Study Of Human Small Intestinal Microbiota And Gut Microbiota Of Liver Transplantation Recipients

The number of human microorganism is about100trillion,10times more than the number of somatic cells and germ cells. In this way, human microbiota, regarded as the second human genome, forms an organ which takes part into the metabolism. Human intestinal microbiota, containing the greatest amount of organisms, have a critical influence on human health, nutrition and growth. Recently, with the development of culture-independent techniques, the knowledge about human intestinal microbiota and its effects on health and disease is increasing significantly. Increasingly more evidences show that imbalance of human intestinal microbiota has a closely relationship with many diseases, such as obesity, diabetes, inflammatory bowel disease, allergic diseases and so on. However, despite the existence of thousands of kinds of organisms, we only recognize a very small part of them. Therefore, the study on the characters of human intestinal microbiota, especially on some unstudied intestinal samples or some specific objects, would facilitate us to further understand the role of human intestinal microbiota in health and disease.In the first part, we studied the intestinal microbiota from10organ donors. Under the sterile condition, the contains from the upper jejunum, jejunoileum junction, and the terminal ileum were colected. Then, DNA was purified. With454pyrosequencing technology, we analyzed the characters of small intestinal microbiota, and compared the composition and diversity of microbiota among different locations. We attained69506high qualified16s rRNA V5-V6sequences. According to97%level of identity, all these sequences were classified into518operational taxonomic units (OTUs). There were6bacterial phylums, whose abundance were above1%, including Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes, TM7, Cyanobacteria, Fusobacteria, Bacteroidetes and one unclassified bacteria. The phylums mentioned above nearly covered85%organisms in human small intestinal. Besides, several phylums with extremely low abundance were also tested out. According to our study have shown that the conditions of human intestinal microbiota is anatomical location dependent. Human intestinal microbiota in either upper jejunum or jejunoileum junction shows no statistical significance. But the diversity of human intestinal microbiota in upper jejunum and jejunoileum junction is significantly different from that in terminal ileum.In the second part, we collected47stool specimens from liver transplant recipients in order to study human intestinal microbiota. These specimens were divided into3groups, including healthy control group (n=15), pre-liver trasnplantaton group (pre-LT)(n=17), and post-liver transplantation group (post-LT)(n=15). Then, DNA was purified. With454pyrosequencing technology, we attained527735high qualified16s rRNA sequences and1911OTUs. The results showed that all the specimens from3groups were belonged to12phylums, including Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes, TM7, Cyanobacteria, Fusobacteria, Verrucomicrobia, Tenericutes, and Synergistetes. And approximate92%of the bacteria from these specimens are from Firmicutes, Bacteroidetes, and Proteobacteria. Compared with the control group, the abundance of Proteobacteria, especially Enterobacteriaceae, in stool specimens from pre-LT group was increased. The abundance of Bacteroidetes was also increased, except for the abundance of Prevotella, which was significantly decreased. Compared with pre-LT group, the abundance of Proteobacteria in stool specimens from post-LT group was declined, while the abundance of Firmicutes was elevated. The differences between control, pre-LT, and post-LT group all reached statistically significance, and the differences between pre-LT, and post-LT group were more significant.Our study aims to explore the intestinal microbiota in liver transplantation recipients. We first adopt the techniques of Barcoded454sequence to characterize the composition and abundance of human intestinal microbiota, analyze the microbiota from different human intestinal locations, and provide the important parameters for the. further study on association among human intestinal microbiota, host metabolism, immuno-regulation, and relative diseases. Additionally, our study also discuss the changes of intestinal microbiota between pre-LT and post-LT groups, and preliminary disclose the influence of operation and immunosuppressants on intestinal microbiota, providing the critical evidences for the further study.