Immobilization of Yeast Alcohol Dehydrogenase on Weakly Basic Anion Exchange Resin Beads

Yeast alcohol dehydrogenase was immobilized on weakly basic macroporous anion exchange resin beads Lewatit MP-64. After the adsorption the enzyme was crosslinked by glutaraldehyde: The activity of the immobilized enzyme was investigated in the pH 8.9 recirculation reactor system at 303 K. It was found that the immobilized enzyme was destabilized upon addition of semicarbazide hydrochloride to the buffer solution. A greater amount of protein was attached to the support when ethanol was present in the enzyme solution, but the activity of the bound enzyme was lower than in the absence of ethanol

White-rot fungi in phenols, dyes and other xenobiotics treatment – a brief review

Bioremediation is an attractive technology that utilizes the metabolic potential of microorganisms in order to clean up the environmental pollutants to the less hazardous or non-hazardous forms with less input of chemicals, energy and time. White-rot fungi are unique organisms that show the capacities of degrading and mineralizing lignin as well as organic, highly toxic and recalcitrant compounds. The key enzymes of their metabolism are extracellular lignolytic enzymes that enable fungi to tolerate a relatively high concentration of toxic substrates. This paper gives a brief review of many aspects concerning the application of white-rot fungi with the purpose of the industrial contaminants removal

Continuous enzymatic carboligation of benzaldehyde and acetaldehyde in an enzyme ultrafiltration membrane reactor and laminar flow microreactors

The synthesis of (S)-2-hydroxypropiophenone ((S)-2-HPP) from benzaldehyde and acetaldehyde catalyzed by benzoylformate decarboxylase (BFD) from Pseudomonas putida was studied in an enzyme ultrafiltration membrane reactor (UFMR) and in three different microreactors (MRs). The aim was to compare the volume productivity (QP) as well as biocatalyst productivity number (BPN) of these two continuous reactor systems. Influence of geometry, surface roughness of the microchannel walls, and inner mixing in the microreactors on conversion were also tested. In all used microreactors full conversion of benzaldehyde was achieved at residence times longer than 4 min. This was not the case in the UFMR where BFD was “soluble” immobilized because of the enzyme instability under the working conditions. The microreactor with inner mixing (micromixers) showed higher conversion at residence times shorter than 2 min (higher flow rates); while at longer residence times there were no significant differences between the different microreactor types. The biocatalyst productivity numbers of the microreactors were higher in comparison to the UFMR. The highest BPN was achieved in a microreactor with smooth surface microchannel walls (1.55 g g−1) at residence time of 5 min while the highest BPN in the UFMR (0.21 g g−1) was achieved at residence time of 30 min and 48 min of processing time

A cascade reaction for the synthesis of d-fagomine precursor revisited: Kinetic insight and understanding of the system

The synthesis of aldol adduct (3S,4R)-6-[(benzyloxycarbonyl)amino]-5,6-dideoxyhex-2-ulose, a precursor of the interesting dietary supplement, iminosugar d-fagomine, was studied in a cascade reaction with three enzymes starting from Cbz-N-3-aminopropanol. This system was studied previously using a statistical optimization method which enabled a 79 % yield of the aldol adduct with a 10 % yield of the undesired amino acid by-product. Here, a kinetic model of the cascade, including enzyme operational stability decay rate and the undesired overoxidation of the intermediate product, was developed. The validated model was instrumental in the optimization of the cascade reaction in the batch reactor. Simulations were carried out to determine the variables with the most significant impact on substrate conversion and product yield. As a result, process conditions were found that provided the aldol adduct in 92 % yield with only 0.7 % yield of the amino acid in a one-pot one-step reaction. Additionally, compared to previous work, this improved process outcome was achieved at lower concentrations of two enzymes used in the reaction. With this study the advantages are demonstrated of a modelling approach in developing complex biocatalytical processes. Mathematical models enable better understanding of the interactions of variables in the investigated system, reduce cost, experimental efforts in the lab and time necessary to obtain results since the simulations are carried out in silico.The authors wish to acknowledge the support of the Croatian Ministry of Science Education and Sports and the Spanish National Research Council in the Frame of the ERA-IB Project (EIB. 10.012.MicroTechEnz, ERA-IB MICINN PIM2010EEI-00607), the Ministerio de Economía y Competitividad (MINECO) and the Fondo Europeo de Desarrollo Regional (FEDER) (grant no. RTI2018-094637-B-I00).Peer reviewe