Antimicrobial and functional properties of lactic acid bacteria isolated from sourdoughs

The technological and functional properties of 15 LAB species previously isolated from sourdough were determined in terms of antifungal and antibacterial activities, production of GABA as a functional component and phytase activity. All sourdough isolates were capable of producing GABA and Weissella paramesenteroides N-7 and Lactobacillus paralimentarius E-106 showed the highest and the lowest production levels as 18,43 mM and 3,39 mM, respectively determined by HPLC analysis. The antifungal activity of these strains were tested against Aspergillus niger and Penicillium chrysogenum and two strains Lactobacillus paraplantarum N-15 and L. paralimentarius E-106 showed significant inhibitory effects to these mould species. Generally, different levels of antibacterial activity of these species were observed against food-borne pathogens but only one strain showed low levels of inhibitory effect to Salmonella typhimurium but not the other strains. The PCR detection of several bacteriocin coding genes revealed that all strains were harboured at least one bacteriocin gene among the tested genes. Finally, all strains showed phytase activity but these activity was dependant on strain specific conditions. This study revealed some important techno-functional properties of sourdough LAB strains which can play crucial roles on sourdough technology.