Fermentation conditions increasing protease production by Serratia marcescens in fresh whey

extracellular protease production in fresh whey fermented by serratia marcescens was increased by studying the influence of the most important physico-chemical operating variables. fermentations were carried out in erlenmeyer flask and in an automatic controlled bioreactor (bioflo iii), obtaining in the latter case the highest protease levels (8,800 eu/ml ± 484 ds) when working under optimized conditions. two kinds of proteases were determined in the supernatant, a major metalloprotease (84% ± 2 ds) and a minor serine protease (13%+/-2 ds). in all cases cell growth and protein degradation were modelled, and the effect of oxygen concentration on cell growth was determinate by bioflo iii and was also modelled.