Isolation and characterization of proteolytic microorganisms from fresh and fermented cabbage

Proteolytic bacteria from fresh and fermented cabbage were studied by cultivating in a Modified Basal Medium (MM), low in both sugar and protein content and supplemented with milk. Four proteolytic bacteria were isolated from fresh cabbage: Pseudomona pútida, Pseudomona not classified, Enterococcus hirae, and Bacillus cereus. Another strain of Ent. hirae together with B. cereus and Lactococcus lactis subsp. lactis were isolated from fermented cabbage. Substrate specificity of the isolated proteolytic bacteria was assayed by adding seven proteins, each one to MM. These bacteria were able to hydrolyze from low molecular weight proteins (hemoglobin, bovine serum albumin) to high-molecular weight proteins (gelatin, gluten). This study allowed isolating, among others, a glutenolytic L. lactis subsp. lactis strain, a possible non pathogenic caseinolytic Ent. hirae strain, and a Ps. not classified strain which hydrolyzed six of the seven proposed substrate proteins. Through the utilization of a simple and certain method extracellular protease-producing bacteria, potentially useful in different industries, were isolated from an economic and easily available source: fresh and fermented cabbage.