Maximizing production of Penicillium cyclopium partial acylglycerol lipase.

Penicillium cyclopium partial acylglycerol lipase production was maximized in shaken batch culture. The effect of inoculum size and substrate concentration on the lipase activity released in the culture medium was visualized using a surface response methodology based on a Doehlert experimental design. The main advantage of this approach is the low number of experiments required to construct a predictive model of the experimental domain. Substrate percentage (corn steep, w/v) ranged from 0.1% to 1.9% and inoculum from 100 spores/ml to 3,200 spores/ml. We determined that an optimal set of experimental conditions for high lipase production was 1.0% substrate and 3,200 spores/ml, with initial pH 5.0, temperature 25 degrees C and shaking speed 120 rpm. Between the conditions giving the minimum and the maximum lipase production, we observed a three-fold increase in both the predicted and the measured values.

Optimal design for the maximization of Penicillium cyclopium lipase production.

Penicillium cyclopium triacylglycerol lipase production was maximized in stationary batch culture. We used a surface response methodology based on a Doehlert experimental design to study the effect on the lipase activity released in the culture medium of the three most important factors: substrate concentration, pH and inoculum. Besides reducing the number of experiments required for optimization, this technique allowed us to quantify the lipase activity in any part of the experimental domain.We determined an optimal set of conditions for high lipase production: 1% substrate (corn steep), pH 5.5 and an inoculum of 10(4) spores/ml. Between conditions giving the minimum and the maximum lipase production, we observed a nine-fold increase of both the predicted and measured values.

Production of extracellular lipases by Penicillium cyclopium purification and characterization of a partial acylglycerol lipase.

Penicillium cyclopium, grown in stationary culture, produces a type I lipase specific for triacylglycerols while, in shaken culture, it produces a type II lipase only active on partial acylglycerols. Lipase II has been purified by ammonium sulfate precipitation and chromatographies on Sephadex G-75 and DEAE-Sephadex. The enzyme exists in several glycosylated forms of 40-43 kDa, which can be converted to a single protein of 37 kDa by enzymatic deglycosylation. Activity of lipase II is maximal at pH 7.0 and 40 degrees C. The enzyme is stable from pH 4.5 to 7.0. Activity is rapidly lost at temperatures above 50 degrees C. The enzyme specifically hydrolyzes monoacylglycerols and diacylglycerols, especially of medium chain fatty acids. The sequence of the 20 first amino acid residues is similar to the N-terminal region of P. camembertii lipase and partially similar to lipases from Humicola lanuginosa and Aspergillus oryzae, but is different from Penicillium cyclopium lipase I. However, it can be observed that residues of valine and serine at positions 2 and 5 in Penicillium cyclopium lipase II are conserved in Penicillium expansum lipase, of which 16 out of the 20 first amino acid residues are similar to Penicillium cyclopium lipase I.