Parameters Affecting Methanol Utilization by Yeasts

Abstract

Screening of 28 yeast cultures, representing 22 species of various yeasts, with respect to their capabilities to assimilate methanol, has shown that this property was mostly found in certain species of the two genera Hansenula and Candida. When methanol was used as a sole carbon source for a methanol-adapted strain of Hansenula polymorpha, a linear yield response could be obtained with increasing alcohol up to 2% concentration. The amount of inoculum proved to be the decisive factor in determining a priori the ability of the organism to grow at 6% methanol as final concentration. The optimum pH values for growth ranged between 4.5 – 5.5 with no growth at pH 6.5 or higher. A marked growth stimulation was obtained when the medium was supplied with phosphate up to 0.08 M as final concentration. Within the nitrogen sources tested, corn steep liquor concentrate gave the highest yield of cells. The significance of the obtained results are discussed with reference to feasibilities of application.

Unter 22 verschiedenen Hefearten waren Hansenula und Candida in der Lage, Methanol als alleinige C-Quelle zu verwerten. Bis zu einem Alkoholgehalt von 2% war bei H. polymorpha eine lineare Beziehung zwischen Alkoholzusatz und Wachstum zu verzeichnen. Bei höheren Methanolzusätzen (6%) war die Größe des Inokulums entscheidend für eine a priori-Einschätzung möglichen Wachstums. Für ein optimales Wachstum waren weiterhin erforderlich: ein pH-Bereich von 4,5 – 5.5 (nicht ≥ pH 6,5), ein Zusatz von P (0,08 M) sowie Maisquellwasser-Konzentrat.