The cyanobacteria or blue-green algae (BGA) are the group of microorganisms having an oxygen-evolving photosynthetic system. Many genera are aerobic nitrogen-fixers and some others also are known to grow on molecular nitrogen in the anaerobic and symbiotic state. The combination of an oxygen-evolving photosynthesis with the oxygen-sensitive nitrogen-fixing system is rare among the microbes. In addition, they have the ability to invade otherwise uninhabitable sections of the environment, namely, hot springs, icelands, volcanic soil, and sewage wherein the combined-nitrogen content either is absent or the temperature is in either of the extremes or a variety of natural or artificial chemicals is present. The cyanobacteria have a role in binding the soil particles and also add nitrogenous compounds to the soil. The global combined nitrogen of cyanobacteria both free-living and symbiotic forms (Azolla, Cycas, etc.) is important today when we think of the protein demand of the developing countries tomorrow. Thus, study of the abundance of cyanobacteria in natural ecosystems and rice fields (where they grow mostly in tropical climates) is important.
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- Cyanobacteria and pesticides
Rabindra N. Padhy
- Springer New York