Fig. (1) Average changes in chromium concentration (mg/L) over fermentation period (216 h) for the detoxification of leather dust with B. subtilis SA-6. Nutrient broth (NB), NB + B. subtilis(NBBS), NB + Chromium (NBCR), NB + Leather dust (NBLD), NB + B. subtilis+ Chromium (NBBSCR), NB + B. subtilis+ Leather dust (NBBSLD), NB + B. subtilis+ Chromium + Leather dust (NBBSCRLD).