Abstract

USTARIZ, Francisco J; LACA, Adriana; GARCIA, Luis A  and  DIAZ, Mario. Fermentation conditions increasing protease production by Serratia marcescens in fresh whey. Rev. Téc. Ing. Univ. Zulia [online]. 2008, vol.31, n.1, pp.79-89. ISSN 0254-0770.

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.

Keywords : Fresh whey; fermentation; proteases; Serratia marcescens.