Evaluation and elimination of inhibitory effects of salts and heavy metal ions on biodegradation of Congo red by Pseudomonas sp. mutant

In this study, it was attempted to evaluate the influences and also recommended some elimination methods for inhibitory effects offered by salts and heavy metal ions. Congo red dye solution treated with mutant Pseudomonas sp. was taken as a model system for study. The salts used in this study are NaCl, CaCl2 and MgSO4·7H2O. Though the growth was inhibited at concentrations above 4 g/l, toleration was achieved by acclimatization process. In case of heavy metal ions, Cr (VI) showed low inhibition up to 500 mg/l of concentration, compared to Zn (II) and Cu (II). It was due to the presence of chromium reductase enzyme which was confirmed by SDS–PAGE. Zn (II) and Cu (II) ion inhibitions were eliminated by chelation with EDTA. The critical ion concentrations obtained as per Han–Levenspiel model for Cr (VI), Zn (II) and Cu (II) were 0.8958, 0.3028 and 0.204 g/l respectively.