Traditionally fermented beverages fishtail palm toddy and banana pseudo- stem sap as reservoirs of Leuconostoc mesenteroides with probiotic potential

Abstract

Traditional fermented foods are integral to India’s culinary heritage and represent long-standing
empirical knowledge of naturally occurring microorganisms. Fishtail palm toddy (Caryota urens L.)
and banana pseudo-stem sap are plant-based fermented foods traditionally consumed in rural
Karnataka, yet their native lactic acid bacteria remain poorly characterized. This study investigated
these foods as potential reservoirs of probiotic microorganisms. Six bacterial isolates obtained from
fishtail palm toddy and banana pseudo-stem sap were identified as Leuconostoc mesenteroides using
16S rRNA gene sequencing and phylogenetic analysis. All isolates were Gram-positive, catalase-
negative, heterofermentative, and bile-salt tolerant. They exhibited desirable probiotic properties,
including carbohydrate fermentation, acid tolerance, favourable antibiotic susceptibility, non-
haemolytic activity, broad-spectrum antibacterial activity, survival under simulated gastrointestinal
conditions, cell-surface hydrophobicity, auto-aggregation, and co-aggregation with enteric pathogens.
Isolates from fishtail palm toddy showed comparatively greater tolerance to acidic pH, high salt
concentrations, and elevated temperatures. Among the strains, FBN7 and BPS4 demonstrated superior
functional characteristics. These findings establish traditional fermented foods as indigenous non-dairy
sources of functionally competent L. mesenteroides and provide a microbiological basis for preserving
traditional fermentation practices and exploring these strains for future applications in probiotic and
functional food development.