Edition 3-4.03
– July 2017
Personal bioreactor RTS-1 & RTS-1C
Page 10
Operating instructions
8.2.1. Legend of experiment (fig. 5.): Personal Bioreactor RTS-1 / RTS-1C was used with 850 nm LED, volume of LB media in 50 ml
Falcon tube was 15 ml, Reverse Spin Frequency 1, 2, 4, 8, 16, 30 s
-1
, measurement frequency (MF) is 10 min
-1
, reactor rotation
speed 2000 rpm , t
emperature 37° C, diameter of filter pores (for aeration) 0.25 μm.
Figure 5. Influence of Frequency of Reverse Spinning on the
Growth kinetics (ΔOD
λ=850nm
/Δt) vs Time of fermentation (h).
Figure 6. Influence of Frequency of Reverse Spinning on the
Gro
wth kinetics (ΔOD
λ=850nm
/Δt) vs Time of fermentation (h).
8.3.
Aeration and types of recommended tubes.
For aerobic microorganisms, it is recommended to use tubes that are supplied by TPP - TubeSpin
®
Bioreactor 50ml. For obtaining
optimal results growing aerotolerant anaerobes, it is required to seal the screw cap of TPP TubeSpin
®
Bioreactor 50ml by tape.
User can also use standard centrifuge tubes of 50 ml Falcon type, taking into account that the tube material will be as transparent
as TPP TubeSpin
®
Bioreactor tube.
8.4.
Factory calibration particle size and calibration coefficients 600nm/850nm
Factory calibration of the instrument is designed for specific microorganism size of 0.4-0.8 x 1-
3 μm and a cell volume of approx-
imately 0.5-5.0
μm
3
. In case of exceeding the allowable size, the measurement system will not work correctly.
Optical density OD
λ=850 nm
to OD
λ=600 nm
conversion rate coefficient is equal to 1.9 (cells taken for measurement from stationary
phase using a spectrophotometer and 1mm optical path cuvette)
Example of calculation: to convert 3.5 OD
λ = 850 nm
to OD
λ = 600 nm
, multiply the result by 1.9, resulting in 6.65 OD
λ = 600 nm
.
The microorganism that used for factory calibration is E.coli BL21. The cells are taken from shake flask night culture at stationary
phase of growth.
8.5.
Factory calibration growth phase influence on measurement accuracy
During the growth transition of Escherichia coli culture from the exponential growth to the stationary phase, a number of morpho-
logical and physiological changes take place, including cell volume decrease and cell shape change. Therefore, if cells taken for
referent measurement using spectrophotometer at different stages from stationary phase then the correctness of measurement
will be worse than specified.
8.6.
Conversion rate coefficient of user calibration
Optical density OD
λ = 850 nm
to OD
λ = 600 nm
conversion rate coefficient depends on the cell size and volume. Therefore, the coefficient
will be different for other cell size and volume. The device can be calibrated at desired reference wavelength to meet the needs
of the user.
