| Vibrios are widely distributed in multiple natural environment, and closely related to human health andbursts of aquacultural animal diseases. Multiplicity of16S rRNA gene exsists within a single Vibrio genome, andheterogeneity occurs among copies. The multiplicity and heterogeneity of16S rRNA gene within a single Vibriogenome may be corresponding to its ecological adaptation.In this study,27Vibrio strains, which belong to Vibrio core group-harveyi group, were investigated. Firstly,they were phylogenetically difined into three species named Vibrio alginolyticus, V. harveyi and V. campbellii,according to the identification by16S rRNA, pyrH, rpoA and recA genes.Then, their16S rRNA gene copy number was estimated by both absolute and relative real-time quantativePCR. It was clearly showed that the estimated16S rRNA gene copy number of V. harveyi ATCC BAA-1116was11, which equaled to the data documented in rrNDB database. Copy number of V. harveyi ATCC14126T, V.alginolyticus ATCC17749Tand V. campbellii ATCC25920Twas9,11and9, respectively. Copy numbers variedwithin the three species respectively, with V. harveyi ranging from9to13, V. alginolyticus ranging from10to13,while V. campbellii ranging from9to11.Finally, a clone library containing16S-ITS rDNA sequences of V. alginolyticus ATCC17749Twasconstructed. There were11kinds of ITS sequences based on alignment, and11OTUs of16S-ITS rDNAsequences by Msp I or Hha I restriction analysis, which demonstrated the exsistence of11copies and thus inaccordance with the qPCR result. According to alignment of sequenced representative clones, difference among16S rDNA copies was found to be less than1%, and mainly concentrated in V3region with an exception whosedifference located in V7region. Since they were stem loops revealed by the sencondary structure, thehypervariable regions may correlate with the environmental adaptation especially that of a high sanility. ITSdiffered by their length and similarity, but may conserve by functions. |
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