Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

First Advisor

Robert M. Pengra


There are many nutrients in a farming operation which can limit production. Nitrogen deficiencies are found more often than any other. Crop yield increases needed to meet world population growth result in a greater demand for nitrogen. The commercial chemical manufacturer of fertilizer nitrogen by the Haber-Basch method is very energy intensive. Biological nitrogen fixation as an alternative source of nitrogen is now being extensively studied. The legume-rhizobium symbiosis has been well documented. This symbiosis has occurred for centuries yet the knowledge of its process and how it helps to decrease fertilizer nitrogen requirements was welcomed by the agricultural community. Another valuable contribution is that of the associative nitrogen fixing bacteria and the plant root. A number of studies have found rhizophere nitrogen fixation contributes significant amounts of nitrogen toward plant growth. Other studies have determined that the amount is insignificant. There have been many reports of exudation of organic compounds by the root and characterization of these exudates. Exuded carbohydrates may be used by associative nitrogen fixers. Valuable knowledge must be collected to determine which exuded carbon and energy sources can be used by nitrogen fixing bacteria in the rhizosphere.

Library of Congress Subject Headings

Nitrogen -- Fixation
Anaerobic bacteria
Klebsiella pneumoniae



Number of Pages



South Dakota State University


No Copyright - United State