Aatif Amin and Zakia Latif
The aim of the present study was to isolate yeast isolates from local environment for hydrogen sulfide production to detoxify mercury containing compounds. Preliminary twenty two yeast isolates from seventy were screened out by qualitative and quantitative assay having maximum ability to detoxify mercury. Zone of inhibition ranging from 7 - 14mm in well plate method and remediation of mercury in the culture medium ranging from 2 to 19μg/ml out of 20μg/ml HgCl2 were observed. Mercury resistant isolates were further characterized for hydrogen sulfide production by growing them on Lead acetate (LA) medium. Maximum resistance to 100 μg/ml HgCl2 yeast isolates showed minimum zone of inhibition (7- 9 mm) gave darker color on LA agar plates as compared to yeast isolates sensitive to mercury. On the basis of these results seven yeast isolates were characterized by 18S rRNA sequencing as Candida tropicalis (JF896569), Candida rugosa (JF896570-71), Pichia kudriavzvii (JF896572-73), Candida xylopsoci (JF896574) and Candida inconspica (JF896575). It is concluded from our studies that Candida xylopsoci and Pichia kudriavzvii have potential to detoxify mercury 95% and 94.5% respectively from the medium containing 20 μg/ml HgCl2 within 36 hrs. Our findings suggest that both strains may have significant biotechnological role in the treatment of contaminants containing mercury before they discharge into the environment to make it friendly for living organisms
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