Lactic acid bacterial diversity in Brie cheese focusing on salt concentration and pH of isolation medium and characterisation of halophilic and alkaliphilic lactic acid bacterial isolates

Abstract

Latently existing non-starter lactic acid bacteria (NSLAB) were isolated from the French Brie de Meaux cheese using 12 isolation media with different NaCl concentrations and pH. Lactobacilli were frequently isolated using lactobacilli MRS agar, generally used for LAB isolation. Halophilic NSLAB (Tetragenococcus halophilus and Tetragenococcus koreensis) and slightly alkaliphilic NSLAB (Vagococcus lutrae), not detected using lactobacilli MRS agar or PCR-DGGE, were isolated using saline or alkaline media at log 6 to 8 cfu g−1 in the cheese rind. Their NaCl and pH optima were close to those of their isolation conditions. Phylogenetic independence of the T. halophilus isolate and genome characteristics and growth behaviour that allow T. koreensis and V. lutrae to survive in cheese rind via aerobic production of acetate from lactose were revealed. Thus, general laboratory isolation procedures should include various NaCl concentrations and pH conditions to capture a diversity of NSLAB in a living state from cheese.