Characterization and in vitro prebiotic activity analysis of succinoglycan produced by Rhizobium radiobacter

Abstract

In this study, a novel succinoglycan (COGs-3) was produced and purified from Rhizobium radiobacter ATCC 13333, and its structural characteristics, physical properties, and in vitro prebiotic activity were investigated. The COGs-3 production was 2.761 g·L−1 after single-factor and response surface optimizations. The molecular weight and molecular formula of COGs-3 were 1584 Da and C59H92O49. The structure of COGs-3 consisted of β-Glcp-(1→3)-β-Glcp-(1→3)-β-Glcp-(1→6)-β-Glcp-(1→6)-β-Glcp-(1→4)-β-Glcp-(1→4)-β-Glcp-(1→3)-α-Galp modified with two succinate and one pyruvate groups based on ultraviolet–visible, Fourier transform infrared spectroscopy, high-performance gel filtration chromatography, elemental, monosaccharide composition, matrix-assisted laser desorption/ionization time of flight tandem mass spectrometry, methylation, and nuclear magnetic resonance analyses, which was the type of succinoglycan. In addition, the thermal gravimetric and differential scanning calorimetry analyses showed that 40.23 % of COGs-3 maintained physical integrity when the temperature reached 600 ℃ and the melting point was 171.42 °C, which confirmed that COGs-3 had good thermal stability. The effects of COGs-3 on healthy human gut microbiota in vitro were also studied. COGs-3 was not digested by digestive juice and significantly increased the relative abundances of Bifidobacterium and Lactococcus and decreased the abundance of Megamonas and klebsiella. In addition, COGs-3 considerably promoted short-chain fatty acids biosynthesis. This work presents the first report on the in vitro prebiotic properties of succinoglycan, thereby providing new ideas for the application and development of succinoglycan.