Microscale profiling of photosynthesis-related variables in a highly productive biofilm photobioreactor.

In the present study depth profiles of light, oxygen, pH and photosynthetic performance in an artificial biofilm of the green alga Halochlorella rubescens in a porous substrate photobioreactor (PSBR) were recorded with microsensors. Biofilms were exposed to different light intensities (50-1,000 μmol photons m(-2) s(-1) ) and CO2 levels (0.04-5% v/v in air).

Microscopic oxygen imaging based on fluorescein bleaching efficiency measurements.

Photobleaching of the fluorophore fluorescein in an aqueous solution is dependent on the oxygen concentration. Therefore, the time-dependent bleaching behavior can be used to measure of dissolved oxygen concentrations. The method can be combined with epi-fluorescence microscopy.