Faecal fermentation of partially hydrolyzed guar gum

Abstract Partially hydrolyzed guar gum (PHGG) remains undigested in the upper gastrointestinal tract, but is fermented by bacteria in the large intestine to stimulate short-chain fatty acids, particularly butyric acid. In this study, the bacterial composition in the in vitro faecal fermentation of PHGG was analyzed by real-time PCR to identify the bacteria contributing to the stimulation of butyric acid production. The production of short-chain fatty acids in a PHGG culture was compared with that in inulin and blank (no substrate) cultures. After the fermentation of the substrates by fresh human faeces, PHGG clearly promoted the production of butyric acid. The butyryl-CoA CoA-transferase gene copy number and the 16S rRNA gene copy number of the Roseburia / Eubacterium rectale group in the PHGG culture were significantly higher than those in the blank culture. These results indicated that Roseburia / E. rectale group bacteria would play an important role in the butyric acid production in vitro fermentation of PHGG.