RETRACTED: Physicochemical and biological characterization of the EPS produced by L. cidophilus isolated from rice bran sourdough

Abstract

Abstract Spontaneously-fermented RBS contains a variety of LAB and bacterial metabolites with potential applications as sources of functional ingredients. In this work, the EPS production capacities of the dominant LAB separated from spontaneously fermented RBS was investigated. Lactobacillus acidophilus was identified as the dominant isolate via biochemical and molecular investigations. The total carbohydrate, protein and phosphorus contents of the 2.04 × 106 Da EPS were 254.9 g/L, 0.095 g/L, and 0.36% w/w, respectively. HPLC was used for compositional assessment in terms of monosaccharide constituents, revealing that glucose, galactose and maltose were the major components of the EPS produced by L. acidophilus. The EPS was identified using FT-IR, 1H and 13C NMR spectra. FT-IR analysis demonstrated the polysaccharide nature of the EPS; the presence of alcoholic, aromatic and carboxylic acid groups was confirmed via their respective stretching vibrations. The microbial EPS extracted from L. acidophilus was identified as a linear α(1 → 6) polysaccharide. Also, the percentage inhibition of DPPH by the EPS was significant (P