Anoxybacillus beppuensis TSSC-1 (GenBank Number, EU710556), a thermophilic bacterium isolated from a hot spring reservoir, was found to optimally secrete a monomeric a-amylase at 55 degrees C and pH 7. The enzyme was purified to homogeneity by a single-step purification on phenyl sepharose 6FF, achieving a 58% yield, 10,000 U/mg specific activity and 19.5 fold purification. The molecular weight, K-m and V-max were 43 kD, 0.5 mg ml(-1) and 3571.42 mu mol ml(-1) m(-1), respectively. The enzymatic catalysis of soluble starch was optimum at 80 degrees C and pH 7. The thermodynamic parameters, K-d, t(1/2), Delta H*, Delta S*, E and Delta G*, were consistent. The very compact structure of the enzyme and the transitional enzyme-substrate complex resisted denaturation at extreme temperatures and alkaline pH. The K-d and t(1/2) measurements were consistent with the high thermostability and pH tolerance observed. The structural stability of the enzyme was also reflected by the values of Delta H*, Delta S*, E and Delta G*. While the enzyme did not exhibit metal ion dependency, it was resistant to chemical denaturation. The broad thermo- and pH-tolerance of this enzyme suggests potential commercial opportunities. (C) 2012 Elsevier Ltd. All rights reserved.