Spirulina powder under a microscope
Spirulina powder is often sold as as a "nutrional supplemnt" or "health food" with claims such as supporting brain health, cardiovascular health, healthy and youthful looking skin , boosting the immnue system as well as antioxidant and anti-inflammatory properties.
Spirulina is actually a kind of algae, also known as cyanobacteria. Sprulina powder is actually made from the genus Arthrospira, both Arthrospira platensis and Arthrospira maxima. This genus was formerly classified as Spirulina and a lot of confusion remains about the classification of these species.
Advertisements for spirulina powder and tablets usually just show the product itself or occsionally live fresh spirals of Arthrospira or even related species in the genus Spirulina. You might expect that the powder doesn't really look like that, and you'd be right. Here is what it looks like @ 250x under normal substage lighting:
This view isn't exactly inspiring and it certainly doesn't look very appetizing! Perhaps a view under superstage lighting would look better:
While this view is certainly more appealing, there still isn't a lot of visible structure. It is common practice in microscopy to place a small amount of a powder such as this on a slide then add a few drops of water and a coverslip. This is what is known as a wet mount. This spreads out the powder making individual grains more visible and also results in better light transmission, preserving the resolving power of the microscope. Since Spriulina powder is often mixed into a drink and would be mixed with saliva if taken as a dry powder, this represents a truer picture of what you are consuming anyway:
Note that this image is cropped instead of just being resized and is at 400X. Clicking on the image will show the full version of this image as it will with the above images.
Here we can see a lot more visible structure and, though no staining technique was used, in many cases the nucleus of an individual cell is visible. Though no complete spirals can be seen, the curved shape of these strings makes it clear that they were part of a larger spirals which became broken after they were dried, making them much more fragile. The absorbtion of water also caused the strings to swell, thus making them larger than they were as part of a dry powder, and restoring them to an appearance more similar to what they looked like when still alive.
This brings up another question:
Is the powder dead, or is it just dormant, waiting for the addition of light, water and nutrients to begin growing again and forming complete spirals? When water was added and it was exposed to light for a week or so, the result was less than promissing. An occasional small string could be found, but no complete or partial spirals were found, though many bacteria and other critters were found, apparently feeding on the algae. So, it would appear that the algae cells contained within the powder are, indeed dead.