Effect of RQ and pre-seed conditions on biomass and galactosyl transferase production during fed-batch culture of S. cerevisiae BT150.

A feedback RQ controlled fed-batch process for the recombinant production of a soluble human N-deglycosylated recombinant beta-1, 4-galactosyltransferase (NdrGal-T) with Saccharomyces cerevisiae BT150 was investigated. Several RQ values were tested for optimal production of NdrGal-T. Four times higher volumetric activity was reached at RQ=1.0 (32 U l(-1)) than at all higher RQ values (about 8 U l(-1)). RQ, 1.0 was the best choice for both, biomass and enzyme production. Optimal concentration of glucose in preculture was 25 g l(-1). At higher values slightly more ethanol was produced than at lower values of preculture glucose concentrations, moreover no positive effect on biomass and enzyme production was found. Lower values caused not only decrease of ethanol but also decrease of biomass formation (from 1.69 g h(-1) to 0.81 g h(-1)) and enzyme overall productivity (from 2.2 U h(-1) to 0.63 U h(-1)). Successfully performed cultivation with three precultures predicted scale-up possibility of feedback RQ-controlled NdrGal-T production with S. cerevisiae BT150 from lab to pilot-scale fermentor.

Effect of growth supplements and whey pretreatment on butyric acid production by Clostridium butyricum.

Improved production of butyrate (up to 19 g/l) from whey by Clostridium butyricum was achieved by adding either yeast extract (5 g/l) or biotin (50 µg/l). Hydrolysed lactose and proteolysed whey were less effective even with added biotin.