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In the present research work effect of different culture media, temperatures and pH on organic acid
(oxalic acid) production by Sclerotium rolfsii was studied. Qualitative estimation of organic acid was
assayed by Foster and Davis method with some modification.
To find out the best suitable medium for production of organic acid, total ten media, viz., Asthana and
Hawker’s, Basal mucor, Brown’s, Czapek’s, Dextrose-asparagine phosphate, Elliot’s, Fernando’s,
Glucose-dox, Glucose-nitrate and Potato-dextrose, agar media were tried. Out of above ten media, only
six media i.e., Elliot’s, Fernando’s, Basal mucor, Brown’s, Dextrose-asparagine phosphate and Potatodextrose
agar media were proved to be producer of organic acid. Amongst, above said six media, the
Potato-dextrose medium was found to be the best, as maximum accumulation of organic acid was
recorded in this medium followed by Dextrose-asparagine phosphate medium. The Potato-dextrose
medium was selected for further study for organic acid production by Sclerotium rolfsii.
To study the effect of various temperatures, viz., 15, 20, 25, 30, 35, 40 and 45ºC, on the production of
organic acid, the fungus was cultured on Potato-dextrose agar medium and incubated at above said
different temperatures. When Sclerotium rolfsii was incubated at very low temperature i.e., 15ºC, a little
amount of organic acid was detected. The accumulation of organic acid was increased gradually by with
increase in temperature up to 30ºC. Above 30ºC, further increase in temperature have no effect on the
production of organic acid. Therefore, 30ºC temperature was found to be the best and optimum for the
production of organic acid.
The effect of different pH values i.e., pH 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 and 9.0 on the production of organic
acid was studied and results revealed that the isolated pathogen Sclerotium rolfsii was able to produce
organic acid at very wide range of pH i.e., pH 3.0 to pH 9.0 (i.e., extreme acedic to alkaline pH). The pH
5.0 was proved to be the best for the production of organic acid, as maximum accumulation was detected
when Sclerotium rolfsii was cultured on the medium having pH 5.0.
Keywords : Sclerotium rolfsii, Organic acid, Agar media, Temperature, pH.