Fed-batch production of endoglucanase with a recombinant industrial strain of the yeast Saccharomyces cerevisiae

The Saccharomyces cerevisiae Y306 strain was used as a host for the production of a heterologous endoglucanase coded by celA from Paenibacillus barcinonensis. The endoglucanase (EG-CelA) was expressed in S. cerevisiae using the cell-wall protein Pir4 as fusion partner to determine the secretion of the enzyme into the culture medium.The recombinant S. cerevisiae Y306 was cultivated in aerobic fed-batch culture in order to maximize the heterologous enzyme production while avoiding the occurrence of pyruvate overflow during glucose metabolism. Aiming at this, an exponential feeding policy was adopted to achieve high cell density cultivation (HCDC) at a constant specific growth rate of 0.16 h-1.The experimental results demonstrated that EG-CelA was efficiently secreted into the culture medium along the entire course of the fed-batch process as a growth linked product being expressed under the Pir4 promoter. The final titer in 2 L broth culture resulted 2.48 g, an amount in accordance with the best productions of cellulolytic enzymes, reported by other authors.Further, a simple unstructured, non segregated mathematical model was employed to highlight that in the HCDC system developed, the microbial mass grew following the set up profile along the entire time-course of process.