A STUDY OF MULTIPLE HEAVY METAL TOLERANCE IN ROOT NODULATING BACTERIA
In this study overall 22 root nodules strains of leguminous plants were used and their maximum resistance level (MRL) was determined by using iron and lead. Those strains were Tolerant,they were used for further study of cell surface properties. Surface elements like expolysaccharide, neutral beta glucans, lipopolysaccharides as well as those components that are responsible for motility of rhizobial cells. Further the strains which shows maximum tolerances were selected for co resistance to nickel, cadmium, copper, cobalt, chromium, zinc and aluminium till MIC on the basis of MRL and cell surface propertiesand it was observed that there was a decline in the growth of Rhizobium,with respect tothe increase in the heavy metals concentrations. Maximum selected isolates showed multiple tolerances
to heavy metals with minimum inhibitory concentration (MIC) for heavy metals ranging from 25 mg/ml – 350 mg/ml. whereas maximum resistance level was observed in isolates RT4d for nickel and zinc (300 mg/ml). the present study concluded that seven selected isolates maintains cell surface components as well as having multiple tolerances to other heavy metals could lead to a successful approach for bioremediation of heavy metal contaminated regions.