Biodiversity and characterization of lactic acid bacteria of amaranth sourdough

RUIZ RODRÍGUEZ, L.; VERA PINGITORE, E.; COCCONCELLI, PIER. S.; MARTOS, G.; SAAVEDRA, L.; FONTANA, C.; HEBERT, E.; VIGNOLO, G.

Nantes

Simposio; VIth Sourdough Symposium. Understanding Natural Complexity; 2015

INRA

Gluten-free Andean grains such as amaranth (Amaranthus caudatus) has attracted attention worldwide because its high nutritional value and as celiac palliative (1,2). Recently, exploration of non-wheat ancient grains-based fermentation has been carried out (3). The identification and dynamics of lactic acid bacteria (LAB) microbiota during spontaneous fermentation of amaranth sourdoughs (AS) was investigated by multiphasic approach. The doughs were fermented with daily back-slopping at 30 °C for 10 days. LAB counts for AS ranged from 4x102 to 3.5x108 CFU/g with a pH decline from 6.2 to 3.8 throughout fermentation. Presumptive LAB recovered from refreshment steps were identified by culture-dependent and -independent approaches. RAPD analysis (primers M13b, XD9) and 16S rDNA sequencing allowed grouping isolates into 5 LAB species belonging to Enterococcus (E.), Pediococcus (P.) and Lactobacillus (L.). A great diversity was observed at the beginning of fermentation, E. casseliflavus, E. mundtii and L. rhamnosus being identified. After 24 h, P. pentosaceus and L. plantarum were recognized, the latter remaining as the predominant species until the end of fermentation. By DGGE analysis high species diversity among enterococci was evidenced initially then, L. plantarum as a competitive species was established. The technological/functional and safety characteristics of representative LAB strains indicated their ability for acidification below pH 4.0 (100%); amaranth protein degradation (100%) and exopolysaccharides production (25%) while none of the strains were able to hydrolyze starch. Resistance to antibiotics of clinical importance and aminobiogenesis were found in 50% and 27.5% of the strains, respectively. Moreover, inhibitory activity against Listeria (37.5%) and Bacillus (25%) and antifungal activity against Aspergillus orizae (62.5%) were determined. Results showed that L. plantarum CRL1898 may be selected as functional starter culture for new applications.