Biostabilization potentiality and biophysical characterization of cadmium resistant fluorescent pseudomonads and their monitoring
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Date
2006-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Concentration of cadmium, a non- essential toxic heavy metal has increased in soil in last few year posing a serious threat to environment and human health worldwide. Biostabilization using fluorescent Pseudomonads which are known plant growth promontory rhizobacteria (PGPR) has proved to be the best alternative for remediation of cadmium contaminated soils (Arya and Tewari, 2005). Cadmium resistant fluorescent Pseudomonas strains KNP9 and Z9, collected from departmental gene pool were characterized in vitro for morphological, biochemical, PGPR and biophysical properties. Biophysical properties like electrical conductance, spectrophotometry, and micrometry were performed in the presence of four different salts of cadmium(chloride, carbonate, acetate and sulphate) to study the behavior and growth pattern of the two test strains. Same strains were tested under in situ (Pot culture) studies for biostabilization potential with Indian mustard (Brassicae compestris, a well known phytoremediator ) in presence of all four salts of cadmium and to confirm biophysical behavior of the test strains.
Both the strains were able to tolerate a fairly good amount (upto 1000 ppm) of different cadmium salts (carbonate, acetate and sulphate) except for chloride and possessed all major plant growth promontory properties like siderophore, Indole Acetic Acid, phosphorous solubilization and ACC Deaminase activity. Biophysical characteristics indicated more resistance of the test strains towards acetate, carbonate and sulphate salts and less for chloride. Same results were obtained under pot culture experiments also. Direct correlation was obtained between conductance-cell growth-micrometry. Results of in situ studies showed an improvement in plant health in terms of seedling survival, height, chlorophyll content and grain yield in presence of the test strains over control pots pointing towards use of crop for fodder purpose. Results also suggest that both the strains Z9 and KNP2 can be used as an efficient bioinoculant and as efficient biostabilizers of cadmium as revealed by Atomic Absorption Spectrophotometry (AAS). However performance of the strains varied with the type of salts i.e in presence of chloride, acetate and carbonate, strain Z9 performs better than KNP2, which in turn performs better in presence of sulphate. Similar results obtained in conductance studies hint towards use of these simple techniques for selecting strains for biostabilization (bioremediation) of cadmium affected sites depending upon the type of contaminants. Immunological techniques like slide agglutination, used in present study is economical, reliable and faster and can be used in monitoring the fate of introduced population in soil
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