nutrition modes displayed by cyanobacteria for acquiring carbon or nutrients help to
extend their niche opportunities in changing environments. Depending on the
species, their physiology, cell size, and biotic and abiotic environmental growth
conditions, they can use various forms of nitrogen (elemental nitrogen, ammonium,
nitrate, organic nitrogen) or particulate organic substances for growth (Raven 1997;
Graneli et al. 1999).
Furthermore, cyanobacteria have the capability to oxidize the pollutants such as
oils, pesticides, and dyes and produce peptides that are able to bind heavy metals
(Wide and Bennan 1993). They are attractive bio-agent for the bioremediation of
pollutants. The mixed culture of cyanobacteria, containing various species with
different metabolic abilities may improve the overall remediation capacity of cultures when supplemented with multiple resources. Cyanobacteria have wide variety
of metabolisms and are growing in all habitats even in extreme environments (high
temperature and alkaline environment). In natural aquatic environments,
cyanobacteria are associated with strong heterotrophic bacteria. This suggests a
close interaction between the various microbial communities. However, very little
information is known about the nature of such associations (independence, competition, mutualism, or symbiosis) which is still debated (Fouill and Mostajir 2011).
Cyanobacteria have high genetic and metabolic variability and high biomass
productivity. They play an important role as primary producers in these ecosystems
(Oren and Seckbach 2001). Recent studies reported large genetic diversity among
cultured cyanobacteria within and between aquatic environments. This genetic
diversity is not represented well by traditional morphological microscopic identifications of cyanobacteria. To date, the majority of information on genetic diversity of
cyanobacteria in lakes is based on analyses of cultured cyanobacteria. Janse et al.
(2004) isolated 107 cyanobacteria from 15 lakes and found 59 distinct genotypes.
Altogether, these studies suggest that populations of cyanobacteria are heterogeneous both within and across aquatic environments.
2.2 Benefits of Cyanobacteria in Bioremediation
In recent years, cyanobacteria attracted considerable scientific and technical interest
for biological treatment of polluted wastewater. Because cyanobacteria have a great
potential for the treatment of various types of environmental contaminants such as
pesticides (Megharaj et al. 1994), crude oil (Al-Hasan and Radwan 2001), phenol
(Shashirekha et al. 1997), heavy metals (Singh et al. 2011), textile dyes (Mona et al.
2011), and xenobiotics (Megharaj et al. 1987). They have high growth rate and metal
sorption capacity that play a potential role in the detoxification of various industrial
effluents such as from oil refinery, pulp and paper, brewery, distilleries, tanneries,
textile, dye, and pharmaceuticals industries.
There are several advantages of cyanobacteria that are used as a biological agent
for the bioremediation of wastewater. Cyanobacteria have advantages over chemical
treatment as they are widespread in all conceivable system and also able to
16 Cyanobacteria: The Eco-Friendly Tool for the Treatment of Industrial Wastewaters
393
extend their niche opportunities in changing environments. Depending on the
species, their physiology, cell size, and biotic and abiotic environmental growth
conditions, they can use various forms of nitrogen (elemental nitrogen, ammonium,
nitrate, organic nitrogen) or particulate organic substances for growth (Raven 1997;
Graneli et al. 1999).
Furthermore, cyanobacteria have the capability to oxidize the pollutants such as
oils, pesticides, and dyes and produce peptides that are able to bind heavy metals
(Wide and Bennan 1993). They are attractive bio-agent for the bioremediation of
pollutants. The mixed culture of cyanobacteria, containing various species with
different metabolic abilities may improve the overall remediation capacity of cultures when supplemented with multiple resources. Cyanobacteria have wide variety
of metabolisms and are growing in all habitats even in extreme environments (high
temperature and alkaline environment). In natural aquatic environments,
cyanobacteria are associated with strong heterotrophic bacteria. This suggests a
close interaction between the various microbial communities. However, very little
information is known about the nature of such associations (independence, competition, mutualism, or symbiosis) which is still debated (Fouill and Mostajir 2011).
Cyanobacteria have high genetic and metabolic variability and high biomass
productivity. They play an important role as primary producers in these ecosystems
(Oren and Seckbach 2001). Recent studies reported large genetic diversity among
cultured cyanobacteria within and between aquatic environments. This genetic
diversity is not represented well by traditional morphological microscopic identifications of cyanobacteria. To date, the majority of information on genetic diversity of
cyanobacteria in lakes is based on analyses of cultured cyanobacteria. Janse et al.
(2004) isolated 107 cyanobacteria from 15 lakes and found 59 distinct genotypes.
Altogether, these studies suggest that populations of cyanobacteria are heterogeneous both within and across aquatic environments.
2.2 Benefits of Cyanobacteria in Bioremediation
In recent years, cyanobacteria attracted considerable scientific and technical interest
for biological treatment of polluted wastewater. Because cyanobacteria have a great
potential for the treatment of various types of environmental contaminants such as
pesticides (Megharaj et al. 1994), crude oil (Al-Hasan and Radwan 2001), phenol
(Shashirekha et al. 1997), heavy metals (Singh et al. 2011), textile dyes (Mona et al.
2011), and xenobiotics (Megharaj et al. 1987). They have high growth rate and metal
sorption capacity that play a potential role in the detoxification of various industrial
effluents such as from oil refinery, pulp and paper, brewery, distilleries, tanneries,
textile, dye, and pharmaceuticals industries.
There are several advantages of cyanobacteria that are used as a biological agent
for the bioremediation of wastewater. Cyanobacteria have advantages over chemical
treatment as they are widespread in all conceivable system and also able to
16 Cyanobacteria: The Eco-Friendly Tool for the Treatment of Industrial Wastewaters
393