AUTHOR=Löffler Michaela , Kümmel Steffen , Vogt Carsten , Richnow Hans-Hermann 

TITLE=H2 Kinetic Isotope Fractionation Superimposed by Equilibrium Isotope Fractionation During Hydrogenase Activity of D. vulgaris Strain Miyazaki

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01545

DOI=10.3389/fmicb.2019.01545

ISSN=1664-302X

ABSTRACT=<p>We determined <sup>2</sup>H stable isotope fractionation at natural abundances associated with hydrogenase activity by whole cells of <italic>Desulfovibrio vulgaris</italic> strain Miyazaki F expressing a NiFe(Se) hydrogenase. Inhibition of sulfate reduction by molybdate inhibited the overall oxidation of hydrogen but still facilitated an equilibrium isotope exchange reaction with water. The theoretical equilibrium isotope exchange δ<sup>2</sup>H-values of the chemical exchange reaction were identical to the hydrogenase reaction, as confirmed using three isotopically different waters with δ<sup>2</sup>H-values of – 62, +461, and + 1533‰. Expected kinetic isotope fractionation of hydrogen oxidation by non-inhibited cells was also superimposed by an equilibrium isotope exchange. The isotope effects were solely catalyzed biotically as hydrogen isotope signatures did not change in control experiments without cells of <italic>D. vulgaris</italic> Miyazaki.</p>