From Tjibbe-Chris Kuipers, summary of responses to a post to bionet.chlamydomonas March 1996
Hello, Some time ago I asked the following question:
Light intensity is used to regulate the dilution-speed. The problem is that the algae are sticking to the glass, so the intensity measured is not any longer related to the concentration of algae.
Does anyone know how to prevent the algae from sticking to the glass-surface? The reactor is now running for two weeks, and the problem appeared when the liquid velocity was enlarged.
These were the answers I got:
You might try replacing the glass with plastic, which the flagella would be less apt to adhere to.
You might try using a low concentration of a protein such as BSA or casein in your culture medium. I also seem to remember learning that folks who work with Tetrahymena use low concentrations of a surfactant in the culture medium. Marty Gorovsky at the University of Rochester might help you on the last point.
We occassionally use BSA in our buffers for just the reason you mentioned, but we have never tried using it for culturing cells. I would expect that you would increase the potential for contamination *and that you would get foaming. If I were you I would try to get in touch with someone who cultures large quantities of another protozoan.
I am familiar with the problem of Chlamy cells sticking to the gals walls of fermentors, I grow them in continuous cultures for months. I solve the problem in the following way. I introduce in the fermentor a teflon covered long magnetic rod which is sterilized at the same time as the fermentor and rests on the sides of the fermentor bottom. When there are cells sticking on the walls, I use an external strong magnet to catch the internal one and move the external magnet up and down or sideways so as to scrap all the cells from the internal fermentor surface. This cleaning procedure is done once every one or two days for a few minutes. Hope you may use this idea and eventually improve on it. Wish you luck.
Of the previous answers I used only the magnetic rod, which works OK, but is not possible to clean the whole reactor with it, because there is a double wall to cool the suspension. A few days ago I added about 2% vol of polystyrene beads and they seem to be able to keep the walls fairly well cleaned.