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

A feedback Re controlled fed-batch process for the recombinant production o f a soluble human N-deglycosylated recombinant beta-1,4-galactosyltransfera se (NdrGal-T) with Saccharomyces cerevisiae BT150 was investigated. Several RQ values were tested for optimal production of NdrGal-T. Four times highe r volumetric activity was reached at RQ = 1.0 (32 U l(-1)) than at all high er Re values (about 8 U l(-1)). Re, 1.0 was the best choice for both, bioma ss and enzyme production. Optimal concentration of glucose in preculture wa s 25 g l(-1). At higher values slightly more ethanol was produced than at l ower values of preculture glucose concentrations, moreover no positive effe ct 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 pre dicted scale-up possibility of feedback RQ-controlled NdrGal-T production w ith S. cerevisiae BT150 from lab to pilot-scale fermenter. (C) 2000 Elsevie r Science B.V. All rights reserved.