Physiological characterization and cultivation strategies of the pentachlorophenol-degrading bacteria Sphingomonas chlorophenolica RA2 and Mycobacterium chlorophenolicum PCP-1

The physiological characteristics of growth and pentachlorophenol degradation of the bacteria Sphingomonas chlorophenolica RA2 and Mycobacterium chlorophenolicum PCP-1 were studied quantitatively in liquid culture under various conditions of pH, temperature, pO2, pCO2 and PCP concentration. Concerning their metabolic properties, RA2 and PCP-1 can be regarded as r-strategist and K-strategist, respectively. RA2 showed a higher activity concerning growth and PCP degradation than PCP-1 under optimum conditions. However, PCP-1 performed better under extreme conditions. Maximum growth rates or RA2 and PCP-1 on glucose were 0.21 h−1 and 0.024 h−1 and maximum PCP degradation rates 315 and 40 μmol (g of dry cells)−1 h−1, respectively. Optimized cultivation for RA2 on a technical scale led to the production of 40 g L−1 of cell dry mass within 55 h. The cultivation strategy including pH-controlled ammonium feeding can be used to effectively produce sufficient biomass of both strains for both research and application as inoculants in soil clean-up.