Ucko Michal, Colorni Angelo, Dubytska Lidiya, Thune Ronald L
Israel Oceanographic and Limnological Research, National Center for Mariculture, PO Box 1212, Eilat 88112, Israel.
Dis Aquat Organ. 2016 Sep 26;121(2):141-148. doi: 10.3354/dao03051.
An Edwardsiella sp. was isolated from the kidney of diseased groupers (Epinephelus aeneus and E. marginatus) cultured in Eilat (Israel, Red Sea). Affected fish presented a severe suppurative nephritis with large abscesses occasionally spreading into the surrounding musculature. Biochemical profiles and phenotypic comparisons failed to provide a clear identification to the species level, and genetic analysis of the 16S subunit failed to discriminate between Edwardsiella piscicida, E. tarda and E. ictaluri. Analysis of the gyrB gene, however, placed the grouper isolates into the E. piscicida-like group, a newly recognized taxon which also encompasses the non-motile strains previously classified as atypical E. tarda. Initial genomic analysis revealed the presence of the Edwardsiella type 3 secretion system (T3SS) but also revealed a pathogenicity island encoding a second T3SS with homology to the locus of enterocyte effacement of Escherichia coli. Further analysis revealed 3 different type 6 secretion systems that were also present in all sequenced isolates of Edwardsiella piscicida-like strains. Based on estimated DNA-DNA hybridization values and the average nucleotide index, the grouper strain fits into the E. piscicida-like phylogroup described as E. anguillarum sp. nov. The peculiarities associated with this isolate and the association of other conspecific piscine isolates from multiple marine and brackish water species suggest a link of the entire E. piscicida-like phylogroup to the marine environment.
从在埃拉特(以色列,红海)养殖的患病石斑鱼(巨石斑鱼和镶边石斑鱼)的肾脏中分离出一株爱德华氏菌属细菌。患病鱼呈现出严重的化脓性肾炎,伴有大脓肿,偶尔会扩散到周围肌肉组织。生化特征和表型比较未能明确鉴定到种水平,16S亚基的基因分析也无法区分杀鱼爱德华氏菌、迟缓爱德华氏菌和鲶鱼爱德华氏菌。然而,gyrB基因分析将石斑鱼分离株归入杀鱼爱德华氏菌样组,这是一个新认可的分类单元,其中还包括以前被归类为非典型迟缓爱德华氏菌的不运动菌株。初步基因组分析显示存在爱德华氏菌3型分泌系统(T3SS),但也揭示了一个致病岛,该致病岛编码第二个T3SS,与大肠杆菌肠细胞脱落位点具有同源性。进一步分析发现,所有测序的杀鱼爱德华氏菌样菌株分离株中都存在3种不同的6型分泌系统。根据估计的DNA-DNA杂交值和平均核苷酸指数,石斑鱼菌株属于被描述为鳗弧菌新种的杀鱼爱德华氏菌样系统发育组。与该分离株相关的特性以及来自多种海洋和咸淡水物种的其他同种鱼类分离株的关联表明,整个杀鱼爱德华氏菌样系统发育组与海洋环境存在联系。