New research led by MIT scientists reveals that the Prochlorococcus microbe, a crucial phytoplankton for carbon capture, likely colonized the open ocean by using chitin particles from ancient exoskeletons as rafts. This innovative mechanism allowed the species, which once thrived in nutrient-rich coastal areas, to venture into deeper ocean waters. Prochlorococcus, now the most abundant phytoplankton, plays a significant role in absorbing carbon dioxide, comparable to terrestrial forests. The study posits that by exploiting chitin rafts, these microorganisms gained essential nutrients and the ability to adapt to the ocean’s environment. Genetic analyses indicate that certain strains of Prochlorococcus can degrade chitin, suggesting a historical adaptation to this resource. The researchers traced the evolution of this capability to the early Paleozoic era, coinciding with the rise of aquatic arthropods. This timing underscores how the availability of chitin provided opportunities for coastal microbes to evolve into free-floating ocean dwellers. The findings highlight the interconnected evolution of ecosystems, emphasizing how both arthropods and picocyanobacteria, like Prochlorococcus, expanded their habitats into the open ocean, shaping marine biodiversity. The full study was published in the Proceedings of the National Academy of Sciences on May 9, 2023.
