Identification of an Acidic Bacterial Strain Producing α-amylase and the Optimization of Its Fermentation Condition

[Objective]The basis of the value of an acidic bacteria strain-B-5 of α-amylase-producing was further laid through the study on its high-yielding fermentation characteristics and its identification.[Method]The strain-B-5 being taken as the research object,its identification was done through the morphology,colony characteristics,physiological and biochemical characteristics and the analysis of 16S rDNA homology.The best fermentation condition of the strain was determined based on the optimum culture medium through the method of single-factor method and orthogonal test.[Results]The bacteria strain was identification as bacillus(Bacillus sp.) with the traditional method and molecular biological method.With soluble starch,corn flour or wheat flour as a carbon source,the strain-B-5 contributed to enzyme-producing.From the viewpoint of the cost reduction in industrial production,the corn flour could be adopted as a carbon source in its fermentation.And the tryptone was selected as nitrogen source because the highest activity of enzyme in its fermentation was produced by the nitrogen source.The orthogonal experiment results showed that it was most conducive to fermentation when the component of corn flour and tryptone in medium was 2%,respectively,with the activity of enzyme of 74.6 U/ml.The highest activity of enzyme in the B-5 fermentation appeared at the treatment time of 60th hour and the activity of enzyme was gradually decreased with time-lasting.[Conclusion]The activity of the enzyme of strain-B-5 was still limited,which yet could not meet the needs of industrial production,although nature of the acidic α-amylase produced by the strain was excellent.It was beneficial to the production of the bacteria strain of acidic α-amylase-producing for its industrialization through the identification of the gene in the strain.