Production of L-phenylacetylcarbinol (L-PAC) by encapsulated Saccharomycescerevisiae cells

In the present study, benzaldehyde was converted by both the free cells Sac charomyces cerevisiae (ATCC 834) and those immobilized in the calcium algin ate liquid-core capsule into L-PAC during anaerobic fermentation in a mediu m containing benzaldehyde. In a free cells survey skipping aerobic adaptati on before anaerobic fermentation caused all of benzaldehyde to be converted by 220 g (wet weight) of cells in 100 mt of the medium even at a higher co ncentration of 8 g/L benzaldehyde. The yield of L-PAC based on the moles of converted benzaldehyde increased as the amount of benzaldehyde dose was in creased. The encapsulation protected cells effectively from the toxicity of benzaldehyde. Even a small quantity, 1.1 g (dry weight), of encapsulated c ells in 100 mt of the medium containing 0.6% benzaldehyde converted more th an 95% of the benzaldehyde, and the corresponding yield of L-PAC was about 40%. The production of L-PAC by the encapsulated cells depended on the pH o f the medium. The conversion of benzaldehyde decreased slightly, but yield of R-PAC increased as the pH of the broth solution was fixed at a lower val ue. Biotransformation in a small side reactor of the batch system caused hi gher yield of L-PAC than that in the batch reactor containing the same quan tity of encapsulated cells during the first 4 hours of fermentation.