Purpose: In this study we wanted to monitor fecal microbial profiles of 21-day-old male C57BL/6 mice (n=24) exposed to 15 days of dietary supplementation.
Methods: A probiotic diet (VSL#3) and a prebiotic diet (potato starch) were compared to a standard diet (n=8 for each group). Body weight, food, and water intake were monitored periodically. Fecal microbial profiles were obtained through qPCR using group-specific 16S RNA primers (total bacteria, enterobacteria, bifidobacteria, lactobacillus).
Results: The potato starch group showed higher body weight than the controls (P<0.05), but was similar to the VSL#3 group. No difference in weight was observed between the VSL#3 group and the controls. The large intestine weight of the potato starch group was higher than the controls and the potato starch group (P<0.05). The qPCR data showed that 500 pg was the optimal DNA loading amount for the standards (Escherichia coli, Bifidobacterium infantis, Lactobacillus rhamnosus), as well as fecal samples. Annealing temperatures of 55-60°C worked best for amplification. Food intake remained the same across the groups. Daily water consumption was higher in the VSL#3 group (6.65 ± 1.38 mL) as opposed to the potato starch and the control group (5.55 ± 1.21 mL, 5.54 ± 0.77 mL, respectively).
Significance: This study showed that VSL#3 and potato starch are suitable to use in a mouse model to study their impact on the gut microbiome. The probiotic water mixture using VSL#3 is a good method for incorporating beneficial bacteria in the diet without the need of invasive techniques like oral gavage.