In vivo determination of carotenoid resonance excitation profiles of Chlorella vulgaris, Haematococcus pluvialis, and Porphyridium purpureum

Under stress, certain species of algae produce pigments such as astaxanthin, β‐carotene, or phycoerythrin for protection against photosynthethic stress. These pigments are of high commercial demand, for example, as food additives. Measuring and maintaining stress conditions precisely are necessary for efficient pigment synthesis in algae cultures. We present resonance excitation maps of three common species of algae, Chlorella vulgaris, Haematococcus pluvialis, and Porphyridium purpureum, exploring the feasibility of resonance Raman spectroscopy for stress monitoring in vivo. The resonance excitation profiles for individual Raman lines of carotenoids extracted from the resonance excitation maps of different stress states are a helpful guide to pick optimal excitation wavelengths for maximum resonance enhancement in living algae cultures of these species under laboratory conditions.