Identification of Clostridium perfringens AB&J and its uptake of bromophenol blue

Several microorganisms from rat and human feces and rumen fluid of cows were screened for their ability to decolorize the synthetic dyes. Consequently, a novel dye-degrading strain AB&J was isolated. Taxonomic identification including 16S rDNA sequencing and phylogenetic analysis indicated that the isolate had 99.9% homology in its 16S rDNA base sequence with Clostridium perfringens. After 27 h incubation with the strain, brillian blue R, bromophenol blue, crystal violet, malachite green, methyl green, and methyl orange were decolorized by about 69.3%, 97.7%, 96.3%, 97.9%, 75.1%, and 97.2%, respectively. The triphenylmethane dye, bromophenol blue, was decolorized extensively by growing Clostridium perfringens AB&J cells in liquid cultures under anaerobic condition, although their growth was strongly inhibited in the initial stage of incubation. This group of dyes is toxic, depending on the concentration used. The dye was significantly decolorized at a relatively lower concentration of below 50 μg ml^-1, however, the growth of the cells was mostly suppressed at a dye concentration of 100 μg ml^-1. The decolorization activity in cell-free extracts was much higher in cytoplasm than in periplasm and cytoplasmic membrane. Therefore, the enzyme related uptake of bromophenol blue seemed to be localized in cytoplasm. The optimal pH and temperature of bromophenol blue uptake for decolorization activities were 7.0 and 40°C, respectively.