Production of cellulases by Penicillium brasilianum IBT 20888—Effect of substrate on hydrolytic performance

Abstract

The fungus Penicillium brasilianum IBT 20888 was cultivated on three different carbon sources to investigate the effect of the carbon source on the enzyme production. The carbon sources used were Sigmacell cellulose (SC), steam pretreated spruce (SPS) and a mixture of SC, oat spelts xylan and birchwood xylan (SCXX). Enzymatic assays and capillary electrophoresis revealed clear differences among three enzyme preparations produced—both in activity levels and in the distribution between enzymes within the same class. The hydrolysis efficiency of the resulting enzyme preparations was studied on SC and SPS. The three enzyme preparations performed equally well on SPS using an enzyme loading of 25 FPU (g cellulose) −1. The enzyme preparation produced on SCXX resulted in 15% less glucose released from SC compared to the two other enzyme preparations. A lower total cellobiohydrolase level could in part explain this difference. Adsorption studies revealed that three-fold more protein was adsorbed onto SPS compared to SC due to the presence of lignin in SPS. The binding onto lignin was demonstrated to be non-specific as most proteins in the enzyme preparations were adsorbed. It was also demonstrated by the use of CE that some degradation of the enzymes occurred during the hydrolysis.