一株产淀粉酶中度嗜盐菌Nesterenkonia sp.DQ-1的分离鉴定

利用平板筛选法从大庆盐碱地土壤中筛选到一株产淀粉酶并能在广泛NaCl浓度范围(0～25%)和广泛pH值范围(pH值为6～10)生长的耐盐碱菌DQ-1,对其进行形态学、生理生化鉴定和16SrDNA序列分析,DQ-1呈球形,大小约为0.5～0.8μm,最适培养条件为:NaCl 3%,30℃,pH=7.5;同源性比对结果表明,该菌株与多种涅斯捷连科氏菌的16SrDNA序列同源性高达99%。结合生理生化指标,初步确定DQ-1菌株可能是耐盐涅斯捷连科氏菌属的一个亚种。DQ-1产生的淀粉酶最佳反应条件为NaCl 2%、pH值在7～7.5、温度40℃,酶在0～12%的NaCl中具有活性,在pH值为5～12不失活,说明DQ-1产生的淀粉酶是一种能广泛耐盐碱的极端酶。

Isolation and characterization of a moderately halophilic bacterium Nesterenkonia sp.DQ - 1

An alkaliphilic and halophilic bacterium,DQ-1,which can survive under wide range of NaCl concent ration(0~25%) and pH(6~10),was isolated from the saline-alkali soil of Daqing by plate method.Through study on its morphological,physiological and biochemical characteristics as well as 16SrDNA sequence homology comparison.The cells of DQ-1 are rods,diameter about 0.5~0.8 μm,the optimum growth conditions are 3% NaCl,30 ℃,pH=7.5.The homology analysis showed that 16SrDNA homologies was 99% between strain DQ-1 and many kinds of Nesterenkonia bacteriums.The phylogenetic tree showed that the relationship between strain DQ-1 and Nesterenkonia bacterium was the closest.Combination analysis of physiological and biochemical the strain DQ-1 was identified as a subspecies of salt-tolerant Nesterenkonia.The optimal reaction condition for DQ-1 strain amylase was NaCl at 2%,pH value of 7~7.5 and temperature of 40 ℃.The amylase was still activity at 2% NaCl and pH is 5~12.The amylase produced by DQ-1 strain was an extreme enzyme with saline-alkali widely.