Diversity of lactic acid bacteria isolated from tropical fruits of Northern Argentina and mannitol production by selected strains

RUIZ RODRIGUEZ L.G.; HARTH H.; WECKX S.; HEBERT E.M.; DE VUYST L.; MOZZI F.

Dublin

Simposio; SfAM Summer Conference 2015; 2015

AimsLactic acid bacteria (LAB) are used as starter cultures, as probiotics, and in the production of interesting compounds. Exploration of the microbial biodiversity in virgin niches may lead to the isolation of unique strains with interesting technological and/or health-promoting properties. This study aimed to isolate and identify LAB from fresh tropical fruits and flowers from Northern Argentina and to evaluate their ability to produce mannitol. Methods and resultsGuava, passion fruit and flowers, papaya, custard apple, medlar and flowers, fig, khaki and mulberries were sampled. LAB isolation was done using MRS medium; fructophilic LAB (FLAB) using FYP and MRS-F media. Gram-positive, catalase-negative isolates (785) were classified and identified by (GTG)5-PCR fingerprinting analysis of genomic DNA, numerical cluster analysis and partial sequencing of the 16S rDNA of representative isolates. The strains belonged to the species Enterococcus hirae (4), Ent. faecium (3), Ent. mundtii (1), Ent.durans (1), Ent. gallinarum (3), Ent. casseliflavus (3), Ent. faecalis (1), Weissella cibaria (3), W. fabalis (1), W. minor (9), Lactococcus lactis (3), Lc. lactis subsp. lactis (5), Lc. lactis subsp. cremoris (1), Leuconostoc mesenteroides (3), Leuc. mesenteroides subsp. mesenteroides (9), Leuc. pseudomesenteroides (34), Leuc. citreum (2), Lactobacillus rhamnosus (2), Lb. brevis (6), Lb. plantarum (1), Fructobacillus durionis (2), F. fructosus (1), F. pseudoficulneus (1) and F. tropaeoli (6). Mannitol production was determined by HPAEC-PAD in 24-h cultures of selected strains. Twenty-eight strains of Leuconostoc and Fructobacillus produced high (5.2-9.5 g/L) mannitol concentrations.ConclusionsA wide diversity of LAB and FLAB species inhabited tropical fruits and flowers, the most abundant strains belonging to the genera Leuconostoc, Enterococcus and Fructobacillus. Many of the bacterial strains tested were excellent mannitol producers. Significance of studyKnowledge on the (F)LAB communities of fruits is essential for the selection of autochthonous strains with interesting properties to further developing fermented fruit products.