Isolation, Characterization Of A Novel Thermostable And Acidostable α-amylase From Alicyclobacillus Sendaiensis NUST

With the development of starch Proeessing industry more and more starch Proeessing technologies needα-amylase which could keep stable under low pH and high temperature conditions. A special enzyme, acidstable and thremostable amylase can be used in starch processing under low pH. The application of the enzyme can improve and modify the starch processing, reduce the cost of the Production and help to solve the disposal and pollution Problems etc. The objective of this study was the screening of a novel acidstable and thremostable amylase producing strain and the study of its enzyme charaters.A strain of thermostable and acidstableα-Amylase producing bacteria was sereened from pot ale of traditional Chinese wine. It is identified as Alicyclobacillus sendaiensis through determing its 16s rDNA sequence combined with biochemical and biophysical tests.A thermostable and acid toleranceα-amylase was isolated from Alicyclobacillus sendaiensis NUST. The enzyme was purified to homogeneity by ultrafiltration, ammonium sulphate precipitation, Sephadex G-100 gel filtration and DEAE-cellulose anion exchange chromatography. The enzyme was purificated to 6.8 fold with a yield of 5.1% finally.The molecular weight of this enzyme was estimated to be 65kd by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme had maximal activity at pH 3.5 and 85℃in the presence of soluble starch as substrate. The enzyme was not Ca²⁺ dependent and was highly active and stable in acid conditions.