Optimization of Oligosaccharide Production from Leuconostoc lactis Using a Response Surface Methodology and the Immunostimulating Effects of These Oligosaccharides on Macrophage Cells

Abstract

Production of oligosaccharides from Leuconostoc lactis CCK940 was optimized using a response surface methodology with a central composite design. Culture temperature and the concentrations of sucrose and maltose were used as the main factors. The predicted optimum conditions for the production of oligosaccharides were a culture temperature of 30 °C, a sucrose concentration of 9.6% (w/v), and a maltose concentration of 7.4% (w/v). Using these optimal conditions, Leuconostoc lactis CCK940 was cultured using a fermenter to produce oligosaccharides, and the resulting oligosaccharides with a degree of polymerization greater than 4 were purified by Bio-gel P2 gel permeation column chromatography and then lyophilized. When macrophages were treated with the purified oligosaccharides at concentrations of 0.1–10 mg/mL, no cytotoxicity towards the macrophages was observed. However, nitric oxide production levels were similar to those following treatment with 1 μg/mL lipopolysaccharide. The mRNA expression levels of tumor necrosis factor-α, interleukin-1β, interleukin-6, and inducible nitric oxide synthase were all also increased in a dose-dependent manner following treatment with the oligosaccharides. These data suggest that oligosaccharides produced by Leuconostoc lactis CCK940 could be used as an immune enhancer of macrophages.

Structural Analysis of Gluco-Oligosaccharides Produced by Leuconostoc lactis and Their Prebiotic Effect

“…The oligosaccharides from Leu. lactis CCK940 were produced in optimized fermentation conditions and purified as described in a previous report [14].…”

“…The CCK-oligosaccharides produced by Leu. lactis CCK940 were analyzed using a HPAEC-PAD (DX 500 Chromatography System, Dionex, Sunnyvale, CA, USA) [14]). The Leu.…”

“…Many studies have shown that oligosaccharides as prebiotics exert positive effects on the human body. They improve intestinal function, stimulate the growth of beneficial bacteria, inhibit the growth of pathogens, increase short chain fatty acids (SCFAs), reduce total cholesterol and low-density lipoprotein (LDL) cholesterol, and enhance immune function [12,13,14,15].…”

“…In our previous reports, Leuconostoc lactis CCK940, which has high glucansucrase activity, was isolated from home-made kimchi (Korean traditional fermented vegetables) and the production of oligosaccharides from Leu. lactis CCK940 was optimized [14,16]. The purified oligosaccharides from Leu.…”

“…The purified oligosaccharides from Leu. lactis CCK940 showed immunostimulating effects on RAW264.7 macrophage cells [14].…”