肠道乳糖酶的研究进展

Influence of Debaryomyces hansenii on bacterial lactase gene diversity in intestinal mucosa of mice with antibiotic-associated diarrhea

Aim

The current study aimed to investigate the effects of Debaryomyces hansenii on the diversity of bacterial lactase gene in the intestinal mucosa of antibiotic-associated diarrhea (AAD) mice.

Methods

Eighteen mice were randomly divided into three groups (6 mice per group): healthy control group, diarrhea model group and D. hansenii treatment group. The antibiotic-associated diarrhea model was established by intragastric administration with a mixture of cephradine and gentamicin sulfate (23.33 mL·kg^-1·d^-1) twice a day for 5 days continuously. After establishing the AAD model, the mice in the D. hansenii treatment group were gavaged with D. hansenii for three days, while other groups were gavaged with distilled water. Then, the intestinal mucosa of all three groups was collected and DNA was extracted in an aseptic environment for the following analysis.

Results

The difference in the richness and homogeneity of the bacterial lactase gene among all samples were inapparent, as the difference in the Chao1, ACE, Simpson and Shannon indices among the three groups were insignificant (P>0.05). NMDS analysis also showed that the distance of the samples among the three groups was unobvious. Furthermore, the bacterial lactase gene in the mucosa mainly originated from Actinobacteria, Firmicutes and Proteobacteria. Compared with the healthy control group, the abundance of lactase genes originating from Cupriavidus, Lysobacter, Citrobacter, Enterobacter and Pseudomonas was increased in the D. hansenii treatment group, while the lactase gene from Acidovorax and Stenotrophomonas decreased (p < 0.01 or p < 0.05) in the diarrhea model group and the D. hansenii treatment group.

Conclusion

D. hansenii was capable of improving the growth of some key lactase-producing bacteria like Deinococcus, Cupriavidus and Lysobacter for treating AAD.

Signification of intestinal lactase in diagnosis and treatment of infantile diarrhea

Lactase, existing in animals and gut microbes, is a disaccharide enzyme. It is usually distributed in mammalian intestinal microvillus membrane surface and in intestinal contents. Most intestinal bacteria have the ability to produce lactase. However, the lack of lactase is common in the human population, and lactase deficiency (LD) is closely related to the occurrence of infantile diarrhea. When LD occurs or the lactase activity is inhibited, children are prone to abdominal distension, intestinal cramps, diarrhea and other symptoms. When this lasts a long time, it may cause malnutrition and growth retardation. Improving the intestinal lactase activity has been used to treat infantile diarrhea. Lactase activity and lactose detection has been used for clinical diagnosis.