Tezer (2005). Microbial consortium which could degrade azo dye was obtained from
a wastewater treatment plant in Taiwan and immobilized in phosphorylated PVA gel
beads (Chen et al. 2003). A very few studies are available on response surface
methodology (RSM) for optimization of various physicochemical parameters by
algae. Neural network modeling of biotreatment of triphenylmethane dye solution by
a green macroalgae by Khataee et al. (2011) is very important study for checking the
bisorption potential of algae.
3.2 Degradation of Pesticides
In effort to enhance food production to meet the growing human population, the use
of pesticide in agriculture is on increased nowadays. The use of this pesticide
released toxic substances that are hazardous to man. Pesticides can also
bioaccumulate or biomagnify and cause danger to the environment (Ragini and
Bisen 2011). Several cyanobacterial species were revealed to be capable of reducing
the toxicity of this hazardous substance. Lindane, a highly chlorinated aliphatic
pesticide, was found to be degraded by two filamentous cyanobacteria Anabaena
sp. PCC 7120 and Nostoc ellipsosporum strain B1453–7 (Kuritz and Wolk 1995).
The same species was also found by Kuritz (1998) to degrade the same pollutant,
first to pentachlorocyclohexane and then to trichlorobenzenes. Because the degradation occurred in the presence of nitrate and the process is inhibited by both
darkness and ammonia, the mechanism of degradation was proposed to be a nitrate
reduction system of cyanobacteria. Fenamiphos, an organophosphorus pesticide,
was also found to be degraded by five different cyanobacterial species (Ca
0 ceres
et al. 2008). These species are Anabaena sp., Nostoc muscorum, Nostoc sp. MMI,
Nostoc sp. MM2, and Nostoc sp. MM3. The degradation of this pollutant was found
to be through hydrolysis and oxidation. The products of oxidation were toxic, while
hydrolysis was referred to be detoxification.
Pesticide degradation process involves three phases. Phase I involves hydrolysis,
oxidation, or reduction. This phase converts the pesticides into less toxic and watersoluble substances. Phase II involves the binding of pesticide metabolites or pesticides to the sugar, glutathione, or amino acids. Toxicity is reduced, and solubility is
increased in this phase compared to phase I. Phase III involves the conversion of
metabolites of phase II to form nontoxic substances (Hatzios 1991; Shimabukuros
1985). Because of the complexity and toxicity of pesticides, organisms must possess
certain features to be able to degrade them to nontoxic substances. According to
Ragini and Bisen (2011), organisms can possess the ability to degrade pesticide via
adaptive enzymes that can be induced in the presence of pesticides. The constitutive
enzymes may be induced by the adapted organisms in the polluted environment
before degrading pesticide via random mutation.
16 Cyanobacteria: The Eco-Friendly Tool for the Treatment of Industrial Wastewaters
401
a wastewater treatment plant in Taiwan and immobilized in phosphorylated PVA gel
beads (Chen et al. 2003). A very few studies are available on response surface
methodology (RSM) for optimization of various physicochemical parameters by
algae. Neural network modeling of biotreatment of triphenylmethane dye solution by
a green macroalgae by Khataee et al. (2011) is very important study for checking the
bisorption potential of algae.
3.2 Degradation of Pesticides
In effort to enhance food production to meet the growing human population, the use
of pesticide in agriculture is on increased nowadays. The use of this pesticide
released toxic substances that are hazardous to man. Pesticides can also
bioaccumulate or biomagnify and cause danger to the environment (Ragini and
Bisen 2011). Several cyanobacterial species were revealed to be capable of reducing
the toxicity of this hazardous substance. Lindane, a highly chlorinated aliphatic
pesticide, was found to be degraded by two filamentous cyanobacteria Anabaena
sp. PCC 7120 and Nostoc ellipsosporum strain B1453–7 (Kuritz and Wolk 1995).
The same species was also found by Kuritz (1998) to degrade the same pollutant,
first to pentachlorocyclohexane and then to trichlorobenzenes. Because the degradation occurred in the presence of nitrate and the process is inhibited by both
darkness and ammonia, the mechanism of degradation was proposed to be a nitrate
reduction system of cyanobacteria. Fenamiphos, an organophosphorus pesticide,
was also found to be degraded by five different cyanobacterial species (Ca
0 ceres
et al. 2008). These species are Anabaena sp., Nostoc muscorum, Nostoc sp. MMI,
Nostoc sp. MM2, and Nostoc sp. MM3. The degradation of this pollutant was found
to be through hydrolysis and oxidation. The products of oxidation were toxic, while
hydrolysis was referred to be detoxification.
Pesticide degradation process involves three phases. Phase I involves hydrolysis,
oxidation, or reduction. This phase converts the pesticides into less toxic and watersoluble substances. Phase II involves the binding of pesticide metabolites or pesticides to the sugar, glutathione, or amino acids. Toxicity is reduced, and solubility is
increased in this phase compared to phase I. Phase III involves the conversion of
metabolites of phase II to form nontoxic substances (Hatzios 1991; Shimabukuros
1985). Because of the complexity and toxicity of pesticides, organisms must possess
certain features to be able to degrade them to nontoxic substances. According to
Ragini and Bisen (2011), organisms can possess the ability to degrade pesticide via
adaptive enzymes that can be induced in the presence of pesticides. The constitutive
enzymes may be induced by the adapted organisms in the polluted environment
before degrading pesticide via random mutation.
16 Cyanobacteria: The Eco-Friendly Tool for the Treatment of Industrial Wastewaters
401