The Aeration-Dependent Effect of Vitamin B₁₂ on DNA Biosynthesis in Methylobacterium dichloromethanicum

Author： Danilova I. V. Doronina N. V. Trotsenko Yu. A. Netrusov A. I. Ryzhkova (Iordan) E. P.

ISSN： 0026-2617

Source： Microbiology, Vol.73, Iss.2, 2004-03, pp. : 134-138

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Abstract

The effect of vitamin B₁₂ (cobalamin) on DNA biosynthesis in Methylobacterium dichloromethanicum was studied. When cultivated in media with methanol or dichloromethane, the bacterium produced approximately 10 μg corrinoids per gram dry biomass, compared to about 7 μg/g when cultivated on ethanol or succinate. Exogenous adenosylcobalamin (AdoCbl) stimulated DNA biosynthesis in M. dichloromethanicum cells grown under poor aeration, the effect being mediated by AdoCbl-dependent ribonucleotide reductase. In vitro studies showed that M. dichloromethanicum also has AdoCbl-independent ribonucleotide reductase. Under good aeration, exogenous AdoCbl had no effect on DNA biosynthesis, while hydroxyurea suppressed it. These data suggest that AdoCbl-independent ribonucleotide reductase, which is likely to be activated by oxygen, plays an important part in DNA biosynthesis when M. dichloromethanicum is cultured with good aeration, whereas AdoCbl-dependent ribonucleotide reductase is active under conditions of poor aeration.