European Journal of Biotechnology and Bioscience

Authors
A. M. Saad

Abstract
Training of Mucor rouxii NRRL 1894 and Rhizopus sp. to high concentration of heavy metal cobalt (Co+2) may increase their metal uptake capacity as a mechanism of metal resistant. Mucor rouxii and Rhizopus sp. were trained to cobalt by repeated subculturing on peptone glucose solid medium containing relatively high levels of cobalt (50ppm). This process enabled these fungi to tolerate higher levels of Co+2 than their original. The half-maximal growth inhibition of Mucor rouxii and Rhizopus sp. (original) in liquid medium occurred at 37 and 30ppm of cobalt while that of cobalt-trained fungi were 80 and 50ppm, respectively. The nongrowing biomass of Mucor rouxii andRhizopus sp. effectively adsorbed insoluble-inorganic compounds when present as a mixture, also the biomass of trained Mucor rouxii and Rhizopus sp. were more efficient in removal of cobalt from solution containing up to 98.5ppm, the removal efficiency was 76.4 and 69.9%, respectively. The biomass of either organism removed considerable amounts of Mn, Ni, Cu, Zn, Cd in addition to Co when present as a mixture. The fungal biomass efficiently removed both heavy metal ions and insoluble-inorganic compounds when present as a mixture. However, the sorption capacity of cobalt was reduced from 79.9 to 64.3 and from 64.8 to 38.8% for trained Mucor rouxii and trained Rhizopus sp., respectively.