NITROGEN METABOLISM AND IRON REDUCTION IN AQUASPIRILLUM MAGNETOTACTICUM (NITRATE, FIXATION, MAGNETIC BACTERIUM)

<p>Aquaspirillum magnetotacticum strain MS-1 grew microaerobically but not anaerobically with NO(,3)('-) or NH(,4)('+) as the sole nitrogen source. Cell yields varied directly with NO(,3)('-) concentration under microaerobic conditions. Products of NO(,3)('-) reduction by growing cells included NH(,4)('+), N(,2)O, NO, and N(,2) but not NO(,2)('-) or NH(,2)OH. The inclusion of NH(,4)('+) in growth medium prevented NO(,3)('-) reduction to NH(,4)('+) but not to N(,2)O or N(,2). Cells consumed O(,2) while denitrifying and this appears to be the first described species with an absolute requirement for O(,2) while denitrifying.</p><p>Cultures grown with NO(,3)('-), in contrast to NH(,4)('+), contained fewer cells without magnetosomes. Moreover, among the cells with these intracellular magnetic particles, a higher average number per cell and a higher average cell magnetic moment was obtained with NO(,3)('-). This effect of cell nitrogen source on culture magnetism was investigated further with growing cells and cell-free extracts. The results indicated that Fe('+3) reduction by cell-free extracts of A. magnetotacticum was independent of electron transport chain components and suggested that Fe('+3) and NO(,3)('-) reduction proceeded independently in the cell.</p><p>A. magnetotacticum strain MS-1 and several non-magnetic mutants derived from it, fixed N(,2) (reduced acetylene) microaerobically but not anaerobically even with NO(,3)('-). Cells of A. magnetotacticum reduced acetylene at rates comparable to those of Azospirillum lipoferum under similar conditions but at a much lower rate than that of Azotobacter vinelandii grown aerobically.</p>

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Dissertation

Year

1984

Author dc:creator

• BAZYLINSKI, DENNIS ALFRED

• Biology
• Microbiology

Repository record dc:identifier

https://scholars.unh.edu/dissertation/1421

OAI identifier oai:identifier

oai:scholars.unh.edu:dissertation-2420