N2-dependent growth and nitrogenase activity in the metal-metabolizing bacteria, Geobacter and Magnetospirillum species.

TitleN2-dependent growth and nitrogenase activity in the metal-metabolizing bacteria, Geobacter and Magnetospirillum species.
Publication TypeJournal Article
Year of Publication2000
AuthorsBazylinski DA, Dean AJ, Schüler D, Phillips EJ, Lovley DR
JournalEnviron Microbiol
Volume2
Issue3
Pagination266-73
Date Published2000 Jun
ISSN1462-2912
KeywordsAcetylene, DNA, Bacterial, Ethylenes, Genes, Bacterial, Iron, Nitrogen Fixation, Nitrogenase, Oxidation-Reduction, Oxidoreductases, Proteobacteria, Rhodospirillaceae
Abstract

Cells of Geobacter metallireducens, Magnetospirillum strain AMB-1, Magnetospirillum magnetotacticum and Magnetospirillum gryphiswaldense showed N2-dependent growth, the first anaerobically with Fe(III) as the electron acceptor, and the latter three species microaerobically in semi-solid oxygen gradient cultures. Cells of the Magnetospirillum species grown with N2 under microaerobic conditions were magnetotactic and therefore produced magnetosomes. Cells of Geobacter metallireducens reduced acetylene to ethylene (11.5+/-5.9 nmol C2H4 produced min(-1) mg(-1) cell protein) while growing with Fe(III) as the electron acceptor in anaerobic growth medium lacking a fixed nitrogen source. Cells of the Magnetospirillum species, grown in a semi-solid oxygen gradient medium, also reduced acetylene at comparable rates. Uncut chromosomal and fragments from endonuclease-digested chromosomal DNA from these species, as well as Geobacter sulphurreducens organisms, hybridized with a nifHDK probe from Rhodospirillum rubrum, indicating the presence of these nitrogenase structural genes in these organisms. The evidence presented here shows that members of the metal-metabolizing genera, Geobacter and Magnetospirillum, fix atmospheric dinitrogen.

Alternate JournalEnviron. Microbiol.
PubMed ID11200427