Hello everyone,

My spirulina filaments get very long with time (some have more than 20 turns at day 9), and at >0.5 g/L the filaments get tangled very quickly after stirring has been stopped.

As a result, after 1 hour of settling I have a "wool ball" of flocculated biomass at the bottom of the flask... Which I'd like to avoid.

I've read that A.platensis flocculation and settling could be caused by N or P starvation, which lead to carbohydrate accumulation. It seems likely as entanglement appears lately, but I do not want to rule out other possibilities (contamination?)

But I did not see anything about very long filaments and entanglement, do you have any info on this ?

How to avoid / reverse this phenotype ?

I am running tests in Erlenmeyers using a modified Zarrouk medium (8 g/L bicar, KNO3 instead of NaNO3, monoammonium phosphate instead of potassium phosphate are the main changes), under artificial light with bubbled air+CO2. The strain is an unknown Paracas strain (long stretched filaments).