Fermentation of individual proteins for protease production by Serratia marcescens

Abstract

The major whey proteins β-lactoglobulin, α-lactalbumin, bovine serum albumin (BSA) and immunoglobulins were tested as the sole source of carbon and nitrogen for producing proteases by fermentation with Serratia marcescens. Cell growth, protein consumption and protease production were monitored during these fermentations. The maximum level of protease activity was achieved with BSA. Several substances described as important factors in protease synthesis were then added as supplements to a medium prepared with BSA to ascertain their influence on protease production. Likewise, in order to study the possibility of a synergic effect of whey proteins on protease production, a protein mixture simulating the protein composition of whey was also tested. However, low levels of activity were obtained, similar to those achieved with β-lactoglobulin. These results were also compared with those obtained when real whey is employed as substrate. A complete turnaround in the tendency of the kind of protease produced was found when the culture medium was solely based on bovine proteins and salts.