Phytoplankton fluorescence:
From ecophysiology to biotechnology

Sebastian Lippemeier
University of Kiel, Germany

Friday, April 30, 1999
12:00 Noon—Pacific Forum

The detection of chlorophyll fluorescence has provided new insights in the regulation of phytoplankton photosynthesis. In several ecophysiological studies, it could be shown that the fluorescence parameters allow an assessment of photosynthetic capacity, which is comparable to the results obtained with classical techniques (e.g. ¹⁴C, O₂).

After a brief introduction of the PAM-fluorescence technique, on and off-line measurements of fluorescence will be presented to demonstrate the close relationships between different nutrient limitations (silicate, nitrogen, phosphate) and the fluorescence signals.

Based on these relationships, a new concept for a physiologically controlled photobioreactor (physiostat) for microalgae is presented. In contrast to conventional cultivation techniques, the physiostat will provide an on-line control of algal growth via a physiological feedback on the basis of specific fluorescence signals. This is the prerequisite for an effective use of microalgae in biotechnology, because the synthesis rate of many valuable biosubstances is closely connected to different factors like nutrient limitation that directly influence algal growth. As a consequence, the physiostat system will provide a controlled and flexible manipulation of the growth regulating factors and thus allows the cultivation of microalgae in an optimal environment for most effective productivity at any time.

Next: Chemical ecology of deep-sea animals- Searching for food in the dark