Differences in hydrogenase and APS-reductase activity between Desulfovibrio desulfuricans strains growing on sulphate or nitrate

The study compares growth rates and hydrogenase and APS-reductase activity in crude cell extracts obtained from eight wild strains of dissimilatory sulphate-reducing bacteria of the Desulfovibrio desulfuricans species, growing on sulphate or nitrate as sole energy source. The obtained results indicated that the investigated bacterial strains could utilize nitrate as an alternative terminal electron acceptor. Nitrate respiration abilities differed among the investigated bacterial populations. Some nitrate-utilizing cultures grew more rapidly than sulphate-utilizing ones, whereas other strains gave identical or inconsiderably lower cell density. This was true also when hydrogenase activity was analyzed. This enzyme-specific activity was generally almost directly proportional to the specific growth rate determined for strains cultured on sulphate or nitrate, respectively. The specific activity of APS-reductase indicated a large (10-20-fold) decrease in crude cell extracts obtained from bacteria growing in the presence of nitrate as compared to sulphate-utilizing ones.