黄颡鱼溶酪巨型球菌的鉴定与药敏试验

Identification and Drug Sensitivity of Megasphaera from Yellow Catfish Pelteobagrus fulvidraco

自患病黄颡鱼中分离出一株优势菌HS1,根据细菌形态学观察、生理生化、16SrDNA基因序列分析、动物回感试验及药敏试验等方法对其菌株进行研究。试验结果表明,菌株HS1为动力阳性,革兰氏阴性球菌。扩增的16SrDNA序列大小为1466bp,登录号为KP191046,与溶酪巨型球菌同源性超过99%,进化树上与溶酪巨型球菌聚为一支,从而可判定HS1为溶酪巨型球菌。用溶酪巨型球菌HS1感染健康黄颡鱼,发现该菌具有较强的致病性。药敏试验表明,该菌对四环素、米诺环素和强力霉素等11种药物敏感,对复方新诺明、甲氧苄啶和氨磺甲基异恶唑3种药物耐药。这为黄颡鱼巨型球菌病的预防和治疗提供科学参考。

A strain of dominant bacterial HS1 was isolated from diseased yellow catfish Pelteobagrus f ul-vidraco ,then it was studied by biochemical characteristics ,16S rDNA gene sequences and drug sensitivity test .The results showed that HS1 was identified as obligate anaerobic ,power positive ,Gram -negative Cocci with optimum growth temperature of 28 ℃ .When the ethanol concentration was 2 .8% （v7） ,its growth was inhibited ,which resulted in an increase in turbidity and unpleasant sensory changes in beer . According to the analysis of 16S rDNA gene sequence ,the fragment size was 1466 bp with accession num-ber of KP191046 .Strain HS1 comprised sequences more related to Macrococcus caseolyticus （99% homol-ogy） ,which showed that strain HS1 is M .caseolyticus .Strain HS1 was sensitive to tetracyclines ,amin-oglycosides ,amphenicols ,quinolones ,andβ-lactams ,while it was resistant to sulfa-drugs .The findings provide a scientific reference with the prevention and treatment of M .caseolyticus infection in fish .