Lumostatic operation of bubble column photobioreactors for Haematococcus pluvialis cultures using a specific light uptake rate as a control parameter

This study proposes lumostatic operations using a specific light uptake rate (qe) as a control parameter in order to maintain a desirable light condition. As a model system, bubble column photobioreactors have been operated lumostatically for photoautotrophic cultivations of Haematococcus pluvialis. Lumostatic operations were conducted at three levels of specific light uptake rates (qe=1.5×10−8, 3×10−8, and 4.5×10−8 μE cell−1 s−1) and compared with constant light energy supply (I0=40, 90, and 140 μE m−2 s−1). In the case of the lumostatic operation at 4.5×10−8 μE cell−1 s−1, the cell concentration was enhanced over 250% than that obtained under constant light energy, without inducing astaxanthin accumulation. For the lumostat at qe of 3.0×10−8 μE cell−1 s−1, the cell concentration increased almost 200% than that of the control experiments. These results indicate that a specific light uptake rate can be a useful parameter for lumostatic operation of photobioreactors and that the productivity of vegetative stage can be greatly improved by regulating the light condition based on the specific light uptake rates.