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<p>The discovery of the nitroplast captured our interest - we had considered a project on nitrogen fixation before but failed to see a way in which we could innovate or propose new solutions to the problems previous teams faced. All diazotrophs (bacteria and archaea that fix atmospheric N<sub>2</sub>) use the <strong>enzyme nitrogenase</strong> to fix nitrogen, but the expression of this enzyme presents great difficulties: it is <strong>irreversibly damaged by reacting with oxygen</strong>, while at the same time catalyzing an energetically demanding reaction. Due to this, diazotrophs have evolved very complex mechanisms to couple nitrogen fixation with respiration and/or photosynthesis, which so far has been beyond reach in terms of reproduction by synthetic biologists. The <strong>nitroplast solves this problem, acting as a fully contained compartment within a eukaryote where nitrogen fixation takes place</strong>, utilizing several years of evolutionary optimization.</p>
<p><strong>Symbiotic relationships</strong> between diazotrophs and plants already exist in nature, specifically in crops - legumes have a relationship with rhizobia (bacteria living around the plant root), as do some grass species with other nitrogen-fixers. However, most <strong>other crops do not have anything of the sort</strong>. Besides transgenic nitrogenase expression, the other main avenue currently being explored in nitrogen fixation is the <strong>engineering of external symbiosis</strong> between diazotrophs and other plants. However, this poses a challenge in replicating fragile extracellular signaling pathways and physical conditions that are dependent on the plant species' roots, as well as potential containment issues.</p>
