Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School



In recent years the biochemical aspects of molybdenum have come under increasing investigation. One phase of the investigation has centered on the function of Mo in nitrogenase enzymes. One way to study the biochemical function of an element with another which may mimic its function. A vanadium containing mitrogenase from Aztobacter vinalaudii has been prepared which displays properties indicative of replacement of the Moo by V. Attempts to prepare an active tungsteu analog have been unsuccessful as W exhibits an inhibitory effect. It has been suggested that rhenium analogs of Mo-nitrogenase rather than V or W, should be more useful in elucidating the role played by molybdenum. This work dealt specifically with the substitution of V and Re for the Mo requirement of Azotobacter vinelandii. Growth rate measurements were performed on cultures grown in the absence of any added Mo (Nil-medium), the presence of added V or Re (V-medium or Re-medium) and the presence of Mo (Whole-medium). The levels of Mo contamination contributed by each media component and Mo concentration in the complete media of each type were determined by atomic absorption analysis. The nitrogenase activities of whole cell cultures was measured by means of the acetylene/ethylene reduction method. The reported ability of Mo (but significantly not V) to overcome the competitive inhibition of nitrogenase by W led to an investigation into the behavior of Re in W inhibited cultures.

Library of Congress Subject Headings


Nitrogen -- Fixation

Bacteria, Denitrifying



Number of Pages



South Dakota State University