Crocosphaera watsonii

Classification

Bacteria; Cyanobacteria; Oscillatoriophycideae; Chroococcales; Aphanothecaceae; Crocosphaera

Species

Crocosphaera watsonii

https://genome.jgi.doe.gov/portal/crowa/crowa.jpg

Description and Significance

Describe the appearance, habitat, etc. of the organism, and why you think it is important.

Crocosphaera watsonii is a diazotrophic marine cyanobacteria. They are unicellular nitrogen fixers that help turn nitrogen in the atmosphere into ammonia, restoring the circulation of nitrogen in the oceans. They are found in warm water conditions where the water temperature is above 24 degrees Celcius. These bacteria mostly reside in places that have low plant nutrients and a high abundance of dissolved oxygen. In regions of the oceans where there are low levels of nitrogen available, primary photosynthesis and production is limited. C. watsonii are very abundant in these regions and contribute a large amount of the nitrogen in these areas.

They are about 2.5-6 µm in diameter.

Genome Structure

Crocosphaera watsonii has six genomes with an average length of 5.885 Mbp. C. watsonii has many different strains that each contain a phenotypic difference. However, the majority of the DNA sequences from the strains are found to be nearly identical to one another. Through culturing and sequence conservation, studies have found that the strains have been able to maintain genetic diversity through divergence and rearrangement.

One strain of C. watsonii, WH8501, showed that the mobile genetic elements, like transposase genes, have provided ways for the bacteria to mutate through genetic insertions and deletions, and through rearrangement.

These mobile genetic materials are what separates C. Watsonii from other marine cyanobacteria such as Prochlorococcus which lacks transposase genes and normally has a higher diversity sequence than C. Watsonii.

The strains cultivated from C. Watsonii can be divided into two main phenotypic categories: those that are bigger than 4.0um in diameter and those that produce excess amounts of ESP, or exopolysaccharide that are attached to a slime layer on the microorganism and help protect against external factors. Bacteria bigger 4.0um usually do not show large amounts of ESP compared to smaller microbes.

Cell Structure, Metabolism and Life Cycle

C. Watsonii contains multiple thylakoid membranes located near the cytoplasmic membrane that is arranged in a lot of twisting clusters. It has a semipermeable cell membrane and starch granules that form barriers to oxygen gas.

Crocosphaera watsonii has a 35-hour doubling time. In the warm parts of the Atlantic and Pacific oceans, Crocosphaera watsonii has been found to have cell densities of above 1000 cells per milliliter.

Ecology and Pathogenesis

Habitat; symbiosis; biogeochemical significance; contributions to environment.

If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Crocosphaera watsonii can be isolated into two different phenotypes that can each have their own environmental impacts and niches.

References

Home - Crocosphaera Watsonii WH8501. (n.d.). Retrieved November 25, 2022, from https://genome.jgi.doe.gov/portal/crowa/crowa.home.html

Inomura, K. I., Deutsch, C., & Wilson, S. T. (2019, December 11). Quantifying oxygen management and temperature and light dependencies of ... Retrieved November 26, 2022, from https://journals.asm.org/doi/abs/10.1128/msphere.00531-19

Author

Page authored by Ashleigh Wright, student of Prof. Bradley Tolar at UNC Wilmington.