Gene fitness of Azotobacter vinelandii under diazotrophic growth

Carolann M Knutson, Meghan N. Pieper, Brett M. Barney

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Azotobacter vinelandii is a nitrogen-fixing free-living soil microbe that has been studied for decades in relation to biological nitrogen fixation (BNF). It is highly amenable to genetic manipulation, helping to unravel the intricate importance of different proteins involved in the process of BNF, including the biosynthesis of cofactors that are essential to assembling the complex metal cofactors that catalyze the difficult reaction of nitrogen fixation. Additionally, A. vinelandii accomplishes this feat while growing as an obligate aerobe, differentiating it from many of the nitrogen-fixing bacteria that are associated with plant roots. The ability to function in the presence of oxygen makes A. vinelandii suitable for application in various potential biotechnological schemes. In this study, we employed transposon sequencing (Tn-seq) to measure the fitness defects associated with disruptions of various genes under nitrogen-fixing dependent growth, versus growth with extraneously provided urea as a nitrogen source. The results allowed us to probe the importance of more than 3,800 genes, revealing that many genes previously believed to be important, can be successfully disrupted without impacting cellular fitness. IMPORTANCE These results provide insights into the functional redundancy in A. vinelandii, while also providing a direct measure of fitness for specific genes associated with the process of BNF. These results will serve as a valuable reference tool in future studies to uncover the mechanisms that govern this process.

Original languageEnglish (US)
Article numbere00404-21
JournalJournal of bacteriology
Issue number24
StatePublished - Dec 2021

Bibliographical note

Funding Information:
This work was supported by grants from the MnDRIVE transdisciplinary research initiative through the University of Minnesota based on funding from the state of Minnesota, the National Institute of Food and Agriculture (project no. MIN-12-070 and MIN-12-081) and award number 2020-67019-31148 through the United States Department of Agriculture. Carolann M. Knutson was further supported through funding from the National Science Foundation (CBET-1437758) and a BBE Graduate Fellowship from the Department of Bioproducts and Biosystems Engineering.

Publisher Copyright:
Copyright © 2021 American Society for Microbiology. All Rights Reserved.


  • Azotobacter vinelandii
  • Gene essentiality
  • Nitrogen fixation
  • Tn-seq


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