Investigation of chromium (VI) tolerant bacteria

Pseudomonas strains were isolated from a heavy metal contaminated sludge. Some of the strains grew on chromium (VI) containing medium, and others were inhibited in their growth. Cells were able to remove chromium from the medium. This ability was independent of the rate of their growth. The concentration of chromium (VI) of the media decreased with 15-20 ppm in presence of 10(9) cells. The chromium (VI) was converted into a reduced form of chromium by bacteria. The reduced form of chromium was bound in the cell wall. The bound form of chromium could be recovered more or less with different chemicals. The best percentages of recovery were achieved with NaOH solution.