Lactic acid proteolytic system

This is due to the nature of the sourdough system where the effects of acidification and the endogenous microbial and cereal proteases all contribute to a complex set of dynamics. It is further complicated by the fact that there may be divergence between studies in terms of the particular lactoba-cilli used given that proteolytic activity is strain dependent. The enhanced proteolysis seen during sourdough fermentation has been attributed to both the proteolytic activity of lactic acid bacteria and that of cereal proteases. 

Although lactic acid bacteria (LAB) are weakly proteolytic they do possess a proteinase and a wide range of peptidases which are principally responsible for the formation of small peptides and amino acids in cheese. The genus most widely used as a cheese starter is Lactococcus, the proteolytic system of which has been studied thoroughly at the molecular, biochemical, and genetic levels. The proteolytic system of Lactobacillus spp. is less well characterized than that of Lactococcus, but the systems of both genera appear to be generally similar. 

Kok, J. (1990). Genetics of the proteolytic system of lactic acid bacteria. FEMS Microbiol. Rev. 87, 15-41. 

Savijoki, K., Ingmer, H., and Varmanen, P. (2006) Proteolytic systems of lactic acid bacteria. Appl. Microbiol. Biotechnol, 71, 394-406. 

Kunji, E. R., Mierau, L, Hagting, A., Pooknan, B., Konings, W. N. (1996). The proteolytic systems of lactic acid bacteria. Antonie Van Leeuwenhoek, 70, 187-221. 

Kok J, DeVos JM (1994) The proteolytic system of lactic acid bacteria. In Gasson MJ, DeVos WM (eds) Genetics and biotechnology of lactic add bacteria. Blackie Academic/Professional Publishers, London, New York, pp 169-210... 

Poolman B, Kunji E, Hagting A, Juillard V, Konings W (1995) The proteolytic pathway of Lactococcus lactis. J Appl Bacteriol 79 65S-75S Pritchard GG, Coolbear T (1993) The physiology and biochemistry of the proteolytic system in lactic acid bacteria. FEMS Microbiol Rev 12 179-206 Rafter JJ (1995) The role oflactic acid bacteria in colon cancer prevention. Scand J Gastroenterol 30 497-502... 

Figure 1.3. Diagram of the proteolytic systems of lactic acid bacteria, (a) Extracellular components PrtP, cell-envelope proteinase PrtM, proteinase maduration protein Opp, oligopetide permease DtpT, the ion linked trasnsporter for di-and tripeptides and Opt, the ABC transporter for peptides, (b) Intracelullar components pool of about 20-25 peptidases, including general (PepN, PepC) and specific (PepX, PepQ) peptidases, and amino acid catabolic enzymes (carboxylases, aminotransferases, etc.).

Liu, M., Bayjanov, J.R., Renckens, B., et al. (2010) The proteolytic system of lactic acid bacteria revisited a genomic comparison. BMC Genomics 11, 36. 

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