Alperi Anabel, Figueras Maria J, Inza Isabel, Martínez-Murcia Antonio J
Department of Microbiology, Rovira Virgili University, Reus, Spain.
Int Microbiol. 2008 Sep;11(3):185-94.
Characterization of 999 Aeromonas strains using a published 16S rDNA RFLP identification method showed that 8.1% of the strains produced unexpected (hereafter called "atypical") restriction patterns, making their identification uncertain. Atypical patterns were due to the presence of nucleotide polymorphisms among the rrn operons of the 16S rRNA gene (so-called microheterogeneities). Double sequencing signals at certain positions revealed the nucleotide composition was responsible for the microheterogeneities. Although the number of microheterogeneities was relatively low (0.06-0.66%), trees inferred from the 16S rRNA gene led either to a misidentification or to an inconclusive result for the majority of these strains. Strains with atypical patterns were, however, correctly identified using the rpoD gene sequences, as belonging to Aeromonas caviae, A. veronii, and A. media. All of them, but particularly the two former species, are associated with human disease. Microheterogeneities in 16S rRNA gene sequence were significantly (P 0.01) more prevalent in clinical than in environmental strains. This work also analyzed the effects of these microheterogeneities on the taxonomic position of the investigated strains. The results suggest the need for recording microheterogeneities in the 16S rRNA gene.
使用已发表的16S rDNA RFLP鉴定方法对999株气单胞菌菌株进行鉴定，结果显示8.1%的菌株产生了意外（以下称为“非典型”）的限制性图谱，导致其鉴定结果不确定。非典型图谱是由于16S rRNA基因的rrn操纵子之间存在核苷酸多态性（即所谓的微异质性）。某些位置的双测序信号显示核苷酸组成是微异质性的原因。尽管微异质性的数量相对较少（0.06 - 0.66%），但从16S rRNA基因推断的系统发育树对大多数这些菌株要么导致错误鉴定，要么得出不确定的结果。然而，具有非典型图谱的菌株使用rpoD基因序列被正确鉴定为豚鼠气单胞菌、维氏气单胞菌和中间气单胞菌。所有这些菌株，尤其是前两个物种，都与人类疾病有关。16S rRNA基因序列中的微异质性在临床菌株中比在环境菌株中显著（P < 0.01）更普遍。这项工作还分析了这些微异质性对所研究菌株分类地位的影响。结果表明需要记录16S rRNA基因中的微异质性。
