Biodegradation of O-chlorophenol by Rhodopseudomonas palustris PSB-1D and Optimization of Cometabolism Substrates

A strain of bacterium, Rhodopseudomonas palustris PSB-1D, which could degrade o-chlorophenol (2-CP), was isolated and screened from shallow sediment in downstream side of the sewage outfall of an insecticide factory. The strain PSB-1D could not utilize 2-CP as the sole carbon source and energy resource. However, it could degrade 2-CP in the presence of co metabolism substrates. Seven kinds of additional compounds, malic acid, sodium propionate, sodium acetate, sodium citrate, phenol, glucose and soluble starch were taken as co metabolism substrates respectively. The effect of different co metabolism substrates on the growth of PSB-1D and degradation efficiency of 2-CP was studied under the condition of illuminated anaerobic. The results showed that sodium propionate was the most efficient co metabolic substrate which improved the bacterial reproduction and degradation efficiency. On this basis, the optimizing experiments of the adding concentration of sodium propionate were carried out. The results showed that the cell density OD₅₆₀ was 2.521 at culture time 8d, the half-life period of 2-CP was shortened to 4.9d, and the reaction rate constants increased to 0.1588 d^-1 when the adding concentration of sodium propionate was 3 g/L. With the total cellular proteins being analyzed by SDS-PAGE, induction mechanism of the key co metabolism degradation enzyme of 2-CP was studied, which showed that the specific degrading enzyme could be induced from 2-CP itself.