초록
<P><B>Abstract</B></P> <P>The industrial importance of optically pure compounds has thrown a spotlight on ω-transaminases that have shown a high potential for the synthesis of bioactive compounds with a chiral amine moiety. The implementation of biocatalysts in industrial processes relies strongly on fast and cost effective process development, including selection of a biocatalyst form and the strategy for its immobilization. Here, microscale reactors with selected surface-immobilized amine-transaminase (ATA) in various forms are described as platforms for high-throughput process development. Wild type ATA (ATA-wt) from a crude cell extract, as well as <I>Escherichia coli</I> cells intracellularly overexpressing the enzyme, were immobilized on the surfaces of meander microchannels of disposable plastics by means of reactor surface silanization and glutaraldehyde bonding. In addition, a silicon/glass microchannel reactor was used for immobilization of an ATA-wt, genetically engineered to contain a silica-binding module (SBM) at the N-terminus (N-SBM-ATA-wt), leading to immobilization on the non-modified inner microchannel surface. Microreactors with surface-immobilized biocatalysts were coupled with a quenching system and at-line HPLC analytics and evaluated based on continuous biotransformation, yielding acetophenone and <SMALL>L</SMALL>-alanine. <I>E. coli</I> cells and N-SBM-ATA-wt were efficiently immobilized and yielded a volumetric productivity of up to 14.42 g L<SUP>−1</SUP> h<SUP>−1</SUP>, while ATA-wt small load resulted in two orders of magnitude lower productivity. The miniaturized reactors further enabled <I>in-operando</I> characterization of biocatalyst stability, crucial for successful transfer to a production scale.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microreactors with various forms of immobilized amine-transaminase were developed. </LI> <LI> Integrated quenching and HPLC analytics enabled fast reactor performance evaluation. </LI> <LI> Covalent binding of <I>E. coli</I> cells with ATA-wt to surface was very efficient. </LI> <LI> The N-SBM-ATA-wt in a glass/silicon channel provided the highest productivity. </LI> <LI> <I>In-operando</I> characterization of immobilization stability was performed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>