Partition and substrate concentration effect in the enzymatic synthesis of cephalexin in aqueous two-phase systems

Is enzyme immobilization a mature discipline? Some critical considerations to capitalize on the benefits of immobilization

“…237 They are especially suitable for extraction of hydrophilic compounds, where conventional organic solvent-aqueous biphasic systems cannot be employed. [238][239][240][241][242][243] By extracting the reaction product, the concomitant product modification may be reduced (e.g., hydrolysis of the product in kinetically controlled synthesis) or the reaction equilibrium shifted to the product. [237][238][239][240][241]244 In such systems, the soluble enzyme may be in both phases although not at identical concentrations, since it may also suffer partition.…”

“…[238][239][240][241][242][243] By extracting the reaction product, the concomitant product modification may be reduced (e.g., hydrolysis of the product in kinetically controlled synthesis) or the reaction equilibrium shifted to the product. [237][238][239][240][241]244 In such systems, the soluble enzyme may be in both phases although not at identical concentrations, since it may also suffer partition. In fact, such biphasic systems may even be used for protein fractionation and purification.…”

“…237 They are especially suitable for extraction of hydrophilic compounds, where conventional organic solvent-aqueous biphasic systems cannot be employed. 238–243 By extracting the reaction product, the concomitant product modification may be reduced ( e.g. , hydrolysis of the product in kinetically controlled synthesis) or the reaction equilibrium shifted to the product.…”

Recovery of Biological Products in Aqueous Two Phase Systems

“…More examples of extractive bioconversion in two-phase systems are presented in Table 2. Cultivation of Polyporus squamosus in PEG and crude dextran for production of pectinase [15] Hydrolysis of starch using amylase in thermoseparating polymer-based aqueous two-phase systems [50] Bioconversion of cellulose by Trichoderma viride in dextran and polyethylene glycol (PEG) system [51] Synthesis of cephalexin by using penicillin G acylase in PEG-magnesium sulfate system [52] Bioconversion of penicillin G to 6-aminopenicillanic acid (6-APA) in ATPS consisting of PEG and potassium phosphate solution [53] Production of xylanase by the thermophilic fungus Paecilomyces thermophila J18 in solid-state fermentation using ATPS [54] Production of pectinases by Polyporus squamosus in aqueous two-phase system (PEG-crude dextran) [55] The use of ATPS for simultaneous biosynthesis and purification of two extracellular Bacillus hydrolases [56] The extractive bioconversion in ATPSs has also overcome the degradation of product such as the production of antibiotic decrease after closing maximum bioconversion due to the prevalence of product degradation over synthesis [57]. Furthermore, the subsequent downstream processing steps are probably eliminated in number as it is an integration of product removal with that of bioconversion.…”

Efficient enzymatic synthesis of cephalexin in suspension aqueous solution system

“…To improve the efficiency of penicillin G acylase‐catalyzed synthesis of CEX based on the kinetically controlled method, great efforts have been made by researchers in the past decades: optimization of reaction pH and temperature [9–12], use of cosolvents to reduce the water activity [13–16], in situ product removal by an aqueous two‐phase system [17–20] or complexation [21,22], modification of the catalytic properties of the enzyme [23–25], utilization of highly condensed systems without the aqueous phase [26], as well as control of reactant concentrations [27–32]. The latter has been extensively studied, and it is demonstrated that high concentrations of reactants are beneficial to the conversion ratio and productivity.…”