In Vitro Prebiotic Effects of Malto-Oligosaccharides Containing Water-Soluble Dietary Fiber

Abstract

This study measured the proliferative activity of malto-oligosaccharide (MOS) as a prebiotic against Bifidobacteria, resistance to digestion in vitro, and changes during in vitro fermentation by human fecal microorganisms. It consisted of 21.74%, 18.84%, and 11.76% of maltotriose, maltotetraose, and maltopentaose produced by amylase (HATT), respectively. When 1% of MOS was added to a modified PYF medium as the carbon source, proliferation of Bifidobacterium breve was increased significantly. During the in vitro digestion test, MOS was partially degraded by intestinal enzymes. Fermentation characteristics by human fecal microorganisms were evaluated by adding 1% galacto-oligosaccharide (GOS), as well as 1% and 2% MOS as carbon sources to the basal medium, respectively. In comparison with the addition of 1% of MOS and GOS, the total short chain fatty acid (SCFA) content increased over time when 2% of MOS was added. The species diversity and richness of intestinal microbiota increased significantly with 2% MOS compared to those with 1% GOS. In addition, the 2% addition of MOS reduced intestinal pathobiont microorganisms and increased commensal microorganisms including Bifidobacterium genus. Collectively, MOS produced by amylase increased the SCFA production and enhanced the growth of beneficial bacteria during in vitro fermentation by human fecal microbiota.

Keywords: SCFA; in vitro fermentation; malto-oligosaccharide; prebiotics.

Figure 1

Proliferation effect of fructo-oligosaccharide (FOS), galacto-oligosaccharide (GOS), and malto-oligosaccharide (MOS) on Bifidobacterium breve ATCC 15,700 (A), Bifidobacterium longum ATCC 15,707 (B), and Bifidobacterium bifidum ATCC 3357 (C). The strains were cultured by adding 1% of GOS, FOS, or MOS to the modified peptone yeast extract fructose (PYF) medium without a carbon source. Data are expressed as the mean ± standard deviation, and different letters indicate significant differences at p < 0.05 between groups at the same fermentation time.

Figure 2

Changes in the sugar composition of malto-oligosaccharide (MOS) by in vitro digestion. In vitro digestion was conducted using salivary amylase, pepsin, and pancreatic enzymes. Data are expressed as the mean ± standard deviation. DP1: Glucose, DP2: Maltose, DP3: Maltotriose, DP4: Maltoteterose, DP5: Maltopentaose, Control: MOS without enzyme treatments.

Figure 3

Changes in the sugar content of malto-oligosaccharide (MOS) by in vitro fermentation. In vitro fermentation was carried out at 37 °C by inoculating feces under anaerobic conditions. Anaerobic fermentation was performed by adding 1% MOS (A,C) and 2% MOS (B,D) to the basal medium. MOS includes maltotriose (DP3), maltotetrose (DP4), and maltopentaose (DP5). Data are expressed as the mean ± standard deviation, and different letters indicate significant differences in the content of the components before and during fermentation at p < 0.05.

Figure 4

Changes in acetic acid (A), propionic acid (B), butyric acid (C), valeric acid (D), and total short chain fatty acid (SCFA, (E)) content during in vitro fermentation after the glucose and malto-oligosaccharide (MOS) addition. In vitro fermentation was carried out at 37 °C by inoculating feces under anaerobic conditions. Anaerobic fermentation was performed by adding 1% galacto-oligosaccharide (GOS), 1% MOS, and 2% MOS to the basal medium. Data are expressed as the mean ± standard deviation, and different letters indicate significant differences at p < 0.05 between groups at the same fermentation time.

Figure 5

Alpha diversity of the three groups, 1% GOS, 1% MOS, and 2% MOS. The species richness (A) and species diversity (B) were evaluated by CHAO and Shannon indexes. The 1% GOS: Group fermented with fecal microbes by adding 1% galacto-oligosaccharide (GOS) to the basal medium; 1% MOS: Group fermented with fecal microbes by adding 1% malto-oligosaccharide (MOS) to the basal medium; 2% MOS: Group fermented with fecal microbes by adding 2% MOS to the basal medium. Data are expressed as the mean ± standard deviation, and different symbols indicate significant differences at * p < 0.05 and ** p < 0.01 vs. the GOS group.

Figure 6

Relative abundance of lactic acid bacteria (A), Bifidobacterium (B), Lactobacillus (C), and Weissella (D) at the genus level. The 1% GOS: Group fermented with fecal microbes by adding 1% galacto-oligosaccharide (GOS) to the basal medium; 1% MOS: Group fermented with fecal microbes by adding 1% malto-oligosaccharide (MOS) to the basal medium; 2% MOS: Group fermented with fecal microbes by adding 2% MOS to the basal medium. Data are expressed as the mean ± standard deviation, and different symbols indicate significant differences at * p < 0.05 and ** p < 0.01 vs. the GOS group and ^# p < 0.05 vs. the MOS-1 group.

Figure 7

Relative abundance of Enterobacteriaceae (A), Enterococcaceae (B), total pathobiont strains (C), Bifidobacteriaceae (D), Lachnospiraceae (E), Ruminococcaceae (F), Bacteroidales (G), and total commensal strains (H) in the intestine at order and family levels. The total pathobiont strains are the sum of Enterobacteriaceae and Enterococcaceae, and the total commensal strains are the sum of Bifidobacteriaceae, Lachnospiraceae, Ruminococcaceae, and Bacteroidales. The 1% GOS: Group fermented with fecal microbes by adding 1% galacto-oligosaccharide (GOS) to the basal medium; 1% MOS: Group fermented with fecal microbes by adding 1% malto-oligosaccharide (MOS) to the basal medium; 2% MOS: Group fermented with fecal microbes by adding 2% MOS to the basal medium. Data are expressed as the mean ± standard deviation, and different symbols indicate significant differences at * p < 0.05, ** p < 0.01 and *** p < 0.001 vs. the GOS group and ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. the MOS-1 group.