Diversity of intestinal bacterial lactase gene in antibiotics-induced diarrhea mice treated with Chinese herbs compound Qi Wei Bai Zhu San.

The current investigation is trying to study the impact of the mixture of Chinese herbs Qi Wei Bai Zhu San (QWBZS) on bacterial lactase gene from antibiotics-induced diarrhea (AAD) mice, as the good curative effect of QWBZS on diarrhea. Mice (6 mice per group) were randomly selected as control, model and treatment groups. To induce diarrhea, mice in both model and treatment groups were intragastrically injected with mixture of gentamycin sulfate and cefradine (23.33 mL kg-1 day-1) twice per day and continuously for totally 5 days. After the success of establishing diarrhea model, the mice in treatment group were gavaged with QWBZS for 3 days. Intestinal contents in all three groups were then collected and DNA was extracted in aseptic environment for the following sequencing. The results showed that mice from QWBZS treatment group had obviously detectable levels of intestinal bacteria, such as Actinobacteria, Firmicutes and Proteobacteria, which produce phyla lactase specifically. In comparison with other groups, the mice in treatment group had more abundant expression of lactase gene from Acidovorax sp. KKs102, Stenotrophomonas sp. LMG11000, Pseudomonas oleovorans, Eggerthella and Burkholderia. Interestingly, the Shannon index decreased significantly after the treatment with QWBZS (P < 0.01 or P < 0.05). 63.1% of lactase genes detected in the mice in treatment group were unclassified, and 32.8% of them were non-homologous to any fragments in the gene bank, which means that most of lactase-producing bacteria are novel. Our results indicate that treatment with QWBZS did not increase the diversity of bacterial lactase gene. Its curative effect on diarrhea may be relevant to its role in facilitating the growth of novel or some key lactase-producing strains.