STUDIES ON HEAVY METAL TOXICITY AND BIOREMEDIATION THROUGH FUNGI
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Date
2016
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ABSTRACT
The present investigation entitled “Studies on heavy metal toxicity and bioremediation through fungi” was carried under laboratory conditions in the Department of Environmental Science of College of Forestry, Dr Y S Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh during 2015 - 2016. The study comprised of 4 fungal strains viz. Aspergillus niger, Beauveria bassiana, Metarhizium anisopliae and Trichoderma harzianum which were tested for their toxicity and bioremediation for two heavy metals viz. cadmium (Cd) and mercury (Hg). The cultures of fungi were maintained under laboratory conditions in B.O.D at 25 ◦ C. The effect of graded doses of cadmium and mercury on various fungal parameters viz. radial growth, per cent growth inhibition, mycelium dry weight, spore germination percentage and uptake by fungal mycelia was studied. The whole set of experiment was laid in three replications in CRD. At 10 ppm concentration maximum radial growth was recorded for T.harzianum i.e 0.489 mm/h for cadmium and 0.484 mm/h for mercury. The mean radial growth decreased with increase in cadmium and mercury concentrations as compared to their respective controls. The dry weight of T. harzianum was significantly higher than other fungi i.e. 310 mg and 283.33 mg for cadmium and mercury respectively at 10 ppm concentration. At 10 ppm concentration M . anisopliea and B. bassiana showed maximum percent growth inhibition of 74.86 per cent and 71.71 per cent for cadmium and mercury, respectively. Spore germination percentage for all the fungi under two different doses (1 X 105spores/ml and 1 X 106spores/ml) was recorded against both the heavy metals. In all the fungi decreasing trend was observed i.e the per cent spore germination decreased with increase in the concentration of cadmium and mercury. The spore germination percentage in the presence of cadmium and mercury was in the order T. harzianum > A. niger > B .bassiana > M. anisopliae. Maximum cadmium uptake was recorded for T.harzianum (0.37 mg/g) followed by B. bassiana (0.20 mg/g) and maximum mercury uptake was recorded for M. anisopliae (0.20 mg/g) followed by T. harzianum and A. niger (0.13 mg/g). The order of fungi with respect to cadmium (Cd) uptake was T. harzianum > B. bassiana = M. anisopliae > A. niger and with respect to uptake of mercury (Hg) was M. anisopliae > A. niger > B. bassiana = T. harzianum. From the study it can be concluded that though the entomopathogenic fungus M. anisopliae had low radial growth, high growth inhibition and low spore germination at 10ppm but it had maximum mercury uptake among all the fungi and could be used for remediation of low levels of mercury (<10ppm). Whereas, the antagonistic fungus T. harzianum had maximum radial growth, lowest growth inhibition and highest spore germination and maximum uptake of Cadmium (Cd).The present study widens the scope for studying the effect of higher concentration of heavy metals in future to confirm the bioremediation ability of these fungal species.
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fungi, biological development, niger, concentrates, grading, poultry equipment, developmental stages, drying, germinability, toxicity, heavy metal toxicity and bioremediation through fungi, laboratory conditions