Diversity of lactic acid bacteria on organic flours and application of isolates in sourdough fermentation

Organic farming preserves biodiversity and organic products can be the source of many microbial species. The species diversity in organically grown wheat, spelt and rye was investigated in order to find strains suitable for sourdough fermentation. Colonies representing various morphological appearances were isolated and catalase-negative colonies were identified by mass spectrometer Microflex LT ™ MALDI-TOF. The fermentation products (lactic, acetic, formic and phenyllactic acid) were determined by high performance liquid chromatography, while the antifungal activity was determined using an overlay agar method. Wheat flours showed less microbial biodiversity than the rye and spelt flours. The most common genera in the tested flour were Lactobacillus, Pediococcus and Enterococcus. Isolated Lactobacillus farciminis, Pediococcus pentosaceus, Leuconostoc citreum and Lactobacillus brevis showed the best acidification activity. Lactobacillus brevis, Pediococcus pentosaceus, Weissella cibaria and Lactobacillus farciminis showed significant antifungal activity against A. niger 357 and Penicillium sp. 505. The prefermented medium of Lactobacillus farciminis were characterized by high content of lactic and phenyllactic acid