New marine phytoplankton species have symbiotic organisms that produce “fertilizer”

Epithemia pelagica, one of the new diatom species. Credit: C. Schvarcz

The discovery of two new rare species of diatoms (phytoplankton) in Hawaii’s waters was announced by a team of researchers and collaborators at the Center for Microbial Oceanography, Faculty of Oceanography, University of Hawaii at Manoa. At the University of California Santa Cruz and the University of California San Marcos. Organisms have also been found to fix nitrogen. This is an important process that transforms gaseous nitrogen into a form that supports productivity in the nutrient-poor open ocean in which they live.The survey results have been published at Nature Communications..

Diatoms with intricately patterned cell walls made of glassy silica are some of the most well-known and charismatic ones. Phytoplankton.. They work best in nutritious conditions.Open with less nutrients Ocean In the waters around Hawaii, diatoms struggle to get enough nitrogen to grow.

Several diatoms have been established to solve this problem Symbiotic relationship With nitrogen fixation Cyanobacteria.. These special endosymbiotic cyanobacteria can take dissolved nitrogen gas (abundant in seawater but inaccessible to diatoms) and convert it to ammonia. Ammonia is a form of nitrogen that diatoms can easily use, but otherwise it is very sparse in the open ocean. By containing cyanobacteria in the glass house, diatoms have their own nitrogen generator. They become a self-fertilization system.

Reveal almost invisible

“Oceanographers know about these diatom-Cyanobacteria have been symbiotic in the waters around Hawaii for many years, but the species we have discovered are completely different, “said Christopher Schwartz, C-MORE researcher and lead author of the study.

New marine phytoplankton species have symbiotic organisms that produce

A new species was isolated from a water sample taken at Station Aloha. Credit: P. Lethaby / UH

A better-known example of these types of symbiosis is that the diatomaceous host is a large “centrocyte” with radial symbiosis, and the endosymbiotic cyanobacteria that inhabit them emit a bright yellow-orange color. Due to the formation of chains, it is very easy to find under a microscope. It fluoresces when illuminated by blue light.

The new diatom species isolated by Schvarcz belong to smaller, symmetrical, elongated and different strains. These symbiotic organisms are also smaller, unicellular, and chlorophyll-free, so they do not glow under fluorescent light and are almost invisible inside diatoms. This probably explains why they haven’t been detected for so long. Schvarcz adds a sample of seawater to a nitrogen-poor growth medium in the laboratory and carefully examines the culture under a microscope for weeks to months to see what kind of phytoplankton grows. By doing so, I discovered a new species.

“The results were amazing,” said Grieg Steward, a professor of UH Manoa who worked with Schwartz on the project. “The new diatoms are related to the species found in freshwater. I never thought their cousins ​​were thriving in the open ocean. How much Chris’s work can be learned with a little patience and careful observation. It’s an important thing to remind you of what you can do.

Find unusual patterns

Another surprise came when the team measured the daily pattern of nitrogen fixation in the culture. Species previously studied tend to concentrate nitrogen fixation activity either during the day or at night, but not both.

“With these new species, we have discovered a rare hybrid pattern,” says Sam Wilson, a C-MORE researcher who led the effort to measure nitrogen fixation in cultures using custom-made equipment. I did. “These cells fix nitrogen It starts in the dark at midnight and lasts in the morning, afternoon, and evening. Then they take a 6 hour break around the sunset. I’m still not sure why they do this, but finding this strange pattern is exciting. That means you’re trying to learn something new about the old process. ”

Evidence of diatoms communicating with each other using autofluorescence was found

For more information:
Christopher R. Schvarcz et al, Overlooked and Widespread Sea Pennant Diatom-Diazotroph Symbiosis, Nature Communications (2022). DOI: 10.1038 / s41467-022-28065-6

Quote: New marine phytoplankton species include “fertilizer” (2022) obtained on February 15, 2022 from https: // There is a symbiont that produces (February 15, 2014)

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New marine phytoplankton species have symbiotic organisms that produce “fertilizer”

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