FIG. 3.

Nitrate and chromium reduction by bacterial isolate GNCr-4 grown anaerobically in basal medium amended with various concentrations of nitrate and chromium(VI) and 20 mM lactate as a carbon source. (A) The inhibitory effect of Cr(VI) upon nitrate reduction, as illustrated by the amount of nitrate reduced as increasing amounts of nitrate were added at 0, 0.1, or 0.25 mM Cr(VI). (B) For the set of cultures that grew at the highest Cr(VI) concentration (0.25 mM), the correlation between the amounts of nitrate and chromate reduced is shown. The amounts of nitrate and Cr(VI) reduced were lowest in cultures with 2.5 mM nitrate added and highest when 40 mM nitrate was present.