Characterisation of a secondary carotenoid producer microalga of the genus Coelastrella

Some green microalgae synthesize secondary carotenoids as protecting agents under stress. These pigments have high value as feed supplement for aquaculture and as health products. The most promising pigment is astaxanthin, because of its antioxidant, antitumoral and anti-inflamatory properties. The most used natural source of this pigment is the microalga Haematococcus pluvialis. However this species grows slowly and lacks robustness for easy cultivation. Therefore, other species are investigated for astaxanthin production. Here, we identified a locally isolated strain as Coelastrella sp. that is a secondary carotenoid producer. [1] A known typical feature of this genus, that we could observed in the strain by scanning electron microcopy, is the presence of meridional ribs. [2] We analyzed the culture conditions and concluded that this strain grows both autotrophically and heterotrophically and is able of fast change in pigment composition under controlled stress conditions. Thanks to HPLC analyses, we determined that the strain accumulates a variety of secondary carotenoids, among which: astaxanthin, cantaxanthin and echinenone. Unidentified compounds will be further analyzed by mass spectrometry.