Comparison of cometabolic degradation of 1,2-dichlorobenzene by Pseudomonas sp. and Staphylococcus xylosus

Cometabolism of 1,2-DCB in the presence of glucose by Pseudomonas sp. and Staphylococcus xylosus was studied for the first time. The specific growth rates at 0.1 mM 1,2-dichlorobenzene, were estimated to 0.196 and 0.145 h −1 for Pseudomonas sp. and S. xylosus, respectively, and were of the same range with the values obtained in the presence of glucose only. The percentage of 1,2-dichlorobenzene consumption is ranging between 78 and 51% for Pseudomonas sp. and between 45 and 22% for S. xylosus, respectively, depending on its initial concentration. Degradation of 1,2-dichlorobenzene was followed by its dechlorination and acidification, which started after the final addition and continued till the end of the exponential phase of growth. Furthermore, attempt was made to analyze and identify by HPLC and GC–MS analysis some intermediates or end catabolic products found in the culture medium. 3,4-Dichlorocatechol was identified in both bacterial species. In the case of Pseudomonas sp. 3,4-dichlorocatechol was depleted after 24 h, followed by the appearance of 2,3-dichloromuconic acid. Contrary to Pseudomonas sp., in S. xylosus 3,4-dichlorocatechol was still present after 24 h and 5-chlorodienelactone was identified as one of its transformation products.