MICROENCAPSULATION OF YEAST-CELLS AND THEIR USE AS A BIOCATALYST IN ORGANIC-SOLVENTS

Stable, semipermeable polyamide microcapsules were prepared by interfa cial polymerization from a mixture of 1,6-hexanediamine and poly(allyl amine) crosslinked with di-acid chlorides and were used to encapsulate baker's yeast. The size and distribution of cells within the capsules were investigated by a combination of laser confocal, electron scanni ng, and transmission electron microscopy. The encapsulated cells were studied as a biocatalyst for the model reduction of 1-phenyl-1,2-propa nedione to 2-hydroxy-1-phenyl-1-propanone in a number of organic solve nts. The polymerization conditions were extensively investigated and w ere found to greatly influence the product yield. Microencapsulated ye ast cells, prepared under optimized conditions, carried out the reduct ion more efficiently than free cells as well as those immobilized in a lginate and kappa-carrageenan beads. The developed methodology should be broadly applicable to other biotransformations of interest. (C) 199 6 John Wiley & Sons, Inc.