Turbidostat
Turbidostats are automated culturing systems used to maintain a constant cell density in microbial cultures.
OD is constantly monitored
When OD goes above the an upper OD threshold
A dilution is calculated to bring OD to the lower threshold
Dilutions are capped at 20 seconds to avoid vial overflow
Both influx and efflux pumps are run simultaneously for the calculated length
Efflux pumps are run extra to make sure volume stays constant
The efflux straw sets volume
Turbidostat Dilution
Influx and efflux are both run at the same time
Like chemostat, vial volume is set by efflux straw height
Efflux is run extra time to make sure that enough volume is removed
Dilution Calculation Example
Dilution is calculated in the code and is modeled as a mass balance equation
Example Dilution
time_in = -(np.log(lower_thresh[x]/average_OD) *VOLUME)/flow_rate[x]
However, the mox dilution is 20 seconds to avoid overflow.
Calculated in eVOLVER.py in function and stored in your data folder during an experiment.
When there is a turbidostat dilution, it fits a line to the log of the OD data since the last growth curve (ie last turbidostat dilution) time. The slope of that line is reported as the growth rate in 1/hr.
Convert growth rate to doubling time (in hours) via ln(2)/growthrate.
Growth Rate (1/hr)
Doubling Time (hr)
See and the for information.
