Occurrence of copper resistant mutants in the toxic cyanobacteria Microcystis aeruginosa: characterisation and future implications in the use of copper sulphate as algaecide

• Published in: Water research (Oxford) Vol. 38; no. 8; pp. 2207 - 2213
• Main Authors: Garcı́a-Villada, Libertad, Rico, Marcos, Altamirano, Marı́a, Sánchez-Martı́n, Laura, López-Rodas, Victoria, Costas, Eduardo
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.2004; Elsevier Science
• Subjects: Air. Soil. Water. Waste. Feeding; Animal, plant and microbial ecology; Applied ecology; Applied sciences; Bacterial Toxins - chemistry; Biological and medical sciences; Copper - chemistry; Copper - pharmacology; Copper Sulfate - chemistry; Copper Sulfate - pharmacology; Copper sulphate; Cyanobacteria; Drug Resistance, Microbial; Ecotoxicology, biological effects of pollution; Environment. Living conditions; Eukaryota - drug effects; Eukaryota - growth & development; Exact sciences and technology; Fluctuation analysis; Fundamental and applied biological sciences. Psychology; Medical sciences; Microcystis - drug effects; Microcystis - growth & development; Microcystis aeruginosa; Mutation; Pollution; Public health. Hygiene; Public health. Hygiene-occupational medicine; Toxic cyanobacteria; Water Microbiology; Water Purification - instrumentation; Water Purification - methods; Water treatment and pollution; Copper sulphate; Microcystis aeruginosa; Mutation; Fluctuation analysis; Toxic cyanobacteria; Water treatment; Water supply; Sulfates; Long term; Modeling; Sulfur Compounds; Health and environment; Sensitivity resistance; Artificial lake; Cyanobacteria; Surface water; Bacteria; Population dynamics; Kinetics; Public health
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2004.01.036

Freshwater toxic cyanobacteria are an increasing problem to human and animal health. Control of cyanobacteria in water supply reservoirs involves the use of algaecides, such as copper sulphate, usually in a repetitive way. Repercussions of recurrent algaecide treatments on cyanobacteria population dynamics remain still unknown. We studied the adaptation of cyanobacteria to lethal doses of copper sulphate by using Microcystis aeruginosa as an experimental model. A fluctuation analysis demonstrated that copper-resistant cells arise by spontaneous mutations that occur randomly prior to exposition to copper sulphate. The rate of spontaneous mutation from copper sensitivity to resistance was 1.76×10 −6 mutants per cell division. Resistant mutants exhibited a diminished fitness in the absence of copper sulphate, but only these variants were able to grow at Cu 2+ concentrations higher than 5.8 μM. In addition, copper-resistant cells were significantly smaller than wild-type ones. Warnings on the long-term consequences of repetitive algaecide treatments in water supplies are suggested.