Abstract
The chlorination by-products from a chlorinated culture of Microcystis aeruginosa strain TAC51 were identified and their mutagenicities were studied. A hypochlorite solution was added to the culture of TAC51 until about 0.5 mg/l of free chlorine was detected, and the mixture was stood for 60 min at the room temperature. Low molecular weight organic chlorine compounds such as chloroform, bromodichloromethane, chloral hydrate, dichloroacetonitrile, formaldehyde and isopropyl sulfonyl chloride were detected in the chlorinated culture at, ag/l levels. An AED-GC analysis detected 55 peaks, and showed 7 chlorinated substances and 7 oxidized substances which were produced by chlorination of the culture. Twenty-two compounds, including seven aliphatic hydrocarbons (e.g., hexadecane, heptadecane, methyl heptadecanes, eicosane), five fatty acids (e.g., tetradecanoic acid, hexadecanoic acid) and phytol were identified or characterized to be present in the chlorinated culture. Mutagencity assays of the chlorinated culture using Salmonella typhimurium TA100 without S9 mix showed to be mutagenic with a dose response relationship from 10.6 to 42.4 ml /plate. The mutagenicity of TA100 without S9 mix obtained by strain TAC51 is similar to the mutagenicity of tap water supplied in Japan. We found that the culture containing metabolites from M. aeruginosa strain TAC51 produced oxidized and chlorinated substances and mutagenic substances by chlorination.
