A highly thermostable amylase from a newly isolated thermophilicBacillussp. WN11

A thermostable amylase‐producing Bacillus sp. WN11 was isolated from Wondo Genet hot spring in Ethiopia. The enzyme had a temperature optimum of 75–80 °C. Over 80% of its peak activity was in the pH range of 5–8, with an optimum at 5·5. Thermal stability of the enzyme at 105 °C was higher with the addition of starch. The stabilizing effect of starch was concentration‐dependent, showing better stability with increasing concentration of starch. At liquefying temperature (105 °C), addition of Ca2+ did not result in further improvement of the stabilizing effect of starch. This indicates that in the presence of starch, WN11 amylase does not require Ca2+ as a stabilizer at liquefying temperatures as high as 105 °C.