Bioconversion of corn distiller's dried grains with solubles (CDDGS) toextracellular proteases and peptones

This study is aimed at developing a two-step process (fermentation plusenzymatic hydrolysis) for protease and peptone production, using a bioethanolindustry by-product - corn distiller's dried grains with solubles (CDDGS) -as the sole carbon/nitrogen and protein source, respectively. Bacilluslicheniformis was used for protease production. CDDGS concentration is themain parameter controlling protease generation, only low substrateconcentration (below 2%, w/v) induces sporulation followed by enzymeexcretion. The enzymatic peptone production process was implemented using theB. licheniformis fermentation broth (proteases) generated in the firststep as hydrolytic tool, and CDDGS as a protein source. The protein presentin CDDGS is solubilized yielding a peptone (protein concentration >80%),mainly composed of peptides and oligopeptides, soluble at practically all pHvalues. Both products, proteases and peptones, could be of great potential inindustrial processes and in nutrition and food science.