[Deuterium oxide as a stress factor to the methylotrophic bacterium Methylophilus sp]. / Oksid deiteriia kak stressovyi faktor u metilotrofnykh bakterii Methylophilus sp.

The adaptation of the methylotrophic bacterium Methylophilus sp. B-7741 to growth in highly deuterated media was studied. For the first time, we showed the cross adaptation of bacterial cells to deuterated media and oxidative and osmotic stresses. The activity at catalase in deuterated cells was higher than in the control cells. Deuterated cell-free culture liquids showed protective effects on the growth of Methylophilus sp. B-7741 in deuterated media, which was manifested as an increase in the deuterated biomass yield. These data and the data available in the literature suggest that the mechanisms of bacterial cell adaptation to heavy water and to oxidative and osmotic stresses are similar.

[Effect of deuteration on methanol dehydrogenase activity in Methylophilus sp. B-7741]. / Vliianie deiterirovaniia na aktivnost' metanoldegidrogenazy Methylophilus sp. B-7741.

We studied the effect of deuterium oxide present in the medium on the activity of methanol dehydrogenase (EC 1.1.99.8) from methylotrophic bacteria Methylophilus sp. B-7741. Methanol dehydrogenase activity in extracts of the biomass obtained in a highly deuterated medium (2H-enzyme) was 34-47% of enzyme activity in the control biomass, which depended on reaction conditions. The isotopic effects of substrate deuterium (methanol) for 1H-enzyme and 2H-enzyme were 1.37 +/- 0.05 and 1.38 +/- 0.01, respectively. We revealed for the first time the reverse isotopic effect of solvent deuterium in the reaction catalyzed by methanol dehydrogenase (0.80 +/- 0.02 and 0.60 +/- 0.01 for 1H-enzyme and 2H-enzyme, respectively).