Bayer School of Natural and Environmental Sciences
John F. Stolz
Geobacter, nar, Nitrate reductase, Nitrogen metabolism, Thermus
Nitrogen metabolism was investigated in three species of iron respiring bacteria Geobacter metallireducens, Geobacter sulfurreducens, and Sulfurospirillum barnesii. G. metallireducens and G. sulfurreducens were shown to grow in medium containing N2, NO3-, or NH4 but nitrite inhibited growth. BLAST analysis of the draft genomic sequence of G. metallireducens revealed only Nar, Nrf, and Nif homologues but no assimilatory genes (i.e., Nas). Two nar operons were identified, narCGHJIK1K2, and narCGHI. A putative CAP/CRP recognition binding site was found upstream and two molybdenum biosynthetic genes were found downstream of the large operon. Both operons contain a novel cytochrome c (NarC) that has only been described in Thermus thermophilus strain HB8. An attempt was made to purify the periplasmic nitrate reductase (Nap) from S. barnesii without success. However, a method using lysozyme to solubilize Nap and a rapid activity assay for nitrate reductase using 96 well plates were developed.
Hsieh, C. (2003). Nitrogen metabolism in iron-respiring bacteria (Master's thesis, Duquesne University). Retrieved from https://dsc.duq.edu/etd/667