Biodiversity and technological-functional potential of lactic acid bacteria isolated from pseudocereals and hemp seeds

Pseudocereals as Quinoa (Chenopodium quinoa), Chia (Salvia hispanica), Amaranth (Amaranthus caudatus), Buckwheat (Polygonum fagopyrum) and Hemp (Canapa sativa) produce seeds with high protein and essential amino-acid content. Moreover they are considered a good source of fiber, minerals, polyphenolic compounds, omega-3 and omega-6 fatty acids. In addition, the lack of gluten makes these seeds suitable for new consumers and celiac subjects. The use of these flours is limited due to the low baking and sensory quality of the final products, however strategies such as fermentation could improve both characteristics. The aim of this study was to identify and characterize lactic acid bacteria (LAB) communities present in these seeds in view to design novel functional starter cultures for these flours. Identification and intra-species differentiation allowed to group 66 isolates within five LAB species: Pediococcus pentosaceus (dominant in Buckwheat, Chia and Hemp) Lactobacillus paracasei (prevalent in Amaranth), Leuconostoc mesenteroides and Enterococcus mundtii (common in Quinoa) and Enterococcus faecium. The characterization of 19 representative LAB strains was focused on the technological properties (acidification, proteolytic and amylolytic activities) and the safety characteristics (biogenic amines production, antimicrobial activity against Listeria innocua and Listeria monocytogenes and antibiotic susceptibility) by both traditional and molecular approaches. All strains were able to acidify the medium to pH 4.2 - 4.5 after 24 h except for enterococci. No strain showed amylolytic and amino-acid decarboxylase activities, whereas some proteolytic activity was found in all lactobacilli strains. Three strains of L. paracasei were susceptible to all assayed antibiotics, while most of the strains displayed a double resistance pattern (Kanamycin and Tetracycline). Interestingly, two strains of pediococci exhibited antagonistic activity against Listeria. All these data allowed the selection of one Lactobacillus paracasei and two Pediococcus pentosaceus strains as good candidates to be evaluated as starter cultures for the production of gluten-free fermented foods.