This thesis was written to study photoreactivation in different physiological conditions of the vegetative cell as well as the photoreactivation of the two morphological states of the Azotobacter cell: the vegetative cell and the cyst.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 160-179). Also available via the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [94]-103).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1955. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 40-42).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1952. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 112-119.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Vita. Includes [as parts II and III] : Calcium and polymetaphosphate synthesis in Azotobacter vinelandii O / [Raymond G. Esposito ; P.W. Wilson]. Reprinted from Biochimica et biophysica acta, vol. 22 (1956), p. 186-187 -- Trace metal requirements of Azotobacter / Raymond G. Esposito and Perry W. Wilson. Reprinted from Proceedings of the Society for Experimental Biology and Medicine, vol. 93 (1956), p. 564-567. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 70-74).

Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 73-78).

Nineteen laboratory strains of Azotobacter vinelandii and two organisms of the same species isolated from water samples were screened for the presence of plasmid deoxyribonucleic acid (DNA). Three laboratory strains and both organisms isolated from water samples contained one plasmid each. The migration distances of the plasmids in agarose gel electrophoresis were different molecular weights. The plasmids were cured by SDS or ethidium bromide treatment of the cultures.

The enzyme nitrogenase, which catalyzes nitrogen fixation in Azotobacter vinelandii, consists of two components, the Fe protein (NifH) and the MoFe protein (NifDK). NifK contains several highly conserved residues implicated in its functions throughout the protein. However, the carboxyl terminus of NifK is not implicated in any of the known functions of this protein. Therefore, the present study explored the role of carboxyl terminal region of NifK. The results of growth analysis showed that when the media was adjusted to be slightly acidic, the strain that expresses the mutated NifK yielded a lower growth compared to the wild type. These observations implied that the carboxyl terminus of the NifK contributes to the formation of a stable nitrogenase complex when A. vinelandii is grown in acidic environment. The proper interaction between NifH and NifK is essential for the nitrogenase conformation. To determine how the interaction is influenced by the characteristics of the amino acids available at position 112 of NifH, we introduced residue mutations to the codon encoding for Glu112. Growth analyses indicated that mutant strains are capable of propagation under nitrogen-deficit conditions although the growth rate is lower than that of wild type strain. Therefore the charge carried by the amino acid at position 112 of NifH plays a minor role in the interaction whereas; a more important factor is the length of the side chains. The research on hydrogenase expressed by bacteria shed light on the possibilities of utilizing this novel energy source. We endeavored to take advantage of the nature of A. vinelandii and construct an A. vinelandii mutant strain expressing Fe-hydrogenase. This ongoing research involves molecular manipulation of the enzyme-encoding gene hydA. The synthetic hydA was incorporated and expressed in A. vinelandii strain DJ54. At the same time, we screened several biomass materials for their capabilities in sustaining diazotrophic growth of A. vinelandii. The result indicated that the HydA protein can be expressed in A. vinelandii under certain conditions and a number of biomass substances can be supportive ingredients for putative biohydrogen media.