Nitrogen is a vital nutrient for sustaining life on our planet. Despite the abundance of nitrogen gas (N2), most organisms cannot access it without the process of nitrogen fixation, which converts dinitrogen to ammonium—a crucial inorganic nitrogen source.
A recent study on this topic was featured in the esteemed journal Cell.
UCYN-A form a symbiotic relationship with a closely related group of marine algae, B. bigelowii, in nutrient-poor regions of the open ocean. Unlike other nitrogen-fixing bacteria, UCYN-A lack the ability to regulate dinitrogen use when other nitrogen sources are available, allowing them to fix nitrogen gas into ammonium even in nutrient-rich environments. In return, the host provides carbon fixed photosynthetically by its chloroplasts.
The study delves into the discovery of a size correlation between UCYN-A and their symbiotic partner cells, mirroring the size relationships between other organelles and their hosts. As organelles grow larger, so do their host cells, eventually dividing and replicating. Mathematical modeling revealed the metabolic trade-offs that regulate relative cell size through nutrient acquisition and exchange.
“Converting nitrogen gas into a usable form requires a significant amount of energy and electrons,” explained Keisuke Inomura, assistant professor of oceanography at URI’s Graduate School of Oceanography and one of the study’s lead authors. “If UCYN-A are evolving into nitrogen-fixing organelles and we find similar cells in addition to B. bigelowii, it could have a profound impact on our understanding of nitrogen fixation.”
2024-04-03 22:00:04
Source from phys.org