Can you elaborate the problem?

What algae are you trying to cultivate? What medium are you using? Could be good to take out a sample and look at it under the microscope to confirm what you have in the flask really is what you want. I would be suspicious if green precipitations formed.

Thanks for replay (Dola Bhattacharjee ·and Anna Zakrisson ), i was isolated marine microalgae (green and diatoms) more than 15 numbers of different species. i am using conways medium for microalgae culturing. but nowadays my culture was precipitated like below attachment photo. i cant find whats contamination this how to avoid this................among 15 only 2 strains changing like this......... can u help me................

Above attachments is fine culture, check this below attachment this is the problematic culture

Dunaliella? Synechococcus? Maybe.

Please check for contamination in the culture. Also if your strains are mat-forming, then this may happen. Is the light source is fitted at the bottom of the culture rack?

After 5 to 7 Days Culture is becoming Normal Because due to depletion of the Nutrients from the medium, so try to culture at different proportions of nutrients while changing the light illumination ! Also reduce the aeration don't aerate vigorously in the culture.

Well, if nutrients are depleted and they become normal, the ones that disapoear need to have radically different nutrient needs compared with the rest. Therefore, i am wondering if you are left with diazotrophs when they are normal? Please, use the microscope.

i thought its may depend on the medium preparation.................normally culture medium was prepared double distilled water.but this time RO water.............Normally cyanobacteria available in the fresh water......because of salinty precipitation automatically decreased or any other reason ?????????

Hi Kumar,

Some precaution steps for troubleshoot. The sterilization of multiwell plates. Use filtered ambient seawater as the first media-based when establishing new culture, follow by nutrient enrichment when the cell started to divide/grow asexually. Try to filter using 0.2 micron membrane to eliminate contaminants as much as possible. Use micropipette when perform single cell isolation under microscope. Transfer the targeted cell few times through the filtered ambient seawater to make sure only isolate one of that cell, normally happens to isolate also other algae, or ciliates.

And lastly, filter your culture medium before you autoclave it, that's what we normally do.

Cheers, HongChang