Abstract
A short-term system to detect enviromental mutagens is presented by using a plasmid (pSK 1002) carring a fused gene umuC-lacZ introduced into Salmonella typhimurium TA 1535. The principle of this test is that when mutagens in sample attack the DNA in the tester strain, β-galactosidase is produced in propotion to the amount of the mutagens and then reacts with o-nitrophenyl-β-D-galactopyranoside (ONPG) to produce o-nitrophenol which can be detected at 420 nm. This method showed 12 times higher sensitivity than the previous method when AF-2 was used as test compound, and major improvements made by us are as follows; ( 1 ) in order to determine the amount of produced enzyme, the volume of culture treated with the test compound was increased from 0.25 ml to 1.0 ml, ( 2 ) the poly(oxyethylene)(23)dodecyl ether and toluene were selected as loosening reagents of the cell membrane, and ( 3 ) one ml of ONPG (4 mg⋅l-1) and 45 min of reaction time were adopted. This method was applied to mutangenicity test of river waters to which clorine and chlorine-alternative disinfectants such as, chloramine, chlorine dioxide, and ozone were added.
