Mutants of methylotrophic yeast Hansenula polymorpha with defective formaldehyde reductase
1990
Sibirnyi, A.A. | Ksheminskaya, I.P. | Ubiivovk, V.M. | Gonchar, M.V. | Kapul'tsevich, Yu.G. | Bliznik, K.M.
Mutants of the methylotrophic yeast Hansenula polymorpha resistant to allyl alcohol when raised in glucose medium have been selected. They retained the ability to propagate in media containing ethanol, glycerol, or methanol. Mutant cells in the exponential growth phase were characterized by substantially diminished alcohol dehydrogenase activity and almost entirely lacked formaldehyde reductase activity. One of the alcohol dehydrogenase isozymes apparently exhibited formaldehyde reductase activity when raised in methanol medium. Mutant cells from the lag phase accumulated larger quantities of formaldehyde in methanol medium, indicating that formaldehyde reductase plays a role in regulating cell formaldehyde level. Formaldehyde accumulation in the CF of the mutants was accompanied by a drop in activity levels for alcohol oxidase, alcohol dehydrogenase, and formaldehyde dehydrogenase and by reduction of the ATP pool. Formaldehyde content subsequently dropped and enzyme activity levels and the ATP pool normalized. NADH content was somewhat lowered in the mutant cells. The mutants did not differ from the wild-type SUM in growth rate or biomass yield on methanol in either batch or continuous culturing. The role of formaldehyde reductase in methylotrophic growth is discussed.
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