Many chemicals are released into surface water either as a method of disposal or as a consequence of the technology of the utilization. In particular, the use of pesticide many of which are toxic or contain toxic contaminants, is central to high yields of modern agriculture. Lindane is a toxic compound with potential long term persistence (Meister 1993 ; Alexander 1994). Anabaena sp.PCC71208 and Nostoc ellip-sosporum co-metabolise lindane. Stimulation of the rate of degradation of lindane by nitrate may be attributable to increased availability of nitrogen to nitrate supplemented culture. Fleming and Haselkorn (1974) found that atleast eight protein molecules were synthesised by nitrate-grown culture of Anabaena sp. strain PCC 7120 that were not derived from nitrate nitrogen growing cultures. Alternatively, same proteins were involved in the transport or metabolism of lindane. Anabaena sp. strain
PCC 7120 and N. ellipsosporum supplied with fcb ABC operon from Arthrobacter flobiformii (Tsoi et al. 1991) developed the capacity to dechlorinate 4CB; higher concentration of 4CB (2.5 mM) exhibited growth of the culture. Also, genetic engineering by addition of linA gene enhanced the degradation of lindane by two cyanobacterial strains at least when they were grown with nitrogen. It appears likely that other biodegradable operon will also be expressed in cyanobacteria. Cyanobacteria have been shown to degrade both naturally occurring aromatic hydrocarbons (Eillis 1977; Cerniglia and Gibson 1979; Cerniglia et al. 1980a, b; Narro et al. 1992) and xenobiotics (Meghraj et al. 1987) Wolk et al. (1995) have reported that cyanobacteria can be genetically engineered to enhance the degradation of organic pollutants such as highly chlorinated aliphatic pesticide , lindane (g-hexachloro cyclohexane) Oscillatoria sps. could tolerate upto 500 mg/l endosulfan.
Cyanobacteria metabolize organic compounds through ring hydroxtlation. This has been demonstrated in Aulosira fertilissima and Nostoc sp. which were able to degrade, detoxify and use the pesticide as the sole phosphorous source through the production of phosphate solubilizing enzyme (Subramanian et al. 1994). It was also found that cyanobacteria accelerated transformation and degradation of certain polycyclic aromatic hydrocarbons, organophosphorous compound in water by the sunlight. Thus algal detoxification of environmental pollutant could help in controlling the pollution of the aquatic and terrestrial habitat.
Salinity and temperature are important key environmental parameters that influence the degradative process of petroleum components. These parameters influence the structure and physiology of existing microbial communities and result in change in physical and chemical properties of pollutants (e.g. solubility and viscosity) including the diversity; the metabolic potential of degrading bacteria is considered to decrease as environmental conditions become more extreme (Foght and Mc Farlane 1999; Margesin and Schinner 2001). Earlier studies showed that the rate of hydrocarbon degradation decreased with increased salinity and biodegradation could not be detected above 15% salinity (Ward and Brock 1976; Rhykerd et al. 1995). Nevertheless bacterial strains capable of performing pollutant degradation at high salt concentration were isolated (Oren et al. 1992) . The increase in temperature was shown to enhance biodegradation (Ward and Brock 1976; Margesin and Schinner 2001), although high temperature is known to reduce the diversity of microbes.
Cyanobacterial mats develop well under extreme conditions where the abundance and activity of grazing organism is limited (Javor and Castenholz 1984; Cohen 1989; Farmer 1992) . These mats are of special interest because of the frequent exposure to oil pollution from nearby terminals. Indeed some of these mats became dominant only after the gulf war of 1991, when more than 10.8 million barrels of crude oil was released into the Arabian gulf (Sorkhoh et al. 1992; Fayad and Overton 1995).The cyanobacterium Microcoleus chloroplastes found in these mats was detected in many hyper saline environments (12%) (Prufert-Bebout and Garcia-Pichel 1994; Garica-Pichel et al. 1996; Karsten 1996) . The detection of relative sequences indicates that these mats contain bacterial population that is resistant to UV and solar radiation (Rainey et al. 1997). Salinity influences biodegradation rates either by reducing bacterial activity (Walker and Calwell 1975) or by limiting the solubility of hydrocarbons. This inhibitory effect of salinity was shown to be more pronounced for aromatic then for aliphatic compounds (Mille et al. 1991) .
Optimum temperature for degradation was 28°C which is close to ambient temperature. Degradation was possible at 40°C but not at 50°C nor below 15°C. The metabolism of polycyclic aromatic hydrocarbon degradation under thermophilic and mesophilic condition is shown to be different as a result of the influence of temperature on enzyme activity (Muller et al. 1998; Annweiler et al. 2000). Higher temperature also reduces the viscosity of crude oil and thus increases its diffusion through sediment, Raeid et al. (2006) showed that hypersaline polluted site could be enriched in oil degrading bacteria and that the addition of new bacteria was not needed. Therefore, attempt at the bioremediation of such sites should consider ways of stimulating existing bacteria to degrade oil compounds rather than introducing new strains.
Using marine cyanobacteria Oscillatoria sp. BDU10742 and Aphanocapsa sp. BDU 16 a halophilic bacterium Halobacterium D5101 Uma and Subramanian (1990) could treat Ossein factory effluents and reduce calcium and chloride levels significantly. This enabled 100% survival of Tilopia fish with cyanobacteria as the only feed. Shashirekha et al. (1997) found another marine cyanobacterium Pharmidium valderianum BDU 30501 that was able to tolerate and grow at a phenol concentration of 50 mg~ 1 and removed 38 mg.' with a retention period of 7 days. These results open the possibility of treating a variety of phenol containing effluents. The same organism was used to study the condition and regenerate optimal sorption/desorption of heavy metal ions cadmium and cobalt (Karna et al. 1999). Marine Oscillatoria boryana BDU92181 was found to effectively degrade and metabolize melanoidin, a pigment which is abundant in distillery effluents (Kalavathi et al 2001). Studies at National facility for marine cyanobacteria(NFMC) have identified suitable cyanobacteria for treating number of noxious effluent containing organophosphate pesticides, detergent, antibiotics etc. and even degradation of solid waste like coir pith by the lignolytic action of certain cyanobacteria (Malliga et al. 1996).
Some non-heterocystous cyanobacterium such as Oscillastoria, Microcoleus, Plectonema, Porphyrosiphon, Lyngbya and Trichodesmium have been reported to fix atmospheric nitrogen under anaerobic and micro aerobic conditions (Ohki et al. 1992; Tiwari et al. 2000) and they also produce a remarkable tolerance to the bio-cide viz., 2,4-D, Malathion and dimecron at doses higher than those recommended for rice crops (Table 34.1). Few strains of Anabaena could tolerate 100 ppm. ceresan M (N-Sulphanilideethylmercur-p-toulene) and sulphanilamide, while strain of Tolipothrix ternurs have been found to be sensitive up to a concentration of 0.1 ppm ceresan M (Venkatraman and Rajayalakshmi 1972). Effect of different concentration of malathion (10-200 ppmv/v) on the growth of chlorophyll a content of N.linkia and Westiellopsis sp. has been reported by Bastia and Adhikary (2001); lethal dose of the pesticide was 200 ppm(v/v).
Bioremediation offers many interesting avenues from a bioinformatics point of view although it is still little explored. This discipline requires the integration of organic compounds, sequence, structure and function of proteins, comparative
Table 34.1 Summary of the studies examining the response (s) of blue green algae to pesticides (Adhikary 2006)
SI No Organism
Insecticide/herbicide/ fungicide tested
1 Species of blue green algae
Cylindrospennum sp. Aulosira fertilissima Plectonema boryanum Nostoc muscorum
4 Nostoc muscorum Wollea bhardlvajae
5 Nostoc musorum
Mastigocladus laminosus Tolypothrix tenuis
Anabaena doliolum Nostoc muscorum
Anabaena ARM 286 Anabaena ARM 310
Ceresan, Dithane, Delapon
Hexachloro cyclo hexane (HCH)
Tolkan, Fluchloralin 50-500 ppm
0.1-100 ppm Most of the species of Anabaena tolerated
100 ppm of Ceresan. Dithane was lethal to some species of Anabaena and Nostoc even at the lowest concentrations. At 100 ppm of Delapon. Almost all species grew well. 10-500 ppm BHC was more toxic among all the pesticides tested. A fertilissima and P.boryanum were more resistant than Cylindrospennum sp. 25-1.000 (.ig/ml Higher concentration of the pesticide was more toxic at the acidic pH and the toxicity reduced at the alkaline pH 4-30 (.ig/ml Toxicity of both the insecticides could be removed 4 (.ig/ml by repeated cultivation of the alga
4 ppm Toxicity of HCH was reduced by increasing the concentration of the nutrients K,HP04 (10^10 ppm) andCaCI, (55-330"ppm) in the Culture medium M. laminosus tolerated both the pesticides up to 100 ppm. where as T. tenus tolerated Tolkan and Fluchloralin up to 500 and 50 ppm. respectively
2.5-20 ppm Anabaena doliolum was found to be more tolerant than either Nostoc muscorum or Anacystis nidulans to Butachlor; 1-10 ppm 10 ppm of BHC. was more stimulating for oxygen evolution.
Venkatraman and Rajayalakshmi (1972)
Kar and Singh (1977)
Kar and Singh (1979a) Kar and Singh (1979b)
Khalil et al. (1980)
Pandey and Kashyap
Subramaniam et al.
Anabaena variabilis Aulosirafertilissima Scytonema chiastum scytonema stuposum
10 Anabaena khannae Calothrix marchica Nostoc calcicola Tolypothrix limbata
11 25 species of rice field blue green algae
Benthiocarb Pandimethalin Oxadiazon Furadan (3%G)
12 Aulosira fertilissima Monocrotophos 1-250 ppm
ARM 68. Nostoc Malathion muscorum ARM 221 Dichlorovos
10 species heterocystous blue green algae
Sevin Rogor Hildan
Lethal effect was observed in Anabaena variabilis Dikshit and Tiwari at 100 ppm of Captan, 400 ppm of Cyathion, (1992)
in Aulosira fertilissima at 400 ppm of Dithane, 200 ppm Cyathion, chiastum at 100 ppm of Bavistin, 400 ppm of Cyathion and in Scytonema stuposum at 400 ppm of Bavistin, Beniate , Dithane and 200 ppm of Capton and Cyathion.
Anabaena khannae and Calothri marchica were Kolte and Goyal proved to be more resistant. (1992)
Among the Test organisms, all. the species Rath and Adhikary of Calothrix tolerated up to 70 mg/ml of (1994)
Furadon while Aulosira sp. was most sensitive. Sheathed forms of blue green algae were more tolerant.
The optimal concentration for growth Subramanian et al.
of monocrotophos, Malathion, Dichlorovos, (1994)
phosphomdon and Quinolphos was 100,75,25 and 1 ppm respectively. Both the species grew maximally with the pesticides in the absence of inorganic phosphate suggesting their utilization as the sole source of phosphorus.
Among the species tested. Calothrix parietina UU Das and Adhikary 1423 and. Calothrix sp. UU2427 possessing (1996)
a well defined sheath were more tolerant to all the three pestrcrdes.
genomics, and environmental microbiology and so on. Data related to bioremediation (genome sequence, structure of chemical compounds, enzymes sequence and structure etc.,) are being accumulated in public databases (Eillis et al. 2003).
The bioinformatics resume devoted to bioremediation is still scarce. The University of Minnesota Biocatalysis/Biodegradation database (UMBBD) is among the more prominent resource. Pazos et al. (2005) have developed Meta router, a system for maintaining heterogeneous information related to bioremedia-tion in a frame work that allows its query, administration and mining(application of methods for extracting new knowledge). Among the data mining features is a programme included for locating biodegradative pathways for chemical compounds, according to a given set of constraints and requirements. The interpretation of biodegradative information with the compounding protein and genome data provide a suitable framework for studying the global prospective of the bioreme-diation network. The full featured system (except administration facility) is freely available at http://pdg.cnb.uam.es/Metarouter. One of the reasons, our knowledge of microbial degradative pathways is so incomplete is the immense complexity of microbial physiology that allows response and adaptability to various internal and external stimuli (Fulekar 2007).
Bioinformatics provide database for microarrays, gene identification and microbial degradation pathways of compounds (Eillis et al. 2001). Bioinformatics analysis will facilitates and quicken the analysis of cellular process to understand the cellular mechanism to treat and control microbial cells as factories. Bioinformatics has wide application in bioremediation for the structure determination and pathways of biodegradation of xenobiotics (Fulekar and Sharma 2008).
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