Preparation of Optically Active γ- and δ-Lactones by Microbiological Reduction of the Corresponding Keto Acids

Abstract

It was found, by means of simple screening methods, that several yeasts ( Saccharomyces and Candida ), molds ( Cladosporium ), and bacteria ( Sarcina ) are able to reduce keto acids to hydroxy acids, which are easily converted into lactones. Chemical analysis showed that some of the microorganisms ( Saccharomyces and Candida ) produce dextrorotatory lactones and others ( Cladosporium and Sarcina ) produce levorotatory lactones. High yields of dextrorotatory (both γ- and δ-lactones) were obtained by using Saccharomyces cerevisiae . The physical properties of the carefully distilled lactones obtained indicated high purity and high optical purity.