engleski

Proteolytic activity of the functional starter cultures for cheese production

The proteolytic system of lactic acid bacteria (LAB) is essential for their growth in milk and contributes significantly to flavour development in fermented milk products. The aim of this research was to investigate the proteolytic activity of the functional starter cultures for cheese production. Casein hydrolysis by autochthonous LAB, previously defined as starter cultures, was monitored by agar-well diffusion test, SDS-PAGE and Anson´s method. Lactobacillus helveticus M92 exhibited the highest proteolytic activity among other tested starter cultures strains, with the fastest acidification rate and the highest pH decrease after overnight incubation in skim milk. The presence of prtH2 gene in L. helveticusM92 and Enterococcus faecium A7 was confirmed by PCR amplification with specific primers. Furthermore, SDS-PAGE LC-MS/MS analysis of insoluble proteome of L. helveticus M92 enabled identification of several proteins involved in proteolytic system of L. helveticus such as protease PrtM as well as proteins involved in Opp peptide transport system and the intracellular peptidases PepE, PepN, and PepQ.

proteolytic activity; functional starter cultures; cheese

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