Fed-batch bioreactor process with recombinant Saccharomyces cerevisiae growing on cheese whey

Saccharomyces cerevisiae strain W303 was transformed with two yeast integrative plasmids containing Kluyveromyces lactis LAC4 and LAC12 genes that codify beta-galactosidase and lactose permease respectively. The BLR030 recombinant strain was selected due to its growth and beta-galactosidase production capacity. Different culture media based on deproteinized cheese whey (DCW) were tested and the best composition (containing DCW, supplemented with yeast extract 1 %, and peptone 3 % (w/v)) was chosen for bioreactor experiments. Batch, and fed-batch cultures with linear ascending feeding for 25 (FB25), 35 (FB35), and 50 (FB50) hours, were performed. FB35 and FB50 produced the highest beta-galactosidase specific activities (around 1,800 U/g cells), and also the best productivities (180 U/L.h). Results show the potential use of fed-batch cultures of recombinant S. cerevisiae on industrial applications using supplemented whey as substrate.