Kayoko:

There are several factors which may result in partial or perhaps complete loss of chlorophyll in cultures of B. braunii. Kindly see this link:

Best

Syed

Thank you Syed! The reference is helpful. Can I ask one more question?

Is it possible to restore chlorophyll to the cells?

Best regards,

Kayoko

Dear Kayoko,

B.braunii is difficult to grow without CO2. Even with CO2, the chlorophyll generally disappear after long cultivation (several month), but often, carotenoid are produced instead. It's depending on the strain or the race. But if you cannot see well visible cells in the matrix, it might mean your culture is dead. Observation of supernatant and pellet separately might also help to check if B.brauni is mainly as colonies or single cells in your culture.

Best regards,

Alexis

Better you do the subculture immediately. If possible try to bubble some C02.

Dear Alexis,

Thank you for the information! Your answer is really helpful. I still have small amount of green cells left so I will start culturing B.braunii under 5% CO2 immediately. It seems that about 50% of the white cells are single cells. How do you store/preserve the algae? I found some papers using a program freezer but we don't have one.

Dear Ramganesh,

Thanks! I will subculture asap and check CO2 bubbling system.