able to degrade both HMW (pyrene) and LMW (anthracene,
naphthalene) in acidophilic mineral salt medium at pH 2 (Arulazhagan et al.
2017). Three haloalkaliphilic Pseudomonas strains (HA10, HA12 and HA14) were
studied by Hassan and Aly (2018) and reported to degrade BTEX (benzene, toluene,
ethylbenzene and xylene) at pH 9 in the presence of NaCl (7% w/v). Three novel
catechol 2,3-dioxynease genes, namely C23010, C23012 and C23014 were amplified, cloned and overexpressed from these strains.
In recent past few years, many studies applying extremophilic microorganisms in
hydrocarbon degradation were undertaken but toxicity evaluation during this process
are not considered. Hence, toxicity assays should be included to evaluate the
efficiency of the process in eliminating or reducing toxicity (Giovanlla et al. 2020).
12.5.2 Bioremediation of Chemical Pesticides
Chemical pesticides are any substance or mixture of substances intended for
preventing, destroying, repelling or mitigating any insects, weeds and plant pathogens. Pesticides are widely used worldwide to control agricultural and household
pests. The most commonly used pesticides belong to the organophosphorus group,
and the first organophosphorus insecticide, tetraethyl pyrophosphate, was developed
12 Potential of Extremophiles for Bioremediation
309