Hello,
So...to keep them in the so called stationary phase I started to grow them in a "chemostat" or a continuous culture, where they receive daily rations of nutrients to keep them alive and going for a long time in a state of equilibrium (until the big carboy runs out of media that is).
It has been a while! I must apologize. I have been so busy I had no time to do anything. Busy doing what you may ask...erm...work! The most important experiments of my PhD career have started. I have set up 3 phytoplankton "continuous" cultures (in the pic) and I am now waiting for them to reach a "steady state".
Ok I think a brief explanation is in order. Well, phytoplankton are the little unicellular plants that live and drift in the ocean. There are many different species, of a variety of colours and sizes:
What they need to survive (like any plant), is light and nutrients dissolved in the water. The main nutrients they survive on are Carbon (C), Nitrogen (N) and Phosphorous (P) [Iron (Fe) too but in minor quantities].
We grow different species in the lab and in order to do that we have to make some nice nutritious seawater for them, full of those nutrients they like as well as vitamins and minerals. It's a bit like cooking, just mixing powders and/or solutions with strange names all in a bottle.
Anyway, if you grow them in a closed bottle, the little ones will go on absorbing all the nutrients in the water until they run out. Which means they will eventually die. That is called growth curve:
 |
| My continuous cultures |
Ok I think a brief explanation is in order. Well, phytoplankton are the little unicellular plants that live and drift in the ocean. There are many different species, of a variety of colours and sizes:
 |
| Batch cultures I grow to feed zooplankton |
What they need to survive (like any plant), is light and nutrients dissolved in the water. The main nutrients they survive on are Carbon (C), Nitrogen (N) and Phosphorous (P) [Iron (Fe) too but in minor quantities].
We grow different species in the lab and in order to do that we have to make some nice nutritious seawater for them, full of those nutrients they like as well as vitamins and minerals. It's a bit like cooking, just mixing powders and/or solutions with strange names all in a bottle.
Anyway, if you grow them in a closed bottle, the little ones will go on absorbing all the nutrients in the water until they run out. Which means they will eventually die. That is called growth curve:
 |
| http://microvet.arizona.edu/Courses/MIC205/Exams/05Exams/05Ex2key.htm It says bacterias on the side but the principle applies to phytoplankton too (over DAYS not hours). |
So...to keep them in the so called stationary phase I started to grow them in a "chemostat" or a continuous culture, where they receive daily rations of nutrients to keep them alive and going for a long time in a state of equilibrium (until the big carboy runs out of media that is).
I must confess, set one of those things up is not that easy, there are a lot of things that go wrong all the time and the stress levels riseeeeeee. Every day there is something new to sort out...one day I will get it perfect!
They are so colourful, nature is amazing.
Came across this while Googling about continuous culture and I must say, that's quite interesting work you do. Like you, I'm a PhD student working on microalgae. So this really struck a chord with me.
ReplyDelete