CHANGE IN TOXICITY EFFECT OF MERCURY AT STATIC CONCENTRATION TO CHLORELLA-VULGARIS WITH ADDITION OF ORGANIC-CARBON SOURCES

The effect of mercury on Chlorella vulgaris is influenced to a large e xtent by organic carbon sources like glucose, glutamate, and 2-oxoglut arate which is exhibited through changes in growth and metabolic proce sses of the alga in the presence of static dose (0.200 +/- 0.004, p = 0.05) of Hg2+. Addition of the three carbon sources to the Hg2+-amende d Chu No 10(+) medium resulted in an acceleration of pigment biomass, growth, and protein content of the green alga. Glucose at all concentr ations was found to be more effective than the other two in reducing t he mercury toxicity to C. vulgaris. However, the detoxifying effect is dependent an the type of carbon sources, their concentration and days of incubation. Glucose at 5 mg/l significantly reduced Hg2+ toxicity while glutamate and 2-oxoglutarate, at this concentration, did not sho w such capacity. Similarly the degree of significance of ameliorative effect increased with increase in incubation period which, however, va ried with the carbon source. Availability of additional energy and for mation of non-toxic or less toxic mercury are the probable causes of r eduction in toxicity effects.