I was isolating a single organism of rhizosolenia, that was placed f/2 medium. Rather than growing, after three weeks the organism died. Can anyone explain this organism's life-cycle? Are there any other isolating and culturing methods I should try?
The success of your algal culture is dependent on various conditions: concentration and quality of the starter population; type of medium used; concentration of fertilizer, light and aeration. For liquid medium you need at least 10^4 cells. If you use aeration, your culture will peak in 3-5 days based on the concentration of your fertilizer, hence, need to be subcultured. Unaerated culture can lasts for weeks with occasional swirling of the medium. For algal population less than 10^4 cells, solidified medium (1.5%agar with either F/2 or TMRL) is recommended by streaking or spreading a drop of culture onto the agar allowing the units to isolate themselves by creeping away from the contaminants. before it is transferred to liquid medium for massproduction.
I hope this will be of help to you. Good luck.
i think it should not be a problem to culture rhizosolenia .... I believe you must be using serial dilution technique in your isolation procedure ..... what is more important is that maintaining the salinity of the media (f/2) in appropriate to the salinity of the water sample from which you are isolating the cells. secondly as you said after three week the cells collapse ... how often you do sub culturing ??? since they have a short life cycle so its always better you inoculate them in fresh media after every 8-10 days. Since the rhizosolenia grow faster and longer in length so its always better to wide bottom flask to provide them enough space to grow.
I would isolate numerous mono clonal cultures by picking one cell per 48 well plate willed with f/2 at a similar salinity as the seed population. I think the key is replication. You could pay attention to the temperature (21*C should be good) and the light conditions. would start with well plates and then move onto larger vessels such as Erlenmeyer flasks. Many phytos will have a density threshold after which they will grow well so make sure that once the culture starts growing you don't dilute them down too much.
Hi,
The problem in cultivating diatoms over longer time periods is connected to their life cycle. The cell wall (frustel) of diatoms is built by two parts, the larger epitheca and the smaller hypotheca.
During division, the smaller part of the cell wall is newly synthesized, which results after one division in one daughter cell which has the same size like the mother cell and a 2nd daughter cell, which is smaller (the hypotheca of the mother cell becomes the epitheca of the daughter cell and a new smaller hypotheca is constructed). Each division results in smaller cells until a so-called "minimum size" is reached. Here sexual reproduction is essential, which will result in a big zygote (=auxospore) and then in large vegetative cells. Triggering sexual reproduction during cultivation is very hard, therefore diatom cultures usually die after some weeks/months.
If you go to catalogues of culture collections (UTEX, SAG, CCAP,...) you will realize that only a few diatom cultures are offered - now you know the reason.