Rhodococcus erythropolis (ATCC 4277.1) is a streptomycin resistant mutant of ATCC 4277, which can decolorize the sulfonated azo dye of Orange II and Amido Black. Pseudomonas luteola is a decolorizing strain, which was isolated from sludge resulting from the treatment of dyeing wastewater. This study had two purposes: 1) to determine the color removal capacity of R. erythropolis (ATCC 4277.1) for Red 22, V2RP and RP2B dyes; and 2) to compare the decolorization capability of R. erythropolis (ATCC 4277.1) to that of P. luteola, a wild type decolorizing strain.
R. erythropolis (ATCC 4277.1) grew well in broth containing the azo dyes of Red 22, V2RP or RP2B, and the color of azo dyes could be removed within five days of incubation. The total percentage of color removal was 70%, 30% and 23%, respectively. Color removal by R. erythropolis occurred through a process of degradation, since after five day's incubation in a dye containing broth, the color of R. erythropolis cells remained the same as their original pinkish white color. Comparison of the color removing ability between R. erythropolis and P. luteola showed that the specific color removal (SCR) of R. erythropolis was 1.52 mg of RP2B degraded per gram of dried cells, and that of SCR of P. luteola was 31.7 mg, which was 30 fold higher than that of R. erythropolis.