Toxic effect of o-chlorophenol on photosynthetic bacteria growth

A strain of Rhodopseudomonas sp. named 1D was isolated and screened from the shallow substrate sludge in downstream side of the sewage outfall of a insecticide factory, and the effect of o-chlorophenol with different mass concentration on the growth of 1D and dehydrogenase activity of the strain was studied respectively. The growth of 1D was obviously inhibited with the increase of o-chlorophenol mass concentraion in culture medium. In fact, 1D almost all stopped growing when o-chlorophenol mass concentration in culture medium reached 800 mg·L-1. The decrease of 1D dehydrogenase activity correlated to the increase of o-chlorophenol mass concentration. Our experiments prove that, dehydrogenase of 1D completely lost activity when the o-chlorophenol mass concentration was up to 570 mg·L-1. The results gained by using a standard method of aquatic bioassay for evaluating the toxicity of chemicals in our experiments also showed that the safe concentration of o-chlorophenol in culture medium to the strain 1D growth was 9.375 mg·L-1. Furthermore, the median lethal concentration (LC50) of o-chlorophenol affected to the strain 1D was 265.9 mg·L-1, which was much more high than LC50 to the mixed microorganism in natural waters.