Hello everybody,
I've recently observed fast color change of Rhodomonas salina monoculture (RCC 1507), a switch from brown-red to light green (over a night). I'm growing my microalgae inside 2L glass Erlenmeyer, filled with autoclaved seawater (with K or K/2 media, 15-16°C, about 100 µmoles photon/m²/s) with filtered air inflow (bubbling), inside the batch.
The cell density is still increasing even the fast color change, can I link this phenomenon with nutrient limitation? Even if the nutrient are not totally depleted, and apparent growth occurs inside the batch? Or could it be associated to another stress (such as temperature fluctuation, pH shift or a virus maybe :O)? Has anyone ever observed this phenomenon with this specie?
Hi Jordan,
This is a "normal" feature of Rhodomonas salina. When it gets old/limited in nutrient (here especially in nitrogen), the red pigments (phycoerythrin) are degrading because they act as N reserves for limited cells to ensure growth. When I was working with this species, I considered the culture to be in a bad shape and not good to continue the experiment/culture when this light green color appeared. This change in pigment composition indicates N-starvation + beginning of carbohydrate accumulation followed by lipid accumulation. Your use of the culture after this change of color will depend on the purpose of your Rhodomonas. Indeed, for example this could be useful to increase lipid content especially in EPA and DHA but not suitable for accumulation of proteins content. I recommend the good paper by Latsos et al. 2020 in Frontiers that should answer most of your questions (doi: 10.3389/fmars.2020.563333)
Hi Marine,
Thank you for your answer.
It would be great for me if this colored change will be followed by PUFA accumulation, I used Rhodomonas salina to feed my copepods (I used a mix of different phytoplankton species btw). Rich PUFAs food source is generally associated to better egg production, nauplii somatic development and global zooplankton health. About the protein (very important for growth as well), it'll be provided by the other microalgae in my mix, don't worry about it ;-)
Thanks again Marine!
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