Canadian Journal of Chemical Engineering, Vol.93, No.9, 1524-1530, 2015
Application of Yeast Hydrolysate in Extracellular Lipase Production by Geotrichum candidum in Shaken Flasks, Stirred Tank, and Airlift Reactors
Lipase production by Geotrichum candidum NRRL Y-552 was studied using an alternative nitrogen source, yeast hydrolysate (Prodex-lac((R))), and soybean oil as the carbon source and inducer of lipase production. Factorial design and response surface methodologies were applied to obtain optimized conditions for lipase production in shaken flasks, defined as: 3.5g/100mL of yeast hydrolysate and 0.7g/100mL of soybean oil with an initial pH of 7.0 at 30 degrees C and 250rpm. The resulting lipase activity after 48h was 24.3U/mL (0.506U/mL(.)h), 52% higher than with peptone under the same conditions (U=the amount of enzyme required to liberate 1 mu mol of fatty acid per minute). Lipase production with the optimized medium was conducted in a stirred tank reactor and in an airlift bioreactor, both at 30 degrees C and 300rpm; the best results obtained were 15.4U/mL after 32h of fermentation (0.481U/mL.h) and 19.24U/mL after 32h of fermentation (0.601U/mL(.)h) at 1 vvm, respectively. The results presented here from both bioreactors showed similar results to a previous study with the same microorganism under the same conditions using peptone as a nitrogen source. In addition, yeast hydrolysate is a cheaper nitrogen source than peptone and yeast extract, which permits a cost reduction above 90% under similar conditions.