Communautés microbiennes de légumes fermentés domestiques

International audienceAbstractIntroduction and objectiveFermentation is an ancestral process of preserving food, which has recently received a renewed interest because of its natural image, nutritional interest, and potential for innovation. Excepted sauerkraut, fermented foods issued from vegetables have been little consumed in Western Europe, in contrast with central Europe and Asia. FLEGME, for “Fermentation des LEGuMEs” (i.e. vegetables in French), is a citizen science project thatgathers various actors: citizens, SMEs, agricultural schools, culinary journalists, researchers, among others. One of its goal is to characterize the microbial communities and the safety of home-made fermented vegetables.Material and methodsHome-made fermented vegetables were collected from citizens that manufacture this type of products for their personal consumption. Several microbial groups were targeted: lactic acid bacteria (LAB), total aerobic bacteria, Enterococcus, Enterobacteriaceae, spore-formingbacteria, as well as some pathogenic bacteria. pH was also measured.Results and discussionA set of 75 home-made samples were received. They included 23 types of legumes, the most represented being cabbage (27%, 7 varieties), followed by carrots (19%) and beets (12%). Their median pH was 3.6, with 87% of samples between 3.2 and 4.0. Only 2 samples had a pH over 4.5. LAB represented the dominant population. Their concentration varied from non-detectable values to 6x108 CFU/g, with a median concentration of 7.5x104 CFU/g. No significant relation was found between LAB counts and the type of vegetable. However, a significant effect of the age of samples (from 2-week-old to 4-year-old) was observed: high LAB counts were most frequent observed in young samples (< 100 days). Yeasts were detectedin nearly half the samples, with counts ranging from 102 to 9x107 CFU/g. Enterococci were detected in only 5 samples at counts < 105 CFU/g, spore-forming bacteria in 41 samples at counts ranging from 10 to 104 CFU/g. No pathogenic bacteria (Escherichia coli, Clostridium perfringens, coagulase positive staphylococci, Salmonella, Listeria monocytogenes) were detected. This first view of the microbial community of fermented vegetables based on culture-dependent analysis will be completed by 16S rRNA gene metabarcoding