Isolation and characterisation of the biological traits of millet-derived lactic acid bacteria

Abstract Millets are sustainable, native foods with high nutritional content. Nowadays, beneficial bacteria derived from millets have gained increased interest among food industries and consumers due to the development of starter cultures for fermentation, which are alternatives to non-dairy substitutes. This study explored the potential beneficial activity of lactic acid bacteria (LAB) isolated from six millet cultivars. 16S rDNA sequencing and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis were used to identify LAB strains. Further, biochemical characterisations were assessed for resistance to phenol, bile salts, acid, and NaCl, along with metabolite production using high-performance liquid chromatography (HPLC). Antibacterial, antioxidant, and anti-inflammatory properties were determined by biological characterisations. Among 12 isolated strains, Lactococcus lactis (SM02), Weissella cibaria (NM01 and SM01), and Enterococcus casseliflavus (BM01) from millets showed positive probiotic characteristics. These LAB isolates produced lactic acid in a range of 9,000–12,000 mg/L by utilising glucose. All LAB isolates were able to grow under acidic pH (4–5), presence of upto 0.5% bile salt, 0.3% phenol, and 5%–8% NaCl. Additionally, the cell-free supernatant of L. lactis (SM02) decreased the pro-inflammatory cytokine IL-6 levels in murine macrophage cell line compared to W. cibaria and E. casseliflavus. This study emphasises the potential of millet-derived L. lactis for developing non-dairy formulations and functional foods, paving the way for sustainable health while maintaining ecological, social, and economic resources for future generations.