Pyropia Conchocelis: Potential as an Algal Source for Carotenoid Extraction

Abstract

As shade adapted organisms the conchocelis of Pyropia contain high concentrations of photosynthetic pigments, making the conchocelis a potential source for the extraction of bioactive pigments such as phycoerythrin, phycocyanin and carotenoids. The pigment content of Pyropia conchocelis in response to environmental factors is poorly known. Investigations were performed on the production of carotenoid pigments as a function of environmental variables by the conchocelis phase of Alaskan Pyropia species: Pyropia abbottiae, P. hiberna,P. tortaandP. sp. Conchocelis fragments were cultured under different irradiance, and nutrient concentrations for up to 60 days. Results indicate that carotenoid pigments were significantly affected by irradiance, nutrient concentrations and culture age, with some interactions of these factors. Carotenoid pigment content varied in a similar manner for each species. Light had the most obvious influence on carotenoid content. For all four species, the highest carotenoid content (3.4-7.0mggdw-1) generally occurred at 0-10µmol photonsm-2s-1. Higher irradiances, low nutrients and longer culture age generally caused a decline of carotenoid pigment content. There were significant differences in carotenoid pigment content for different species. P. abbottiae and P. sp. produced higher pigment content than the other two species. Maximal carotenoid content for P. abbottiae was 7.0mggdw-1. P. torta contained the least carotenoid pigment under all culture conditions. Carotenoid pigments remained highest under continuous darkness for as long as 60 days for all tested species. The present study investigated the effects of environmental variables on the carotenoid content of Porphyra conchocelis and determined the optimal cultural conditions, which would helpful for obtaining algal material with higher pigment content and extraction of high value pigment.