Azotobacter vinelandii stimulated the growth of Agrobacterium tumefaciens H2, H23, H24, H27, and ATCC 15955 on media containing insoluble iron sources. The Azotobacter vinelandii siderophores appeared to promote Agrobacterium tumefaciens growth by solubilizing mineral iron, and the ferrisiderophores so formed then acted as iron sources for Agrobacterium tumefaciens. Agrobactin, the Agrobacteriu...

Four laboratory strains and two isolates of Azotobacter vinelandii were found to contain plasmids. Twenty-five laboratory strains which could fix nitrogen did not have free, covalently closed circular plasmid DNA. The plasmids varied in size from 9 to 52 megadaltons, and each strain yielded only one plasmid. No discernible differences in ability to fix nitrogen were found between plasmid-bearin...

Methods employed in the study of the fluorescent culture filtrates of Azotobacter are described. The use of a fluorescence meter in the characterization of the fluorescent substances elaborated by Azotobacter agile, Azotobacter vinelandii, and Azotobacter macrocytogenes n. sp. is discussed. A. macrocytogenes, a fluorescent species, is included with the two previously reported fluorescent Azotob...

A new type of ferredoxin was isolated from Azotobacter vinelandii cells. The protein was able to replace the native chloroplast ferredoxin in the photoreduction of nicotinamide adenine dinucleotide phosphate (NADP) and functioned as a reductant for the Azotobacter nitrogenase.

An enrichment technique was developed whereby azotophage could readily be isolated after inoculation of soil sites with Azotobacter vinelandii.

Four types of utilization of nitrate nitrogen were observed with fourteen strains of the azotobacter. These were: (a) Those which utilize NO;-N with no or only a short lag; three strains of Azotobacter winelandii, a stock culture of A. chroococcum C-77, and seven strains of A. chrmoccum freshly isolated from soil were in this group; (b) A single strain, a stock culture of A. chroococcum C-44, w...