title: Overcoming hydrolysis of raw corn starch under industrial conditions with Bacillus licheniformis ATCC 9945a α-amylase.
abstract: α-Amylase from Bacillus licheniformis ATCC 9945a (BliAmy) was proven to be very efficient in hydrolysis of granular starch below the temperature of gelatinization. By applying two-stage feeding strategy to achieve high-cell-density cultivation of Escherichia coli and extracellular production of BliAmy, total of 250.5 U/mL (i.e. 0.7 g/L) of enzyme was obtained. Thermostability of amylase was exploited to simplify purification. The hydrolysis of concentrated raw starch was optimized using response surface methodology. Regardless of raw starch concentration tested (20, 25, 30 %), BliAmy was very effective, achieving the final hydrolysis degree of 91 % for the hydrolysis of 30 % starch suspension after 24 h. The major A-type crystalline structure and amorphous domains of the starch granule were degraded at the same rates, while amylose-lipid complexes were not degraded. BliAmy presents interesting performances on highly concentrated solid starch and could be of value for starch-consuming industries while response surface methodology (RSM) could be efficiently applied for the optimization of the hydrolysis.
authors.affiliation: Centre of Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Studentski trg 12-16, Belgrade, 11000, Serbia.
authors.forename: Marinela
authors.initials: M
authors.lastname: Šokarda Slavić
authors.affiliation: Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade, 11000, Serbia.
authors.forename: Milja
authors.initials: M
authors.lastname: Pešić
authors.affiliation: Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade, 11000, Serbia.|Center of Excellence for Molecular Food Sciences, University of Belgrade, Studentski trg 12-16, Belgrade, 11000, Serbia.
authors.forename: Zoran
authors.initials: Z
authors.lastname: Vujčić
authors.affiliation: Centre of Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Studentski trg 12-16, Belgrade, 11000, Serbia. nbozic@chem.bg.ac.rs.
authors.forename: Nataša
authors.initials: N
authors.lastname: Božić
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D001711:Biotransformation; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D013213:Starch / Q000378:metabolism*; D003313:Zea mays / Q000378:metabolism*; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D013213:Starch; D000516:alpha-Amylases
keywords: Amylase; Bacillus sp.; Fed-batch; Purification; Raw starch degradation; Statistical experimental design