Transesterification of triglycerides by dried biomass of Aspergillus sp.

Fungus isolate, Aspergillus sp. (RBD01), which was isolated from biocontaminated clarified butter was evaluated for its potential to transesterify used edible and non-edible oils for generation of alkyl esters, when used as biocatalyst as dry biomass. The work aimed at determining the potential of dry biomass of Aspergillus sp. (RBD01) to transesterify used cottonseed oil and non-edible oils viz., jatropha and karanj under various culture conditions. A conversion of oil (cotton seed) to ethyl ester to the extent of 84% was obtained at reaction temperature of 35°C, with 20% biomass and step-wise addition of ethanol at 1:5 molar ratio (oil to ethanol), within total reaction time of 36 h. Under similar conditions, transesterification of Jatropha and Karanj oils resulted in only 75 and 78.2% ethyl ester. Further, with reference to the effect of frying on transesterification, increase in frying time decreased the extent of transesterification from 84% to 30%.

Optimization of medium and process parameters for the production of lipase from an oil-tolerant Aspergillus sp. (RBD-01).

Extracellular lipase production by Aspergillus sp. (RBD-01) was monitored by modulating pH of the growth medium, ambient temperature for growth, source of nitrogen and percentage of carbon (virgin cottonseed oil). This strain was observed to be viable and produces lipase even up to 50% oil as a main carbon source. Maximum lipase activity of 21.8 U/ml was obtained with 50% (v/v) oil acting as the main carbon source and peptone (0.5% w/v) as nitrogen source. The optimum pH and temperature for enzymatic activity were observed to be 7.5 and 35 degrees C, respectively. The observations are of significance due to limited reports on use of 50% of oil as the main carbon source while obtaining significant lipase activity of 21.8 U/ml.