Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School



The four most abundant elements needed to support plant growth are carbon, hydrogen, oxygen, and nitrogen. Of these carbon, hydrogen, and oxygen are available to the plant in ample supply from the atmosphere and soil. Nitrogen, however, is available only in limited quantities in a form useable to the plant. The nitrogen is usually supplied in the form of nitrates or ammonium-nitrogen. The largest supply of nitrogen is in the atmosphere but it is in the elemental, uncombined form. Few plants, if any, are able to convert, directly or indirectly, this atmospheric nitrogen to organic matter. Plants which assimilate elemental nitrogen are said to “fix” nitrogen. The term nitrogen fixation will be used in this context. One group of “plants” which are capable of fixing nitrogen are certain species of bacteria. Most of the information concerning the mechanism of bacterial nitrogen fixation has been obtained in the last few decades. Workers in this area have turned to various areas in their study of the mechanism of nitrogen fixation. Some of these include: physiology, metabolic pathways, cell-free fixation, enzyme induction and repression, inhibitors, and the study and isolation of co-factors or combination of these studies. This study was, therefore, undertaken to extend the knowledge of the mechanism of nitrogen fixation by a nonsymbiotic fixing bacterium, Klebsiella pnumoniae. The effect of acetylene gas (which has a structure closely analogous to nitrogen gas) on the nitrogen fixation pathway of K. pneumonia was the subject of this study.

Library of Congress Subject Headings

Nitrogen -- Fixation
Klebsiella pneumoniae




South Dakota State University