Watanabe Noboru, Morita Koji, Furukawa Tomoko, Manzoku Taki, Endo Eiko, Kanamori Masato
Department of Microbiology, Kyorin University School of Health Sciences, Tokyo 192-8508, Japan.
Appl Environ Microbiol. 2004 Jan;70(1):145-51. doi: 10.1128/AEM.70.1.145-151.2004.
DNA fragments were amplified by PCR from all tested strains of Aeromonas hydrophila, A. caviae, and A. sobria with primers designed based on sequence alignment of all lipase, phospholipase C, and phospholipase A1 genes and the cytotonic enterotoxin gene, all of which have been reported to have the consensus region of the putative lipase substrate-binding domain. All strains showed lipase activity, and all amplified DNA fragments contained a nucleotide sequence corresponding to the substrate-binding domain. Thirty-five distinct nucleotide sequence patterns and 15 distinct deduced amino acid sequence patterns were found in the amplified DNA fragments from 59 A. hydrophila strains. The deduced amino acid sequences of the amplified DNA fragments from A. caviae and A. sobria strains had distinctive amino acids, suggesting a species-specific sequence in each organism. Furthermore, the amino acid sequence patterns appear to differ between clinical and environmental isolates among A. hydrophila strains. Some strains whose nucleotide sequences were identical to one another in the amplified region showed an identical DNA fingerprinting pattern by repetitive extragenic palindromic sequence-PCR genotyping. These results suggest that A. hydrophila, and also A. caviae and A. sobria strains, have a gene encoding a protein with lipase activity. Homologs of the gene appear to be widely distributed in Aeromonas strains, probably associating with the evolutionary genetic difference between clinical and environmental isolates of A. hydrophila. Additionally, the distinctive nucleotide sequences of the genes could be attributed to the genotype of each strain, suggesting that their analysis may be helpful in elucidating the genetic heterogeneity of Aeromonas.
通过PCR从所有测试的嗜水气单胞菌、豚鼠气单胞菌和温和气单胞菌菌株中扩增DNA片段，所用引物是根据所有脂肪酶、磷脂酶C、磷脂酶A1基因以及细胞紧张性肠毒素基因的序列比对设计的，所有这些基因都已报道具有假定脂肪酶底物结合域的共有区域。所有菌株均显示出脂肪酶活性，并且所有扩增的DNA片段都包含与底物结合域相对应的核苷酸序列。在来自59株嗜水气单胞菌菌株的扩增DNA片段中发现了35种不同的核苷酸序列模式和15种不同的推导氨基酸序列模式。来自豚鼠气单胞菌和温和气单胞菌菌株的扩增DNA片段的推导氨基酸序列具有独特的氨基酸，表明每种生物体中存在物种特异性序列。此外，嗜水气单胞菌菌株的临床分离株和环境分离株之间的氨基酸序列模式似乎有所不同。在扩增区域中核苷酸序列彼此相同的一些菌株通过重复外显子回文序列-PCR基因分型显示出相同的DNA指纹图谱模式。这些结果表明，嗜水气单胞菌以及豚鼠气单胞菌和温和气单胞菌菌株都有一个编码具有脂肪酶活性蛋白质的基因。该基因的同源物似乎广泛分布于气单胞菌菌株中，可能与嗜水气单胞菌临床分离株和环境分离株之间的进化遗传差异有关。此外，这些基因独特的核苷酸序列可归因于每个菌株的基因型，这表明对它们的分析可能有助于阐明气单胞菌的遗传异质性。
