Cometabolism in the Biodegradation of Benzene, Toluen, and p-Xylene Mixture by Isolated Pseudomonas fluorescence BE103

Hye-Kyung Lim, Jang-Young Lee and Hak-Sung Kim

A microorganism showing degradative activity towards benzene and toluen and p-xylene(BTX) was isolated from an activated sewage sludge and was tentatively identified as Pseudomonas fluorescence BE103. This strain was found to utilize benzene and toluen as growth substrates, but to degrade p-xylene in the obligate presence of a growth substrate. The metabolic product resulted from the cometabolismof p-xylene was identified as 3, 6-dimethylpyrocatechol by LC/MS analysis, and the metabolic pathway was analyzed to be similar to the tod pathway. From the kinetic studiesdone regarding BTX biodegradation using Pseudomonas fluorescence BE103, it was revealed that the cometabolism of p-xylene is significantly affected by the ratio of growth substrate concentration to biomass concentration, and that the cometabolism of p-xylene initiates only when this ratio was about 0.03.