Effect of carbon:nitrogen ratio (C:N) and substrate source on glucose-6-phosphate dehydrogenase (G6PDH) production by recombinant Saccharomyces cerevisiae

The use of lower cost components for the cultivation of a recombinant strain of Saccharomyces cerevisiae overexpressing G6PDH, recently obtained, was investigated. The utilization of yeast extract as nitrogen source and sugar cane blackstrap molasses or glucose as carbon sources was studied for G6PDH production, under three different C:N ratios: 7, 10, and 14. The results for cell concentration, enzymatic activity and total reducing sugar concentration, evaluated throughout the cultivations, demonstrated that the use of sugarcane blackstrap molasses and yeast extract, at a C:N ratio of 10, provided the highest G6PDH activity (Pmax = 5180 U/L), with a three-fold increase in comparison to the original culture medium.