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【目的】对黄颡鱼水霉病病原进行分离鉴定,并对其药敏特性进行研究。【方法】参照传统方法对患水霉病的黄颡鱼卵上的丝状真菌进行分离,通过人工感染实验证实分离菌株的致病性,然后根据形态学特征和ITS rDNA序列分析对致病菌株进行鉴定,并进一步采用倍比稀释法研究其药敏特性。【结果】从患水霉病的黄颡鱼卵上分离到8株丝状真菌,经人工感染试验证实菌株YC对黄颡鱼卵具有致病性,并进一步研究了其形态与药敏特性,开展了ITS rDNA序列分析。结果表明,菌株YC为透明管状结构,中间无横隔;游动孢子囊多呈圆筒形、棍棒形或穗状,游动孢子发育成熟后不断从孢子囊顶端释放出来,成团聚集在游动孢子囊口,并经过一个时期的静休后,成团脱落或直接分散在水中游动;次生孢子囊具有典型的侧生现象;藏卵器呈球形或梨形,大多与雄器异枝,少数与雄器同枝,含1?15个卵孢子;成熟卵孢子中生或亚中生,偏生一个大油球。其ITS rDNA序列与GenBank基因库中绵霉属菌株自然聚类,同源性高达99%,与异丝绵霉(Achlya klebsiana)菌株CBS101.49(GenBank登录号AF119579)的亲缘关系最近。结合形态特征与ITS序列鉴定的结果,判定菌株YC为异丝绵霉(Achlya klebsiana)。此外,在实验选用的中草药和消毒剂中,黄连和异噻唑啉酮分别对菌株YC的抑菌效果最好,其对菌株YC的最小抑菌浓度分别为256 mg/L和2 mg/L。【结论】首次分离了黄颡鱼卵致病性异丝绵霉菌株YC,并确定了其药敏特性,可以作为该病防治用药的依据。
【Objective】 The objective of this study was to isolate and identify the pathogen of watery mildew in yellow catfish and study its drug sensitivity characteristics. 【Method】 The filamentous fungi isolated from the eggs of the catfish with moldy mildew were isolated by reference to the traditional methods. The pathogenicity of the isolates was confirmed by artificial infection experiments. The pathogenicity of the isolates was determined by morphological characteristics and ITS rDNA sequence analysis Identification, and further use of multiples dilution method to study the drug sensitivity characteristics. 【Result】 Eight strains of filamentous fungi were isolated from eggs of yellow catfish with watery mildew. The results of artificial infection test showed that strain YC was pathogenic to the eggs of yellow catfish and its morphology and drug sensitivity were further studied. ITS rDNA sequence analysis. The results showed that the strain YC was a transparent tubular structure with no transversal septum. The zoospore was mostly cylindrical, stick-shaped or spike. The zoospore released continuously from the top of the sporangium after it matured. After a period of rest, the cotyledons shed or directly disperse in the water. The secondary conidiophores have the typical lateral phenomenon. The ovipositor is spherical or pear-shaped, most of them are different from the male Branches, a few with the same branch with the male, containing 1? 15 oospores; mature oospores in the students or in the students, a large oil ball offset. ITS ITS sequence was 99% homologous to Genus Mucor in GenBank and the closest to GenBank accession number AF119579. According to the morphological characteristics and ITS sequence identification, strain YC was identified as Achlya klebsiana. In addition, the antibacterial effect of Coptis Chinensis and Isothiazolinone on the strain YC was the best among the herbs and disinfectants selected experimentally. The minimum inhibitory concentrations of Coptis chinensis and YC were 256 mg / L and 2 mg / L, respectively. 【Conclusion】 For the first time, YC, a strain of M. glabrata, was isolated and its drug sensitivity was determined, which can be used as the basis for the prevention and treatment of the disease.