[Diversity analysis of luminal and mucosa-associated microbial communities in obese mice]

Objective: Gut microbiota have been reported to be able to regulate host metabolism and is closely associated to obesity. The purpose of this study was to explore the differences between the diversity of luminal and mucosa-associated microbial communities in obese mice. Methods: Colonic luminal contents and colonic mucosa were separately collected from 10 obese mice fed with high-fat diet for 12 weeks. DNA of gut microbiota was extracted and micro flora populations were analyzed by Illumina sequencing. Species annotation, diversity analysis, and species difference analysis were conducted. Results: The microbial flora from colonic contents had similar richness, evenness and overall structure to those from colonic mucosa (ACE index 250 vs. 285, Chao index 257 vs. 291, Shannon index 3.84 vs. 3.97, Simpson index 0.05 vs. 0.06, all P>0.05). However, there were differences in the microbial composition on specific levels. At the phylum level, colonic contents had higher abundance of Bacteroidetes (56.08% vs. 27.25%, P=3.21×10(-5)), while colonic mucosa had higher abundance of Firmicutes (49.09% vs. 34.27%, P=0.03) and proteobacteria (18.48% vs. 3.62%, P=0.000 9). At the genus level, butyrate-producing bacteria-Lactobacillus was more abundant in colonic content (LDA score=3.89), whereas gram-negative genus Helicobacter, Sphingomonas and Desulfovibrio were relatively abundant in colonic mucosa (LDA score=4.78, 3.59 and 4.11, respectively). Conclusion: There were differences in microbial composition at the phylum and genus levels between microbial flora from colonic contents and colonic mucosa, although they had similar richness, evenness and overall structure.