Engineering nitrogen-fixing microbial communities associated with maize and sorghum roots

May 23, 2024


Zoom Webinar


Dr. Jean-Michel Ané

Department of Bacteriology, Department of Plant & Agroecosystem Sciences

University of Wisconsin, USA


Nitrogen is an essential nutrient for plants, and its availability often limits yield and biomass production. In particular, cereal crops such as maize and sorghum require high nitrogen inputs. Synthetic nitrogen fertilizers, produced from natural gas through the Haber-Bosch process, can alleviate this limitation. However, their intensive use leads to significant economic and environmental issues (nitrogen leaching and production of greenhouse gases). A promising approach to reduce dependence on synthetic fertilizers is to engineer nitrogen-fixing bacteria associated with cereal crops to fix more nitrogen and release the nitrogen they fix in the form of ammonium, which plants can use. Unfortunately, despite their capacity for constitutive enhanced nitrogen fixation, these engineered strains suffer from a significant fitness defect that limits their practical application in agriculture. Here, we will describe two novel approaches to improve the fitness of these ammonium excreters. The first approach is to engineer nitrogen-fixing bacteria with biosensors that will trigger the nitrogenase activity and ammonium excretion only after perceiving signals such as arabinose or flavonoids produced by the host plants with which they are associated. The second approach involves using synthetic communities (SynComs) to better understand bacterial interactions in the rhizosphere. Specifically, our approach aims to identify potential helper bacteria to enhance engineered nitrogen-fixers’ nitrogen fixation and delivery ability and to identify potential competitors. Altogether, these approaches based on biological nitrogen fixation will be a sustainable alternative to synthetic fertilizers for food, feed, fiber, and biofuel production.

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