Publication details
Photobioreactor for cultivation and real-time, in-situ measurement of O-2 and CO2 exchange rates, growth dynamics, and of chlorophyll fluorescence emission of photoautotrophic microorganisms
| Authors | |
|---|---|
| Year of publication | 2009 |
| Type | Article in Periodical |
| Magazine / Source | ENGINEERING IN LIFE SCIENCES |
| Citation | |
| Doi | http://dx.doi.org/10.1002/elsc.200800123 |
| Keywords | Bioreactor; Biotechnology; CO2 sequestration; Photosynthesis |
| Description | A detailed knowledge about the dynamics of phytoplanktonic photosynthesis and respiration is crucial for the determination of primary productivity in open oceans as well as for biotechnological applications. The dynamics are best studied in photobioreactors that are able to simulate natural conditions in such, that light can be modulated not only diurnally but also mimicking effects of solar elevation angle from sunrise to sunset, variable cloudiness, light modulation in refractory sun flecks due to water waves, or light intermittence due to turbulent flow in dense suspensions. In addition, high performance photobioreactors ought to be able to monitor in real time photosynthetic and respiratory activities as well as culture growth. Here, we demonstrate performance of a newly designed bench-top laboratory photobioreactor that meets these needs, with a study of green alga Scenedesmus quadricauda. The algal suspension was exposed to simulated daily variations of total photosynthetic active irradiance and spectral profile, with a larger proportion of red photons in the morning and evening hours. The instrument monitored automatically the culture growth by measuring the optical densities at 735 nm and 680 rim and by measuring steady state and maximal chlorophyll fluorescence emission yields. The photochemical yields were estimated from chlorophyll fluorescence data. These widely used but rather indirect yield estimates were confronted with direct measurements of oxygen evolution and consumption quantum yields. The CO2 fluxes in and out of the culture media as well as the dissolved CO2 in algal suspension were also recorded. The experiments demonstrated potential of the new photobioreactor to reveal minute modulations in gas exchange rates as well as to yield data for calculation of photon requirement of oxygen evolution in the suspension volume that is key technological parameter for planning of large scale photobioreactors as well as key optimization parameter for strain selection. |