초록
<P><B>Abstract</B></P> <P>Crosslinked, cryostructured monoliths prepared from <I>Lactobacillus reuteri</I> cells were evaluated as potential immobilized whole-cell biocatalyst for conversion of glycerol, to potentially important chemicals for the biobased industry, i.e. 3-hydroxypropionaldehyde (3HPA), 3-hydroxypropionic acid (3HP) and 1,3-propanediol (1,3PDO). Glutaraldehyde, oxidized dextran and activated polyethyleneimine/modified polyvinyl alcohol (PEI/PVA) were evaluated as crosslinkers; the latter gave highly stable preparations with maintained viability and biocatalytic activity. Scanning electron microscopy of the PEI/PVA monoliths showed high density of crosslinked cells with wide channels allowing liquid flow through. Flux analysis of the propanediol-utilization pathway, incorporating glycerol/diol dehydratase, propionaldehyde dehydrogenase, 1,3PDO oxidoreductase, phosphotransacylase, and propionate kinase, for conversion of glycerol to the three chemicals showed that the maximum specific reaction rates were −562.6, 281.4, 62.4 and 50.5mg/g<SUB>CDW</SUB> h for glycerol consumption, and 3HPA (extracellular), 3HP and 1,3PDO production, respectively. Under optimal conditions using monolith operated as continuous plug flow reactor, 19.7g/L 3HPA was produced as complex with carbohydrazide at a rate of 9.1g/Lh and a yield of 77mol%. Using fed-batch operation, 1,3PDO and 3HP were co-produced in equimolar amounts with a yield of 91mol%. The monoliths embedded in plastic carriers showed high mechanical stability under different modes in a miniaturized plug flow reactor.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Lactobacillus reuteri</I> immobilization by crosslinking during cryostructuration. </LI> <LI> PEI/PVA gave stable monolith with maintained viability and biocatalytic activity. </LI> <LI> Determining metabolic fluxes from glycerol to 3HPA, 3HP and 1,3PDO in <I>Pdu</I> pathway. </LI> <LI> <I>L. reuteri</I> cryogel monolith operated in continuous and fed-batch modes of operation. </LI> <LI> Monolith embedded in plastic carriers showed high mechanical stability as plug flow. </LI> </UL> </P>