Conversion of Fumaric Acid Fermentation to L-Malic Acid Fermentation by the Association of Rhizopus and Yeast Part I

Conversion of Fumarate to L-Malate by Yeast

Abstract

When fumaric acid fermentation by the genus Rhizopus is associated with another microorganism which has a high fumarase activity, this fermentation will be converted to L-malic acid fermentation. As a fundamental experiment of this investigation, 23 strains of yeasts belonging to the genera, Candida, Debaryomyces, Hansenula, Pichia, Rhodotorula, Saccharomyces and Torulopsis, were tested for their fumarase activities. Several strains indicating the high activity were all film yeasts and Pichia membranaefaciens, str. 3130, was found to be the best strain.
When P. membranaefaciens was cultured in the media containing Na- or Ca-fumarate (4% as fumaric acid) in still culture for 5 days, malic acid yields in either medium were more than 80% of theoretical value. On the other hand, Ca-fumarate was much more favorable than Na-fumarate as a substrate in shake culture, and the yields of malic acid in the Ca-fumarate-containing media were as high as 85% and nearly 100% after 2 and 5 days, respectively.
These results strongly suggest the possibility that the fumaric acid fermentation may be continuously converted to L-malic acid fermentation when P. membranaefaciens is cultured together with the genus Rhizopus.