Approaches to Improving the Potential of Azotobacter Vinelandii As a Biofertilizer

The industrial Haber-Bosch process responsible for a large portion of ammonia production comes at the expense of fossil fuels. Azotobacter vinelandii is a widely studied model diazotrophic (nitrogen fixing) bacterium, and also an obligate aerobe, differentiating it from many other diazotrophs that require environments low in oxygen for the function of the nitrogenase enzyme. This property makes A. vinelandii a key target strain for a range of nitrogen biosynthetic processes, including co-culture in mass algal production facilities. Our laboratory has been developing approaches and tools to screen for elevated nitrogen production through rational pathway manipulation and random insertional mutagenesis approaches. Several approaches have resulted in elevated production of specific nitrogen compounds that are sufficient to support the growth of either algae or traditional agricultural crops. Current efforts to expand this approach are studying the potential of developing new symbiotic relationships between A. vinelandii and target crops, while further efforts to utilize either plant exudates, residuals or cellulosic by-products would improve the application of biofertilizers further. Studies of transcriptional changes in a high nitrogen production strain are providing a glimpse of how the cell self regulates various processes that enable the flow of significant metabolic flux towards nitrogen fixation, and new tools developed recently should result in further strain enhancements that will improve the application for important nitrogen containing bioproducts. Finally, studies demonstrating the potential to apply new biofertilizer strains to both algae and traditional crops will be presented.