To maximise growth-associated -glucuronidase production
under control of the constitutive PGK promoter, the S. cerevisiae
MH1000pbk10D-glu should be grown in exponential fed-batch culture at specific growth rates close to the crit value of 0.12 h−1
where the biomass yield is at its maximum due to minimal ethanol
production. The highest final concentration of -glucuronidase
obtained from such a culture was 14.03 mg/L.
Using constant kLa as basis for process scale-up proved to be
an effective strategy, given the close to theoretical biomass yield
attained in aerobic cultures of S. cerevisiae at both laboratory and
pilot scale. At larger scale, the specific growth rate should be
E. Anane et al. / Biochemical Engineering Journal 81 (2013) 1 –7 7
carefully controlled well below crit to avoid the short-term Crabtree effect, possibly resulting from localised pockets ofhigh glucose
concentration at the feed entry point due to less efficient mixing