title: A highly thermoactive and salt-tolerant α-amylase isolated from a pilot-plant biogas reactor.
abstract: Aiming at the isolation of novel enzymes from previously uncultured thermophilic microorganisms, a metagenome library was constructed from DNA isolated from a pilot-plant biogas reactor operating at 55 °C. The library was screened for starch-degrading enzymes, and one active clone was found. An open reading frame of 1,461 bp encoding an α-amylase from an uncultured organism was identified. The amy13A gene was cloned in Escherichia coli, resulting in high-level expression of the recombinant amylase. The novel enzyme Amy13A showed the highest sequence identity (75%) to α-amylases from Petrotoga mobilis and Halothermothrix orenii. Amy13A is highly thermoactive, exhibiting optimal activity at 80 °C, and it is also highly salt-tolerant, being active in 25% (w/v) NaCl. Amy13A is one of the few enzymes that tolerate high concentrations of salt and elevated temperatures, making it a potential candidate for starch processing under extreme conditions.
authors: Institute of Technical Microbiology, Hamburg University of Technology, Kasernenstr. 12, Hamburg, 21073, Germany. jabbour@msu.edu
authors: Dina
authors: D
authors: Jabbour
authors: Anneke
authors: A
authors: Sorger
authors: Kerstin
authors: K
authors: Sahm
authors: Garabed
authors: G
authors: Antranikian
mesh_terms: D000595:Amino Acid Sequence; D056804:Biofuels; D019149:Bioreactors; D003001:Cloning, Molecular; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D054892:Metagenome; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D056804:Biofuels; D011994:Recombinant Proteins; D012965:Sodium Chloride; D013213:Starch; D000516:alpha-Amylases