Characterization of Natural Isolates of Lactobacillus Strains to be used as Starter Cultures in Dairy Fermentation.

HEBERT, E.M.; RAYA, R.R.; TAILLIEZ, P.; SAVOY DE GIORI, G.

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

Elsevier Science

Año: 2000 vol. 59 p. 19 - 27

0168-1605

The technological relevant features of five homofermentative lactobacilli strains, isolated from natural fermented hard cheeses, were studied. Isolates CRL 581 and CRL 654, from Argentinean artesanal hard cheeses, and isolates CRL 1177, CRL 1178, and CRL 1179, from Italian Grana cheeses, were identified as Lactobacillus delbrueckii subsp. lactis (L. lactis) and L. helveticus, respectively, by physiological and biochemical tests, SDS-PAGE of whole-cell proteins and sequencing of the variable (V1) region of the 16S ribosomal DNA. All strains showed high levels of b-galactosidase activity. However, proteolytic activity varied widely among isolates. Strains CRL 581, CRL 654, and CRL 1177 exhibited important features and show potential for successful use as starter cultures in dairy fermentation. They hydrolyzed a- and b-caseins and were able to coagulate reconstituted skim milk in less than 16 h at 42°C. According to the substrate specificity, these proteinases have a caseinolytic activity comparable to that of the PIII-type of lactococcal proteinases. All strains did not produce inhibitor substances (bacteriocin) and were insensitive to attack by fourteen L. helveticus- and L. lactis-specific bacteriophages.