fa <p style="line-height:120%;layout-grid-mode:char;"><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">The formation and regulation of vertebrate endogenous intestinal microbiota has been widely studied as the microbiota plays a crucial role in the host nutrition, development, and health. Despite the importance of microbiota for host health, it is still unclear whether the endogenous intestinal microorganisms are genetically distinct or whether they are genetically related with each other in different host individuals. In the present study, the dispersal situation of the endogenous intestinal bacteria in grass carp was investigated by constructing bacterial 16S rRNA gene clone libraries. The results indicate that the bacteria harbored in the grass carp gut could be separated into the following two groups: a- the private operational taxonomic units (OTUs)</span></span><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">, which include <em>Cetobacterium somerae</em></span></span><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">, </span></span><em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">Aeromonas jandaei</span></span></em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">, </span></span><em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">Citrobacter freundii</span></span></em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">, </span></span><em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">Achromobacter xylosoxidans</span></span></em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;"> and </span></span><em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">Bacteroides</span></span></em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;"> species; b- the shared OTUs, which include</span></span> <em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">Vibrio cholerae</span></span></em><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">, <em>Plesiomonas shigelloides</em> and <em>Pasteurella</em> speices. The results obtained in this investigation provide valuable information for assessing the mechanism of spread of the </span></span><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;">endogenous</span></span><span style="font-family:times new roman,serif;"><span style="font-size:12.0pt;"> intestinal bacteria, especially the pathogenic ones. However, the mechanisms involved in different modes of bacterial dispersal in the grass carp gut still require further research.</span></span></p> Dispersal barrier, Intestinal bacteria, Clone library, Grass carp 605 618 http://jifro.ir/browse.php?a_code=A-10-600-76&slc_lang=fa&sid=1 J.J. Ni 100319475328460021743 100319475328460021743 No Q.Y. Yan 100319475328460021744 100319475328460021744 No Y.H. Yu yhyu@ihb.ac.cn 100319475328460021745 100319475328460021745 Yes H.H. Wu 100319475328460021746 100319475328460021746 No F. Chen 100319475328460021747 100319475328460021747 No