Characterization and selection of Lactobacillus sakei strains isolated from traditional dry sausage for their potential use as starter cultures

Abstract

A total of 36 Lactobacillus sakei strains isolated from traditional dry sausage, produced without the use of starter cultures, were characterized in respect to their technological properties, i.e. growth and acidification kinetics, ability to grow at different temperatures, pH values or salt concentrations, gas production from glucose, heme-dependent catalase activity, inhibitory activity against pathogens and proteolytic and lipolytic activities. Growth rates were comprised between 0.12 and 0.55 gen/h; while acidification rates varied from 0.01 and 0.07 pH unit/h. All isolates were able to grow at pH 4.2–9.6 and at 15 °C on acetate agar supplemented with 4% NaCl, but were not able to grow at 0 and 45 °C and with 10% NaCl in the same pH conditions. However, 97% of the isolates were able to grow at 4 °C, but only 11%, and 55% were able to grow at pH 3.9 and with 6.5% NaCl, respectively. All isolates were homofermentative from glucose. Heme-dependant catalase activity was found for 97% of the isolates and 3% displayed antibacterial activity against Listeria innocua. Most isolates showed leucine and valine arylamidase and only one exhibited a lipase (C14) activity. Two strains were selected using a multi-variate analysis. Both of them showed a panel of properties highly desirable in sausage fermentation. We propose the use of these strains, in combination with coagulase-negative staphylococci as starter cultures in the studied small-scale facility in order to improve and standardize sausage safety and quality while preserving their typicality.