Team:ECUST/Part/Reactor

We found that the traditional light sources of photo reactor were mainly external light plate or built-in lamp, each of which had a defect. So we built a photobioreactor(Fig.1) with a light source placed in the agitator.


Figure 1. Structure of photobioreactor



Taking absorption and scattering of lights into consideration, we used cornet model (raised by cornet in 1992) to describe the light attenuation in photobioreactor. This model was based on two hypothesis: 1)lights in medium were isotropic; 2)Absorption and scattering of light were respectively determined by two independent coefficients (Ea and Es). A simplified function of cornet model is:


I: illuminance of different points in photobioreactor
I 0: illuminance of the light source=15000 lux
X: cell concentration=5.4 g/L
r: optical path, in centimeter
Ea: absorption coefficient
Es: scattering coefficient



After nonlinear fitting of light intensity data of different cell concentrations and different optical paths with MATLAB, absorption coefficient (0.0014 m2/g) and scattering coefficient (0.9002 m2/g) were available.




The relation between luminous flux(Φ) of a point that was r centimeters away from light source and illuminance(I) of the same point could be given by this formula:


According to Beer-Lambert Law,

ε[1]: molar extinction coefficient=101000 M-1 cm-1
c: concentration of fluorescent protein=2.32×10 -9 M



So the luminous flux(ΦsYFP2) absorbed by fluorescent protein was:



The luminous flux and the luminous power(PsYFP2) fitted the following formula[2]:

Km [2]: the ability of human eyes to sense light=683.002 lm/W
V(517)[2]: luminosity function when the wavelength of light is 517 nm.



The energy of one photon(517nm) is 3.84487×10-19 joules so number of photons(N) that fluorescent protein could absorb per second was:





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Reference

[1] Kremers G J, Goedhart J, van Munster E B, et al. Cyan and yellow super fluorescent proteins with improved brightness, protein folding, and FRET Förster radius.[J]. Biochemistry, 2006, 45(21):6570.
[2] https://en.wikipedia.org/wiki/Luminosity_function#cite_note-Charles2003-5