Isolation And Identification Of The Chicken Gut Microbiota And Investigation Of Their Effects On Host Health

Currently, the abuse of antibiotics in livestock and poultry industry has become a major security risk. In order to find the effective alternatives, the development and application of probiotics has been become one of the hot topics. In addition, the research related to the normal intestinal microflora also provide a new direction for the development of new probiotics in recent years. Some studies have found that in animal gut microflora system, the anaerobic bacteria accounted for more than99%. The aim of this study was to develop a functionally significant, tolerance strong and easy to cultured probiotics from the original anaerobic bacteria in the chicken gut microbiota.The first part of this research was to culture parts of the chicken gut microbes in vitro. Firstly, we isolated two Clostridium strains C1and B5, which have specific morphology and was identified as new Clostridium bacteria. We used DAPI staining and Gram staining to observe their specific shape and found they varied greatly each other. Although the physiological and biochemical test results showed that they both are Clostridium, their specific classification need further study. The tests in vitro found that the Clostridium C1has no inhibition effects on Salmonella growth. Secondly, we used an in vitro modeling (chemostat system) to ferment the cecal contents of an adult chicken. We obtained a mature and stable chicken intestinal flora detected by using PCR-DGGE.Based on these results, we further investigated the effects of these intestinal microbial on chicken health. We chose a lactic acid bacteria, Clostridium C1, a matured chicken intestinal flora and tetracycline to interfered the colonization of intestinal flora in newborn chicks. The chicks of positive control group were feed normally, and the interference sustained five days. After that, all chicks were intragastrically challenged with Salmonella. All chicks then were weighted weekly. Every week, parts of chicks from each group were dissected and the cecal contents were collected for further detection. The weight results showed that the difference between tetracycline group and Clostridium group is not significant, however, both groups were significant better than the positive control group(P<0.05). The viable Salmonella in lactic acid bacteria group, Clostridium group, fermentation group and tetracycline group were significant lower than the positive control group(P<0.05). We also found the fermentation group had a great effects on the colonization of chicks gut microbiota by using PCR-DGGE to detected the microbial community structure. The Q-PCR results showed that the major flora in chicken intestinal contents from each group had no obvious difference. In summary, this research showed that this lactic acid bacteria can inhibit the growth of Salmonella in vivo, however, it has no effects on the growth of chicks. Although, the Clostridium C1don’t have the effects on inhibit the growth of Salmonella in vivo, the animal protection experiment showed that the Clostridium C1can inhibit the colonization of Salmonella in vivo, and its growth-promoting effects is similar to tetracycline, which suggested that the Clostridium C1has a good effecrs on promote chicken growth. Fermentation products can accelerate the development of intestinal flora in chicks and inhibit the growth of Salmonella, however, its effects on growth-promoting are not obvious.