Abstract: To study the impact of a high-fat diet supplemented with different doses of banana resistant starch (RS) on the diversity of gut Actinobacteria in obese C57BL/6J mice, 40 mice were randomly divided into five groups, which were fed a conventional diet (CONV), a high-fat diet (HF) alone, supplemented with 5% (5% RS + HF), 10% (10% RS + HF), and 15% (15% RS + HF) of RS, respectively. After 8 weeks of dietary intervention, denaturing gradient gel electrophoresis (DGGE) was used to monitor the changes in the composition of gut Actinobacteria in mice. The amounts of fecal Bifidobacterium were compared among the five groups of animals by real-time fluorescence quantitative polymerase chain reaction (PCR). Cluster analysis of the DGGE profiles showed that the HF group was significantly different from the other 4 groups. All the RS groups tended to form a cluster without obvious boundaries. In addition, the diversity and abundance of Actinobacteria in the 5% RS + HF and 15% RS + HF groups were significantly lower than in the CONV and HF groups (P < 0.05) and also lower than in the 10% RS + HF group. PCR results suggested that the high-fat diet could highly significantly reduce the number of gut Bifidobacteria (P < 0.01), which, however, was very significantly increased by supplementation of 10% and 15% RS (P < 0.001). Hence, we concluded that resistant starch can restore the diversity of gut Actinobacteria in obese mice, and significantly promote the growth of Bifidobacteria in a dose-dependent manner.

Key words: banana resistant starch, gut Actinobacteria, denaturing gradient gel electrophoresis (DGGE)