Genetic diversity and antimicrobial activity of lactic acid bacteria in the preparation of traditional fermented potato product 'tunta'.

Abstract

Fermentation microorganisms, lactic acid bacteria (LAB) and yeast from 12 samples of tunta production chain were quantified, from the native potatoes used by the process fermentation of potatoes in the river up to the final product. During fermentation, the LAB population steadily increased from 3 to 4 to 8 log CFU/g during the first 8days in the river and the yeast population increased from 2 to 3 to 3-4 log CFU/g. Overall, 115 LAB strains were isolated using a culture-dependent method. Molecular techniques and 16S rRNA gene sequencing enabled the identification of native species. In LAB isolates, members of the Lactobacillaceae (64%), Leuconostocaceae (9%) and Enterococcaceae (2%) families were identified. The most prevalent LAB species in the tunta production chain was Lactobacillus curvatus, followed by Leuconostoc mesenteroides and Lactobacillus sakei, Lactobacillus brevis and Enterococcus mundtii were also present. Only 13 LAB strains showed anti-listerial activity, and one of them, identified as En. mundtii DSM 4838T [MG031213], produced antimicrobial compounds that were determined to be proteins after treatment with proteolytic enzymes. Based on these results, we suggest that traditional fermented product-derived LAB strains from specific environments could be selected and used for technological application to control pathogenic bacteria and naturally protect food from post-harvest deleterious microbiota.