Animal gastrointestinal tract contains a complex community of microbes, whose composition ultimately reflects the co-evolution of microorganisms with their animal host. The gut microbial community of humans and animals has received significant attention from researchers because of its association with health and disease. The application of metagenomics technology enables researchers to study not only the microbial composition but also the function of microbes in the gastrointestinal tract. In this paper, combined with our own findings, we summarized advances in studying gastrointestinal tract microorganism with metagenomics and the bioinformatics technology.
Animals ; Gastrointestinal Tract ; microbiology ; Humans ; Hyperglycemia ; etiology ; Inflammatory Bowel Diseases ; etiology ; Metagenome ; physiology ; Metagenomics ; methods ; Obesity ; etiology

Advances in sequencing technology and the development of metagenomics have opened up new ways to investigate the microorganisms inhabiting the human gut. The intestinal microbiota confer protection against pathogens, contribute to the maturation of the immune system, and regulate host metabolism. The composition of gut microbiota in early life is influenced by mode of birth, diet, and antibiotics. Decreased biodiversity and alterations in the composition of the intestinal microbiota have been observed in many diseases including obesity, neonatal necrotizing enterocolitis, inflammatory bowel disease, and recurrent Clostridium difficile infection. Therapeutic options for the diseases linked to imbalance in the microbiota include modifying the gut microbiota through diet, probiotics, and fecal transplants.
Animals ; Anti-Bacterial Agents/therapeutic use ; Clostridium difficile/isolation & purification/pathogenicity ; Enterocolitis, Pseudomembranous/drug therapy/microbiology/pathology ; Fatty Liver/etiology/microbiology ; Humans ; Inflammatory Bowel Diseases/etiology/microbiology ; Intestines/*microbiology ; *Microbiota ; Obesity/etiology/microbiology

OBJECTIVETo investigate the changes in fecal flora and its correlation with the occurrence and progression of inflammatory bowel disease (IBD).

METHODSWe collected fresh fecal specimens from 167 IBD patients (including 113 with ulcerative colitis and 54 with Crohn's disease) and 54 healthy volunteers. The fecal flora was analyzed by gradient dilution method and the data of inflammatory markers including WBC, PLT, CRP and ESR were collected to assess the association between the fecal flora and the inflammatory markers.

RESULTSThe species Enterrococcus (6.60∓0.23, P<0.01), Saccharomyces (2.22∓0.27, P<0.05), Bacteriodes (5.57∓0.28, P<0.001), Bifidobacterium (5.08∓0.30, P<0.01), Peptococcus (6.22∓0.25, P<0.001), Lactobacillus (6.00∓0.26, P<0.001), and Clostridium (3.57∓0.30, P<0.05) all increased significantly, while Eubacterium (1.56∓0.24, P<0.01) reduced markedly in patients with ulcerative colitis compared with those in the control subjects. Enterrococcus (6.93∓0.28, P<0.01), Saccharomyces (2.73∓0.37, P<0.01), Bacteriodes (4.32∓0.52, P<0.05), Bifidobacterium (4.88∓0.42, P<0.05), Peptococcus (6.19∓0.32, P<0.01) and Lactobacillus (4.73∓0.47, P<0.001) all increased significantly and Eubacterium (1.01∓0.29, P<0.01) and Clostridium (0.87∓0.31, P<0.01) decreased in patients with Crohn's disease. The positivity rates of bacterial culture were consistent with the results of quantitative analysis of the fecal flora. The changes in fecal flora did not show a significant correlation with these inflammatory markers.

CONCLUSIONIBD patients have fecal flora imbalance compared with the healthy controls, and this imbalance may contribute to the occurrence and progression of IBD. The decline of Eubacterium contributes to the occurrence and development of IBD.

Adult ; Bacteria ; isolation & purification ; Bacteroides ; isolation & purification ; Bifidobacterium ; isolation & purification ; Biomarkers ; analysis ; Clostridium ; isolation & purification ; Colitis, Ulcerative ; microbiology ; Crohn Disease ; microbiology ; Enterococcus ; isolation & purification ; Eubacterium ; isolation & purification ; Feces ; microbiology ; Female ; Humans ; Inflammatory Bowel Diseases ; etiology ; microbiology ; Lactobacillus ; isolation & purification ; Male ; Peptococcus ; isolation & purification ; Saccharomyces ; isolation & purification