Nickel-Dependent Chemolithotrophic Growth of Two Hydrogenomonas Strains

Abstract

Bartha , R. (University of Washington, Seattle), and E. J. Ordal . Nickel-dependent chemolithotrophic growth of two Hydrogenomonas strains. J. Bacteriol. 89: 1015–1019. 1965.—The trace element requirements for growth of facultative chemolithotrophic Hydrogenomonas strains H1 and H16 were investigated under both autotrophic and heterotrophic conditions. The organisms were grown in a mineral medium, rendered deficient in trace elements by extraction with 8-hydroxyquinoline and chloroform, and, in some cases, by coprecipitation with copper. The organic substrates, succinate and fumarate, used for heterotrophic growth were treated in a similar fashion. Acetate and butyrate were purified by redistillation. It was found that iron alone was required for heterotrophic growth (optimal concentration, 1.5 × 10 −6 m Fe +++ ), but cells grown chemolithotrophically on molecular hydrogen required the addition of nickel. The yield of protein was proportional to the nickel added, reaching a maximum at 3 × 10 −7 m Ni ++ . Manganese, cobalt, copper, and zinc, alone or in combination, failed to substitute for nickel in the experiments with Hydrogenomonas . Although nickel is required specifically for the chemolithotrophic growth of Hydrogenomonas , nickel deficiency did not affect: (i) the synthesis or activation of hydrogenase, (ii) the Knallgas reaction, (iii) the assimilation of CO 2 by resting cells, or the synthesis of the storage material poly-β-hydroxybutyric acid. It is suggested that nickel participates in some reaction involved in CO 2 fixation by growing cells.