The Application Of Metagenomics Sequencing Technology In The Research Of Intestinal Flora And The Detection Of Clinical Samples

There is a large number of microorganisms that settle in various parts of the human body, the number of them is much higher than the number of the body’s own cells, about more than 1x1014.These microorganisms have close relation with the human body, they play an indispensable role in metabolic activity, at the same time when some microorganisms appear in related parts of human body or its number and characteristics change,the health of body will be affected, even cause some illness.Among them,the gut is the place where the most microbes settle in. Intestinal flora maintain a symbolic relationship with the human. The anaerobic environment of intestinal provides a survival condition for intestinal flora, and they involved in the metabolic activity of the human body, such as the catabolism of complex molecules in food, the synthesis of vitamin, the biological transformation of conjugated bile acid and so on. All in all, the intestinal flora can complete many metabolic functions that the cells of ourselves cannot complete.Therefore,research of the microorganisms in the body, exploration the interaction of them and the human body, the relationship between the microorganisms and disease, combination of microbiology and clinical medicine, exploration the new way of disease prevention and control, promotion human health,it will be significant.Limited by the traditional microbiology research technology, the mainly methods depend on the train separation and identification of microorganism. However, the vast majority of microbes cannot be obtained by the above methods under the existing experimental conditions. In recent years, with the development of high-throughput sequencing technology, some culture-independent technologies are playing an increasingly important role in microbial research.Metagenomics sequencing technology does not depend on the cultivation of the microbial community in samples, it extracts the nucleic acid of sample directly, completes sequencing all nucleic acid sequence of microorganisms, which can avoid the experimental pollution from the process of cultivation. Metagenomics sequencing, including 16 S r DNA sequencing and whole genome sequencing.16 S r DNA sequencing need the amplification of bacterial 16 S r RNA gene before sequencing, the latter does not depend on amplification, directly sequencing the microbial genome.Viral metagenomics is a new branch of discipline rise on the basis of the theory of metagenomics. In recent years, the viral metagenomics has significant advantages in the find of viral pathogens(known or unkonwn) and the viral dynamic monitoring. Viral metagenomics does not rely on traditional cultivation mode, directly regard all the virus’ s genetic material as the research object, identify all viruses in the sample. In recent years, many people, animals and plant virus found largely benefited from the development of the viral metagenomics.In this paper, with the aid of the metagenomics sequencing technology, we finished the exploration of flora composition and differences in the intestinal samples, screening out the pathogen in clinical samples.To explore the changes of intestinal flora under different environment, with using animal models, we extracted the bacterial nucleic acid in mice fecal from different weeks and diet condition, a total pf 16 groups, 126 samples. The V3 V4 hypervariable regions of 16 S r DNA were amplified, followed by the construction of DNA library and sequencing, then we got the abundance and composition of the flora.When we carried out the viral metagenomics sequencing in a group throat swab samples from patients with acute respiratory, the biological information analysis method was optimized and the speed of data analysis was accelerated. We found the Torque teno virus get content rise. It shows some virus infection levels of acute upper respiratory tract infection can be used as some possible biomarkers of some unknown diseases.Nucleic acid extraction is the foundation of metagenomics sequencing, it affect the later building library and the quality of the data analysis. To explore the method of sample treatment before metagenomics sequencing, We evaluated the efficiency of giant aureus genome DNA extraction by two DNA separation kit of four methods before or after the optimization with a bacteria strains as experiment object from five aspects of the genomic DNA purity and concentration, the integrity, consistency and high throughput sequencing results.Comprehensive the above content, rely on the metagenomics technology, we performed sequencing on a batch of samples of intestinal tract in mice, a batch throat swab samples of acute respiratory illness and a sample of the lung tissue from unknown etiology of pulmonary infection patients, explored the changes of the composition of intestinal flora from mice in different conditions, found that Torque teno virus get content changes in swab samples. At the same time, we carry out the method comparison and optimization aim at the DNA extraction for metagenomics sequencing. With the development of high-throughput sequencing technology, the improvement of the experiment method and the optimization the subsequent analysis scheme optimization, we believe the metagenomics will make greater contribution to the development of microbiology.