CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
capítulos de libros
Título:
Proteolytic systems in lactic acid bacteria
Autor/es:
MANCA DE NADRA, M.C; STRASSER DE SAAD, A.M.; FARÍAS, M.E.
Libro:
Nitrogen Compounds Metabolism by Lactic Acid Bacteria
Editorial:
Research Signpost
Referencias:
Lugar: Kerala, India; Año: 2007;
Resumen:
The complex nutritional requirements of lactic acid bacteria (LAB) induce them to use strategies to survive in poor media. The proteoliytic activity of LAB is essential for their growth by supplying available source of amino acids as growth factors. LAB has a complex proteolytic system capable of converting proteins to free amino acids and peptides necessary for growth. This system is composed by proteinases which are involved in the initial cleavage of the protein, peptidases which hydrolyze the large peptides formed and transport systems which are involved in the uptake of small peptides and amino acids. Much of the research hitherto has focused on the proteinase of lactococci but increasingly interest is now being directed towards other industrially-important genera of lactic acid bacteria, in particular, lactobacilli. As part of the industrial processes, LAB are challenged by various stress conditions that affect their metabolic activities, including proteolysis. The stress responses related to proteolysis in LAB is based on studies on L. lactis. In the lasts years it was characterized a proteolytic system in LAB from wine. Oenococcus oeni, generally responsible to carry out malolactic fermentation in wine produces an extracellular protease that is expressed in stress conditions. This enzyme is effective on the nitrogenous macromolecular fractions of red and white wines and it was characterized at a biochemical level and purified to homogeneity. Certain Lactobacillus strains are believed to produce bioactive health-beneficial peptides from milk proteins.  The casein molecules of milk are of particular interest because they are known to harbor bioactive peptides that are latent until released by proteolysis.