The Study Of Intestinal Bacterial Molecular Ecology Of Cultured Fishes

The gastrointestinal microbiota of fish is characterized by its high population density, wide diversity and complexity of interactions. Importantly, GI microbes have a profound influence on nutritional, physiological and immunological processes in the host. Recently, findings from culture-based methods have been supplemented with molecular ecology techniques that are based on the 16S rRNA gene. These techniques enable characterization and quantification of the microbiota, and also provide a classification scheme to predict phylogenetic relationships. Microbial community structure can be analyzed via fingerprinting techniques. For analyzing the influence factors of bacterial community structural in intestinal tract of cultured fishes, this thesis aimed at it by using denaturing gradient gel electrophoresis (DGGE).Comparison and analysis of feed, sediment of pond, pond water, intestinal wall and contents of Carassius auratus from pond in Dafeng and Sheyang: the results showed that the gastrointestinal microbiota of Carassius auratus is affected by pond water, sediment of pond and feed, especially for pond water though the dgge fingerprint. Therefore, environmental factor is the main factor of influencing gastrointestinal microbiota of Carassius auratus by same feed condition.Comparison and analysis of different feed influencing gastrointestinal microbiota of Ctenopharyngodon idellus: gastrointestinal microbiota of casing meal group is more abundance when protein source is casing meal or soybean meal, is likely to relate amino acid composing of different protein sources; gastrointestinal microbiota of Ctenopharyngodon idellus feed by different level lecithoid is accordant basically, more favorable for fat absord to facilitate growth sequentially but no obvious influence with gastrointestinal microbiota of Ctenopharyngodon idellus by adding lecithoid rapeseed meal; there is obvious influence with gastrointestinal microbiota of Ctenopharyngodon idellus by adding cottonseed meal or rapeseed meal singly; replacing partly Wheat middling and reddog by no or more proportion corn grain for energy source is obvious influential to gastrointestinal microbiota; different adding proportion of DDGS and malt root is not too obvious influence.The dominant autochthonous bacteria in the gastrointestinal tract of Carassius auratus belonged to Actinobacteria, Proteobacteria, Firmicutes, Fusobacteria and Unclassified Bacteria; and the dominant autochthonous bacteria of Ctenopharyngodon idellus belonged to Firmicutes, Proteobacteria, Actinobacteria, Cyanobacteria and Unclassified Bacteria followed reports basiclly, according to the 16S rDNA genes analysis and BLAST.