Substrate specificity of 1,2,4-trichlorobenzene-degrader pseudomonas nitroreducens J5-1 and its chlorocatechol 1,2-dioxygenase degradation characteristics

Pseudomonas nitroreducense J5-1 can use 1,2-dichlorobenzene and 1,3-dichlorobenzene as sole carbon and energy source, whereas another 1,2,4-trichlorobenzene-degrader Pseudomonas sp. P51 cannot use 1,3-dichlorobenzene. This study focus on investigating the difference by analyzing the amino acid sequences of the two CCD genes from J5-1 and P51 despite their high similarity. This indicated that tcbC of strain J5-1 had diverged from other CCDs. CCD gene was taken as the target sequence for the detection of specific mRNA for chloroaromatic compounds degradation because it is the first gene of the MOCP. Real-time reverse transcription-PCR was used that allows the comparison of quantitative mRNA accumulation under different substrates. The expression of chlorocatechol 1,2-dioxygenase in strain J5-1 grown on 1,3-dichlorocatechol was higher than on 1,2-dichlorobenzene. The data analysis showed a general trend where 1,3-dichlorocatechol might be a better inducer than 1,2-dichlorocatechol.