Regeneration of NAD(H) by alcohol dehydrogenase in gel-entrapped yeast cells

Anaerobically grown cells of Saccharomyces cerevisiae entrapped in polyacrylamide gel have been shown to provide a stable source of alcohol dehydrogenase [(ADH) alcohol:NAD⁺ oxidoreductase, EC 1.1.1.1] for effective regeneration of NAD(H). This system was able to provide the coenzyme required for the operation of other dehydrogenases, such as lactate dehydrogenase [(LDH) l-lactate: NAD⁺ oxidoreductase, EC 1.1.1.27] and malate dehydrogenase [(MDH) l-malate:NAD⁺ oxidoreductase, EC 1.1.1.37]. Yeast cells coimmobilized with a dehydrogenase are capable of the reversible regeneration of the reduced or oxidized coenzyme, depending on the additions made. A two-cell system can also be constituted using the same strain of yeast, adapted differently. Cells grown anaerobically and aerobically as sources of ADH and MDH, respectively, can operate efficiently on coimmobilization. The system can be used repeatedly without measurable loss of efficiency.