The purpose of the study was to optimize the removal of Cr(VI) by means of the Trichoderma viride strain isolated from chromium mud samples a well as the Aspergillus niger and Penicillium citrinum strains from other environments. The growth of organism and removal of chromium(VI) was carried out in water solution of various chromium(VI) contents. The research was carried out at optimal pH for each fungus i.e. Aspergillus niger 4.0, Penicillium citrinum 5.0 and Trichoderma viride 4.5. During 14 days of incubation, samples of 5 ml each were collected every day in order to determine chromium(VI) content in the solution and the efficiency of bioaccumulation of this element was then specified. Furthermore, chromium contents in filtrate and mycelium were checked to verify this type of biological activity of microorganisms. The fungi culture investigated in this study could grow at 10-125 mg/l chromium concentration which indicated that it was characterized by high tolerance to various concentrations of chromium. At 125 mg/l chromium, these organisms could accumulate successfully about 90% of chromium. High tolerance of this culture can make it a potential candidate to be a heavy metal scavenger of chromium.

Three chromium resistant bacterial strains, Pseudomonas fluorescens PF28, Enterobacter amnigenus EA31 and Enterococcus gallinarum S34 isolated from tannery waste contaminated soil were used in this study. All strains could resist a high concentration of K2Cr2O7 that is up to 300 mg/L. The effect of these strains on clover plants (Trifolium campestre) in the presence of two chromium salts CrCl3 and K2Cr2O7 was studied in soil microcosm. Application of chromium salts adversely affected seed germination, root and shoot length. Bacterial inoculation improved the growth parameters under chromate stress when compared with non inoculated respective controls. There was observed more than 50% reduction of Cr(VI) in inoculated soil microcosms, as compared to the uninoculated soil under the same conditions. The results obtained in this study are significant for the bioremediation of chromate pollution.