Cloning and characterization of two new thermostable and alkalitolerant α-amylases from the Anoxybacillus species that produce high levels of maltose

J Ind Microbiol Biotechnol. 2012 May;39(5):731-41. doi: 10.1007/s10295-011-1074-9. Epub 2012 Jan 14.

Abstract

Two genes that encode α-amylases from two Anoxybacillus species were cloned and expressed in Escherichia coli. The genes are 1,518 bp long and encode 506 amino acids. Both sequences are 98% similar but are distinct from other well-known α-amylases. Both of the recombinant enzymes, ASKA and ADTA, were purified using an α-CD-Sepharose column. They exhibited an optimum activity at 60°C and pH 8. Both amylases were stable at pH 6-10. At 60°C in the absence of Ca²⁺, negligible reduction in activity for up to 48 h was observed. The activity half-life at 65°C was 48 and 3 h for ASKA and ADTA, respectively. In the presence of Ca²⁺ ions, both amylases were highly stable for at least 48 h and had less than a 10% decrease in activity at 70°C. Both enzymes exhibited similar end-product profiles, and the predominant yield was maltose (69%) from starch hydrolysis. To the best of our knowledge, most α-amylases that produce high levels of maltose are active at an acidic to neutral pH. This is the first report of two thermostable, alkalitolerant recombinant α-amylases from Anoxybacillus that produce high levels of maltose and have an atypical protein sequence compared with known α-amylases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Anoxybacillus / enzymology*
  • Base Sequence
  • Cloning, Molecular
  • Enzyme Stability
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Hydrogen-Ion Concentration
  • Hydrolysis
  • Maltose / metabolism*
  • Starch / metabolism
  • Substrate Specificity
  • Temperature
  • alpha-Amylases / genetics
  • alpha-Amylases / metabolism*

Substances

  • Maltose
  • Starch
  • alpha-Amylases