Gluconic Acid Fermentation by Pullularia pullulans

Abstract

During the study on the sugar metabolism of molds, several strains of Pullularia pullulans were found to produce large amounts of gluconic acid from glucose. Thirty seven strains of P. pullulans were then tested for their acid-producing abilities. Seven strains did not produce any amount of gluconic acid. However, all of the other strains were shown to be capable of producing this acid. The superior strains produced yiclds of gluconic acid as high as about 90%, based on glucose available, in shaking cultures at 30°C after 2 days. The yields were increased up to approximately 100% during later stages. In addition to high yields, gluconic acid was produced exclusively by these strains. Glutamic acid and inorganic ammonium salts, such as (NH4)2SO4, NH4Cl and (NH4)2HPO4, were favorable nitrogen sources for acid production. In the case of (NH4)2SO4, the optimum concentration was 0.05%. The addition of CaCO3 was essential for gluconic acid production by P. pullulans and a 3% concentration of CaC03 appeared to b...