An analytical flat-plate photobioreactor with a spectrally attenuated light source for the incubation of phytoplankton under dynamic light regimes

An inexpensive and simple, analytical microalgal photobioreactor with a hig hly controllable, dynamic, spectrally attenuated light source is described. Spectral attenuation is achieved through the introduction of a variable th ickness of CuSO4 solution between the photobioreactor and a light source. T he level of liquid is precisely determined via a computer-controlled perist altic pump, which can be programmed to pump at a variety of rates. The resu ltant light fields consist of a wide range of irradiance intensities with c oncomitant spectral narrowing, which closely mimics modeled clear water att enuation patterns. Irradiance dynamics associated with virtually any mixing regime can be achieved. The culturing apparatus of the analytical photobio reactor is based on traditional flat-plate, photobioreactor design, but wit h several modifications: (1) The light path has been reduced to 1 cm to ass ure a uniform light field is experienced by all phytoplankton at relatively low cell densities; (2) carbon dioxide concentrations are kept constant th rough a negative feedback mechanism that pulses CO2 into a constant air str eam when culture media pH rises above a set point; (3) temperature is contr olled in a similar manner, through the addition of cooling water to a water jacket in response to an increase in culture media temperature. This desig n is intended for use in photophysiological and bio- physical studies of mi croalgae under highly controlled culture conditions. It should prove easily adaptable to any number of more complex configurations.