Impact of exogenous strains on in vitro fermentation and anti-colon cancer activities of maize resistant starch and xylo-oligosaccharides

The aim of this study was to assess the potential impact of 10 exogenous strains on acid production of maize resistant starch (RS) and xylo-oligosaccharides (XOS) during in vitro fermentation and on anti-colon cancer activities of fermentation products. Maize RS and XOS were fermented in vitro by the fecal extract from healthy adults in the absence and presence of one exogenous strain culture. Fermentation products were measured for their acetate, propionate, butyrate, and lactate contents, and growth inhibition on human colon carcinoma (HCT-116) cells. These strains in general conferred fermentation products with increased acetate, propionate, and butyrate contents, enhanced lactate conversion, and different growth inhibition on HCT-116 cells. Correlation analysis results demonstrated that butyrate and lactate contents of fermentation products made respective positive and negative contribution to the measured growth inhibition ( p < 0.05); however, acetate and propionate contents made an insignificant contribution to the measured growth inhibition ( p > 0.05). These results were mostly consistent with those from confirmation trials using standard acid solutions for the cells. It is highlighted that these strains had beneficial intervention in colonic fermentation of maize RS and XOS and anti-cancer activities of fermentation products, rendering lower lactate and higher butyrate contents and especially higher anti-colon cancer activities.