I am cultivating Spirulina outdoors using the same culture for a few months now, and from one month ago I am noticing the apearance of some different cells. Before, my culture was composed by these longer, less coiled and more blue cells, and now I have a big amount of the smaller, more coiled and browner cells. I have also noted that when I centrifuge my culture the cells get distributed by a fraction in the bottom of the tube and another one "floating". When I observed microscopically I can see that the normal cells (longer and more blue) stay in the bottom of the tube and the smaller/browner ones float.
The percentage of the new cells is incresing more throughout the time and it is causing me trouble, because since they are smaller I can not efficiently harvest them with the filtration method I once was.
Does any one knows why this happen and if the small/brown cells can be converted back to its normal shape?
Hi,
It appears that your culture is either loosing chlorophyll, making the cells browner, and/or the culture is contaminated by another strain of spirulina. You can overcome these problems simply by enriching your culture with more nutrients, especially magnesium and calcium, and by streak plate to isolate the strain you originally had.
Good luck!
Yuvraj
The culture seems a bit "stressed", usually with such a small and fragmented Spirulina there is not much that you can do, but you can try to isolate again some long and healty Spirulina and start the culture again (check the light irradiance also)
In my opinion it is the long pale filaments that are the anomaly : unusually long filaments (>10 spires) are usually caused by a lack of iron, pale color comes with a lack of chlorophyll (an indication of stress), and healthy spirulina usually tend to float whereas stressed spirulina tends to sink.
You may also have 2 different strains in your medium. Try to spike the medium with iron and apply a very very gentle agitation, to see if you go back to a single phenotype (otherwise you have 2 strains)
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