FIG 3.

Current consumption occurs in a hydrogenase deletion mutant (Δhyd) across a range of −400 to −500 mV and is inhibited by BES. Representative current profiles for the M. barkeri mutant (Δhyd) (described in reference 28), including experiments with cells (washed culture) and the cell growth medium only (spent media) at both −400 mV (A) and −500 mV (B). Changing the hydrogen concentration to include an 80%/20% mix of hydrogen and carbon dioxide did not alter the current consumption, though the addition of BES at 18 h demonstrated inhibition in the reactors containing cells (C).