Hi, eVOLVER experts
I am now setting some experiments, and found that I need 25 L for almost 5 days experiments ! (20 mL for culture volumes, 1.5 h for Avg.doubleing time, 16 for the number of cultures)
I calculated the required media by using the metrics in the Supplementary Notes 8 below.
Because it’s my first time with continuous culture, it is just surprising me.
Is 25 L for 5 days kind of normal volumes often used ??
Thank you very much for your help!
Best wished
Hi @sunachi,
If you are running a turbidostat, the media consumption will also depend on the cell density range you will be using e.g. for a lower_thres = 0.1 and higher_thres = 0.8, cells are growing for 3 generations without a dilution, so you will use a bit less medium.
I use the following formula to calculate my eVOLVER’s consumption:
experiment_time / time_between_dilutions * volume_per_dilution
which extends to the following:
days * 24 / ( LOG2 ( upper / lower ) * gtime ) * ( 1 - lower / upper ) * volume
You can also use this excel sheet.
Hope it helps!
Dani
@danigarcia Thanks for the tips!!
By the way, what is gtime in your extended formula ?
Bests,
sunachi
Generation time, so the same as doubling time in the formula from the paper.
Hi @danigarcia ,
It’s been a while since this post, but I’m thinking about it again.
In turbidostat in custom_script.py, the code is
-np.log e (lower_thres / Ave.OD) * volume / flow_rate
so, this means that required volume per dilution is
① -np.log e (lower_thres / Ave.OD) * volume
but in your reply above, it says
② ( 1 - lower / upper ) * volume
Which is more accurate for calculating the required volume per dilution, 1 or 2??
In my setups, the original code (i.e., ①) seems to work well, though.
Thanks!
sunachi
Hi @sunachi,
After giving it a thought, I believe the first one is the most accurate. While my approach is a linear approximation (it assumes we first remove the culture volume and then we add the fresh medium), the dilution follows an exponential, since the input and output run at the same time, so ① should be the most accurate!
Cheers!
Hey Dani,
Thank you very much!
