Effect of barium and nickel on the growth of Anacystis nidulans

Anacystis nidulans is a simple, unicellular, prokaryotic microorganism. Like other cyanobacteria it is an obligate photoautotroph that is similar to gram-negative bacteria in cell wall structure, replication, and ability to harbor plasmids. Cyanobacteria are excellent organisms to serve as models for the investigation of a wide variety of biological problems, including indicators of environmental pollution. There have been several studies on the effects of heavy metals on A. nidulans. Toxic metals are a major water pollution problem. Metals come from natural weathering processes of the earth's crust, but industrialization and urbanization have led to an increase in contamination of aquatic environments, mainly from industrial discharge, pest or disease control agents applied to plants, urban runoff, mining, soil erosion, sewage effluents, air pollution fallout, and other sources. Among these contaminants are nickel, barium, and their derivatives. Nickel is found in small quantities in the earth's crust (80ppm). Nickel smelting, nickel ore extraction, electronic electroplating, fossil fuels, incineration, coins, steel alloys, batteries and other sources all add to endangerment of the ecosystem by nickel pollution. Nickel carbonyl, formed by nickel in the presence of carbon monoxide, is the most toxic form of nickel. The binding capacity of waste biomass for silver, chromium, lead and copper was reported as greater than that for nickel. Some ions may also play a role as essential cofactors in metalloenzymes, as is the case for nickel.