Microbes Team Up to Produce Vital Nutrient
In a recent study, researchers discovered a fascinating collaboration between microbes in the ocean that results in the production of an essential nutrient. The team, led by Tschitschko, identified a strain of bacteria called Gamma A that contained a nitrogenase gene. This gene is responsible for converting nitrogen in the atmosphere into a form that can be used by other organisms.
What made this discovery particularly intriguing was the fact that the nitrogenase gene in the Gamma A bacterium was not native to its genome. Instead, it appeared to have been acquired from a land-based rhizobia bacterium. Through genetic analysis, the researchers were able to trace the origin of the gene back to a marine diatom called Haslea. Within the Haslea diatoms, two bacterial species, Tectiglobus diatomicola and Tectiglobus profundi, were found.
The relationship between the Haslea diatoms and the Tectiglobus bacteria mirrors the symbiotic interactions seen between rhizobia bacteria and legumes on land. The bacteria provide nitrogen to the diatoms in exchange for energy produced through photosynthesis. This unique partnership allows the diatoms to thrive in the nutrient-poor ocean environment.
Further investigation into the evolutionary history of the rhizobia and Tectiglobus bacteria revealed that both groups acquired the nitrogenase gene through horizontal gene transfer from other bacteria. The researchers hypothesized that the Tectiglobus bacteria evolved their symbiotic relationship with the diatoms independently and earlier than their onshore counterparts.
The significance of this symbiotic relationship cannot be overstated. Tectiglobus bacteria are estimated to play a vital role in nitrogen fixation in the world’s oceans, rivaling the nitrogen-fixing capabilities of cyanobacteria like Trichodesmium. This process is essential for sustaining marine food webs and ecosystems.
The association between the Haslea diatoms and Tectiglobus bacteria challenges our understanding of how ecosystems function, particularly in nutrient-poor environments like the open ocean. The mutually beneficial arrangement between the two organisms highlights the remarkable adaptations that microbes undergo to survive and thrive in challenging conditions.
Interestingly, the Tectiglobus bacteria exhibit characteristics that suggest they may be on a path to becoming organelles within the diatom cells, similar to mitochondria and chloroplasts in plant cells. This transition would signify a deepening of the symbiotic relationship between the bacteria and their diatom hosts, potentially leading to further genome reduction and integration.
As scientists continue to unravel the complexities of microbial interactions in the environment, the discovery of the symbiosis between Haslea diatoms and Tectiglobus bacteria provides valuable insights into the diversity of relationships that drive nutrient cycling and ecosystem function. This study underscores the interconnected nature of life on Earth and the remarkable adaptability of microbes in shaping the world around us.
