Barony G M, Tavares G C, Assis G B N, Luz R K, Figueiredo H C P, Leal C A G
AQUAVET, Laboratory of Aquatic Animal Diseases, Veterinary School, Federal University of Minas Gerais, Belo Horizonte 30123-970, Brazil.
Dis Aquat Organ. 2015 Nov 17;117(1):1-11. doi: 10.3354/dao02931.
Flavobacterium columnare is responsible for disease outbreaks in freshwater fish farms. Several Brazilian native fish have been commercially exploited or studied for aquaculture purposes, including Amazon catfish Leiarius marmoratus × Pseudoplatystoma fasciatum and pacamã Lophiosilurus alexandri. This study aimed to identify the aetiology of disease outbreaks in Amazon catfish and pacamã hatcheries and to address the genetic diversity of F. columnare isolates obtained from diseased fish. Two outbreaks in Amazon catfish and pacamã hatcheries took place in 2010 and 2011. Four F. columnare strains were isolated from these fish and identified by PCR. The disease was successfully reproduced under experimental conditions for both fish species, fulfilling Koch's postulates. The genomovar of these 4 isolates and of an additional 11 isolates from Nile tilapia Oreochromis niloticus was determined by 16S rRNA restriction fragment length polymorphism PCR. The genetic diversity was evaluated by phylogenetic analysis of the 16S rRNA gene and repetitive extragenic palindromic PCR (REP-PCR). Most isolates (n = 13) belonged to genomovar II; the remaining 2 isolates (both from Nile tilapia) were assigned to genomovar I. Phylogenetic analysis and REP-PCR were able to demonstrate intragenomovar diversity. This is the first report of columnaris in Brazilian native Amazon catfish and pacamã. The Brazilian F. columnare isolates showed moderate diversity, and REP-PCR was demonstrated to be a feasible method to evaluate genetic variability in this bacterium.
柱状黄杆菌是淡水养鱼场疾病暴发的病原体。几种巴西本土鱼类已被商业化开发或用于水产养殖研究，包括亚马逊鲶鱼Leiarius marmoratus×Pseudoplatystoma fasciatum和帕卡马鲶Lophiosilurus alexandri。本研究旨在确定亚马逊鲶鱼和帕卡马鲶孵化场疾病暴发的病因，并研究从患病鱼中分离出的柱状黄杆菌菌株的遗传多样性。2010年和2011年，亚马逊鲶鱼和帕卡马鲶孵化场发生了两起疫情。从这些鱼中分离出4株柱状黄杆菌菌株，并通过PCR进行鉴定。在实验条件下，这两种鱼类都成功再现了疾病，满足了科赫法则。通过16S rRNA限制性片段长度多态性PCR确定了这4株分离株以及另外11株尼罗罗非鱼Oreochromis niloticus分离株的基因组型。通过对16S rRNA基因的系统发育分析和重复外显子回文PCR（REP-PCR）评估遗传多样性。大多数分离株（n = 13）属于基因组型II；其余2株分离株（均来自尼罗罗非鱼）被归为基因组型I。系统发育分析和REP-PCR能够证明基因组型内的多样性。这是巴西本土亚马逊鲶鱼和帕卡马鲶柱状病的首次报道。巴西的柱状黄杆菌分离株表现出中等程度的多样性，并且REP-PCR被证明是评估该细菌遗传变异性的一种可行方法。
