Synergistic effect of partially hydrolyzed guar gum on Clostridium butyricum in a synbiotic combination for enhanced butyrate production during in-vitro fermentation

Background: Clostridium butyricum is a butyrate-producing beneficial bacterium and is generally recognized as a significant indicator of appropriate gut microbial metabolism in human health. Objective: The synergistic effects of commercially available prebiotic partially hydrolyzed guar gum (PHGG) dietary fiber as a carbon source on a butyrate-producing bacterial strain were evaluated during in-vitro fermentation with Clostridium butyricum bacterial strain in a basal medium. Additionally, their prebiotic activities were compared to those of other dietary fibers.  Methods: The examined functional dietary fiber substrates (PHGG, LMW-PHGG, indigestible dextrin, and inulin) demonstrated selective prebiotic effects on pH variation of a basal medium, leading to enhanced bacterial growth and butyrate production with Clostridium butyricum bacterial strains during in-vitro fermentation.  Results: Prebiotic PHGG supplementation had the highest fermentability among dietary fibers, resulting in greater bacterial growth (OD660: 1.93 ± 0.01) of the Clostridium butyricum strain and enhanced butyrate generation (4.52 ± 2.09 mM) after cultivation in a basal medium. A significant difference in promoting bacterial growth (p < 0.05), pH reduction (p < 0.05), and butyrate production (p < 0.05) compared to indigestible dextrin and inulin was observed. Mannose demonstrated the strongest butyrogenic effect and improved fermentability on the Clostridium butyricum, among the studied prebiotic monosaccharides (galactose, glucose, and starch). The order of bacterial growth and butyrate synthesis was mannose > galactose > glucose > starch. The PHGG with a relatively lower molecular weight (LMW-PHGG) exhibited the improved bacterial growth of Clostridium butyricum and demonstrated the highest butyrate production after cultivation in a basal medium. A similar trend was observed when Clostridium butyricum was cultivated in-vitro using PHGG-supplemented artificial intestinal fluid containing MRS-agar medium.  Conclusion: These findings suggest that the symbiotic combination of prebiotic PHGG and probiotic Clostridium butyricum could have major industrial applications as a therapeutic adjuvant for improved gastrointestinal health. Keywords: Partially hydrolyzed guar gum, synbiotic, prebiotic, probiotic, Clostridium butyricum, butyrate production