Prebiotic Potential of Taro (Colocasia esculenta) to Modulate Gut Bacteria Composition and Short Chain Fatty Acid Production

Abstract

Taro (Colocasia esculenta) is a high fiber tuber that holds cultural and agricultural importance in the Pacific. The high fiber content offers potential as a dietary prebiotic through the presence of resistant starch (RS). RS aids gut bacteria in the production of short-chain fatty acids (SCFA), which have health benefits to the host. As such, this study aimed to investigate the effect of taro on gut bacteria composition and SCFA production through in vitro human digestion and fecal fermentation methodology.Five taro varieties (Bun Long, Mana Ulu, Moi, Kauai Lehua, Tahitian) were processed. RS concentration of taro was determined using Megazyme Resistant Starch kit. Taro samples were subjected to in vitro human digestion, replicating oral, gastric, small intestinal, and large intestinal phases. Digested taro samples were mixed with fresh human fecal slurries and fermented at 37°C for 24 hours. During fermentation, samples were collected at specific time points for analyzation of SCFA contents using gas chromatography and bacterial composition using 16S rRNA gene targeted amplicon sequencing.Tahitian variety had the highest RS concentration of 25.1%, with no significantly difference between Tahitian, Bun Long, and Moi varieties. All taro varieties exhibited statistically similar SCFA concentrations for 3-hydroxybutyric acid, acetic acid and propionic acid. Bun-Long, Tahitian, and Moi varieties exhibited significantly higher butyric acid levels than two other taro varieties. Butyric acid production had the highest correlation coefficient with RS concentration of 0.80. The bacterial community present in all taro varieties after 24 hours of fermentation was markedly different from that of the control communities, including shifts in both the Bacteriodes and Firmicutes phyla.Different taro varieties have varying RS concentrations that affect the production of SCFA in an in vitro human digestion and fecal fermentation. The production of health-promoting butyric acid shows a strong positive correlation with the resistant starch concentration of taro. Taro distinctly causes shifts after 24 hours of fecal fermentation in Bacteriodes and Firmicutes phyla. These results provide new insights into the modulation of gut microbiota through dietary interventions.USDA-NIFA Hatch C-Maīki, University of Hawaii.