Fed-Batch Production of Endoglucanase with a Recombinant Industrial Strain of the Yeast Saccharomyces Cerevisiae

Abstract

The Saccharomyces cerevisiae Y306 strain was used as a host for the production of a heterologous en- doglucanase coded by celA from Paenibacillus barcinonensis. The endoglucanase (EG-CelA) was ex- pressed 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 py- ruvate 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 cellulo- lytic 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.