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. 1985 May;49(5):1162–1167. doi: 10.1128/aem.49.5.1162-1167.1985

General Biochemical Characterization of Thermostable Extracellular β-Amylase from Clostridium thermosulfurogenes

H H Hyun 2, J G Zeikus 2,*
PMCID: PMC238523  PMID: 16346789

Abstract

Clostridium thermosulfurogenes, an anaerobic bacterium which ferments starch into ethanol at 62°C, produced an active extracellular amylase and contained intracellular glucoamylase but not pullulanase activity. The extracellular amylase was purified 2.4-fold, and its general physicochemical and catalytic properties were examined. The extracellular amylase was characterized as a β-amylase (1,4-α-d-glucan maltohydrolase) based on demonstration of exocleavage activity and the production of maltose with a β-anomeric configuration from starch. The β-amylase activity was stable and optimally active at 80 and 75°C, respectively. The pH optimum for activity and the pH stability range was 5.5 to 6 and 3.5 to 6.5, respectively. The apparent [S]0.5V and Vmax for β-amylase activity on starch was 1 mg/ml and 60 U/mg of protein. Similar to described β-amylase, the enzyme was inhibited by p-chloromercuribenzoate, Cu2+, and Hg2+; however, α- and β-cyclodextrins were not competitive inhibitors. The β-amylase was active and stable in the presence of air or 10% (vol/vol) ethanol. The β-amylase and glucoamylase activities enabled the organism to actively ferment raw starch in the absence of significant pullulanase or α-amylase activity.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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