title: Amylase partitioning and extractive bioconversion of starch using thermoseparating aqueous two-phase systems.
abstract: The effectiveness of thermoseparating polymer-based aqueous two-phase systems (ATPS) in the enzymatic hydrolysis of starch was investigated. In this work, the phase diagrams of PEO-PPO-2500/ammonium sulfate and PEO-PPO-2500/magnesium sulfate systems were determined at 25 degrees C. The partition behavior of pure alpha-amylase and amyloglucosidase in four ATPS, namely, PEO-PPO/(NH(4))(2)SO(4), PEO-PPO/MgSO(4), polyethylene glycol (PEG)/(NH(4))(2)SO(4), and PEG/MgSO(4), was evaluated. The effects of phase-forming component concentrations on the enzyme activity and partitioning were assessed. Partitioning of a recombinant, thermostable alpha-amylase (MJA1) from the hyperthermophile, Methanococcus jannaschii was also investigated. All of the studied enzymes partitioned unevenly in these polymer/salt systems. The PEO-PPO-2500/MgSO(4) system was extremely attractive for starch hydrolysis. Polymer-based starch hydrolysis experiments containing PEO-PPO-2500/MgSO(4) indicated that the use of ATPS had a significant effect on soluble starch hydrolysis. Batch starch hydrolysis experiments with PEO-PPO/salt two-phase systems resulted in higher production of maltose or glucose and exhibited remarkably faster hydrolysis. A 22% gain in maltose yield was obtained as a result of the increased productivity. This work is the first reported application of thermoseparating polymer ATPS in the processing of starches. These results reveal the potential for thermoseparating polymer-enhanced extractive bioconversion of starch as a practical technology.
authors.affiliation: Department of Chemical and Biochemical Engineering, The University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Mian
authors.initials: M
authors.lastname: Li
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Kim
authors.forename: Tonya L
authors.initials: TL
authors.lastname: Peeples
mesh_terms: D001709:Biotechnology; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D005087:Glucan 1,4-alpha-Glucosidase / Q000302:isolation & purification / Q000378:metabolism; D005947:Glucose / Q000302:isolation & purification / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008320:Maltose / Q000302:isolation & purification / Q000378:metabolism; D017017:Methanococcus / Q000201:enzymology / Q000235:genetics; D012995:Solubility; D013213:Starch / Q000302:isolation & purification* / Q000378:metabolism*; D013696:Temperature; D014867:Water; D000516:alpha-Amylases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D014867:Water; D008320:Maltose; D013213:Starch; D000516:alpha-Amylases; D005087:Glucan 1,4-alpha-Glucosidase; D005947:Glucose