Characterization of wild strains ofLactococcus lactissubsp.lactisisolated from Cabrales cheese

Abstract

SummaryTwentyLactococcus lactissubsp.lactisstrains isolated from cheese made from raw milk have been, studied and compared with well known starter strains. Many of them produced acid bacteriocins resembling those of other lactic streptococci and their patterns of antimicrobial agent susceptibility were also similar to previously studied dairy strains. On the basis of their ability to clot milk they could be divided into two groups. Some strains were rapid fermenters, with highβ-phosphogalactosidase and proteolytic activities. The other group had lowβ-phosphogalactosidase activity and coagulated milk slowly, but seemed to have proteolytic activity. All the strains had plasmid DNA in amounts and sizes similar to starter strains. Aβ-phosphogalactosidase probe was constructed with plasmid DNA from aLc. lactissubsp.lactisNCDO 712 derivative. Southern hybridization located homologous sequences in chromosomal and plasmid DNA from the wild isolates that fermented lactose efficiently, but the degree of homology was lower than that observed between starter strains.

Selection of Lactic Acid Bacteria Isolated from San Simón da Costa Cheese (PDO) in Order to Develop an Autochthonous Starter Culture

“…Both Leuconostoc and Lactococcus strains presented low proteolytic activity in general, with the former presenting the lowest activity, yielding values that did not exceed 0.2 mMGly•L . These values differed between strains but were generally slightly lower than those detected by various authors for other strains of Lactococcus isolated from traditional cheeses of different origins [37] [39] [40], although they were similar to those detected by Mayo et al (1990) [41]. The majority of the Lactobacillus strains presented a proteolytic activity of between 0.1 and 0.…”

Characterisation of the technological behaviour of mixtures of mesophilic lactic acid bacteria isolated from traditional cheeses made of raw milk without added starters

“…These strains, which had been isolated and characterised in previous reports (Mayo et al . ; Herrero et al . ; Sánchez et al .…”

“…Strain propagation and design of starter mixtures A set of LAB strains has been gathered from different batches of five traditional cheese varieties made from raw cow's milk without added starters, two of which (Cabrales and Cas ın) carry a PDO label. These strains, which had been isolated and characterised in previous reports (Mayo et al 1990;Herrero et al 1996;S anchez et al 2000;Delgado et al 2002), were chosen as the base material for the design of nine experimental starter blends (Table 1). These mixtures involved combinations of strains of the subspecies lactis and cremoris and the lactis biovar diacetylactis (mixtures S1, S2, S3, S4 and S5), plus strains of the nonstarter LAB species Leuconostoc (mixture S6) or strains of both Leuconostoc spp.…”

Nucleolytic activities in Lactococcus lactis subsp. lactis NCDO 497

“…Lactococeus lactis subsp, lactis $72, D22, and INIA 39, Lactobacillus plantarum LL2 and LL442, Leuconostoc mesenteroides subsp, dextranicum L22, Leuconostoc pararnesenteroides L16, and Leuconostoc lactis INIA 110 were wild isolates from Cabrales cheese. Some characteristics of these L. lactis isolates can be found elsewhere [5]. Some reference strains, L. lactis subsp, lactis C2 and NCDO 497.…”