本研究从泥鳅养殖水体、底泥、健康泥鳅和患病泥鳅肠道等环境中采集样品,从中分离纯化出对凡隆气单胞菌具有拮抗作用的细菌57株.在TSB平板上采用牛津杯法进行体外拮抗实验,筛选出一株对凡隆气单胞菌具有明显拮抗作用的菌株CMA-1,经形态观察、生理生化鉴定和16SrDNA序列系统发育分析,将该菌鉴定并命名为Bacillus methylotrophicus CMA-1.菌株CMA-1生长24 h后进入稳定期,36 h时发酵上清液抑菌活性达到最大.对菌株CMA-1的发酵上清液采用硫酸铵分级沉淀,测得75％硫酸铵饱和度下的沉淀粗提物抑菌活性最高.%Aeromonas veronii is a kind of pathogenic microorganisms found in the intestinal tract of loach Misgurnus anguillicaudatus , and may result in 60% high mortality. Here, 57 antagonistic bacteria strains against A. veronii were isolated from the samples collected from aquaculture water, sludge and intestine of healthy and sick loaches. Their antibacterial activities were examined by cylinder-plate method with TSB medium. A bacterial strain, named CMA-1, was screened from them and identified as Bacillus methylotrophicus CMA-1 by morphological observation, physiological characteristics tests, and 16S rDNA sequence analysis. The growth of CMA-1 entered into the stationary phase after being cultured for 24h ,and its antibacterial activity was up to the maximum at 36h. The crude metabolites were separated from fermentationrnbroth through ammonium sulfate precipitation, and their antibacterial activities were examined. The results showed that the antibacterial activity of precipitate at 75% (NH4)2SO4 saturation was significantly higher. CMA-1 would be a useful probiotics in the prevention and control of fish disease caused by A. veronii.
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