Ability of thermophilic lactobacilli to hydrolyze milk and vedgetable proteins

MICAELA PESCUMA; MARÍA BEATRÍZ ESPECHE TURBAY; FERNANDA MOZZI; GRACIELA FONT DE VALDEZ; GRACIELA SAVOY; ELVIRA MARÍA HÉBERT

Estambul

Congreso; Food Microbiology Congress 2012; 2012

The cell envelope-associated proteinase (CEP) oflactobacilli has a key role for bacterial nutrition and contributes to thedevelopment of the organoleptic properties of fermented milk and vegetable products;moreover, it can release bioactive health-beneficial peptides from milkproteins and diminish allergic reactions. The aim of this study was to comparethe ability of industrially relevant species of thermophilic lactobacillistrains to hydrolyze proteins from animal (caseins and β-lactoglobulin)and vegetable (soybean and wheat) sources. In addition, the influence of the peptidecontent in the growth medium on the CEP activity was evaluated. Lactobacillus delbrueckii subsp. lactis (CRL 581 and 654), L. delbrueckii subsp. bulgaricus (CRL 454 and 656), L. acidophilus (CRL636 and 1063) and L. helveticus (CRL 1062 and 1177) weregrown in a chemically defined medium supplemented or not with casitone (1%). Proteinhydrolysis was evaluated by SDS-PAGE and RP-HPLC. Proteinase production wasinhibited by the presence of casitone in different extent and was Lactobacillus species-dependent; the L. delbrueckii subsp. lactis species was the most affected (97-99%inhibition) while L. acidophilus theleast influenced one (33-50% inhibition). All strains hydrolyzed mainly β-caseinwhile the degradation of α-casein was strain-dependent. Contrariwise, k-Caseinwas poorly degraded by the studied strains. L.delbrueckii subsp. bulgaricus CRL656, L. acidophilus CRL 636 and L. helveticus CRL 1062 were able to hydrolyzethe major milk allergenic protein β-lactoglobulinwhile L. delbrueckii subsp. lactisstrains, L. delbrueckii subsp. bulgaricus CRL 656 and L. helveticus CRL 1177 degraded the gliadincereal protein in a higher extent. Respect to soy proteins, the L. acidophilus and L. helveticus strains showed the lowest proteolytic ability. Thisstudy deepens into the understanding of the proteolytic diversity of lacticacid bacteria for exploiting this complex system in the manufacture of novelfunctional foods. The rational selection of proper strains when formulatinghydrolyzed food products of different origin (dairy or vegetable) is of utmostimportance since proteinases specificities are strain-dependent.