Lactic Acid Bacteria from Argentinean Fermented Foods: Isolation and Characterization for their Potential Use as Starters for Fermentation of Vegetables.

Lactic acid bacteria (LAB) improve the organoleptic, nutritional and physicochemical properties of artisanal foods. In this study, we selected 31 fermented dairy and vegetable foods marketed in Tucumán city, Argentina, as sources of LAB for the production of pickles. Sixty-four isolates presumptively identified as Lactobacillus strains were screened for relevant technological properties for production of fermented foods. Most strains showed moderate to good acidification (>0.04 pH units/h) and proteolytic capabilities (free aminoacids >1 mmol/L), produced diacetyl and/or acetoin and were resistant to 4% NaCl. Based on acid production and osmotolerance, we selected six LAB strains and identified them by 16S rDNA sequencing (97-100% identity) as: Lactobacillus rhamnosus CRL2159 and CRL2164, L. plantarum CRL2161 and CRL2162, Weissella viridescens CRL2160 and W. paramesenteroides CRL2163. Relevant properties for pickle manufacturing were further assessed. At an initial pH=4.5 and 7% NaCl, L. plantarum CRL2162 and L. rhamnosus CRL2164 performed the best with high growth and inhibitory activity against Escherichia coli and Listeria innocua. There was no obvious antagonism among the selected strains that would dismiss their use in mixed cultures. Properties of the selected LAB suggest their potential as starter cultures for obtaining standardized, fermented vegetable products of high quality. The development of these new industrial starters would increase the competitiveness of production and open the country's frontiers in the canned vegetable market.