title: Effects of temperature on the astaxanthin productivity and light harvesting characteristics of the green alga Haematococcus pluvialis.
abstract: The green alga Haematococcus pluvialis, which accumulates astaxanthin at an optimal temperature of 20°C, was cultivated under temperatures of 20°C, 23.5°C, 27°C, and 30.5°C, in order to assess the effects on algal metabolism during the growth phase. The culture growth rate declined with above-optimal increases in temperature, and the final maximum cell concentration at 30.5°C reached only 35% of that attained at 20°C. On the contrary, the biomass productivity was increased under all the high-temperature conditions, probably reflecting the metabolism switch from cell duplication to energy accumulation that is typically observed in algal cultures subjected to environmental stress. Moreover, an increase in the light-harvesting capability of the alga was observed by means of the total pigment balance and the photosynthesis-intensity (PI) curve measured under the different cultivation conditions. Cultures kept at higher temperatures were able to better harvest and utilize the impinging light due to photo-acclimation. Finally, the differences in the astaxanthin metabolism were elucidated by subjecting the cultures to nitrogen starvation at 20°C and 27°C. In the culture at 27°C, a 1.4-fold increase in the astaxanthin productivity was observed when compared to that at 20°C, and the latter required almost two-fold more energy for the astaxanthin production compared with the 27°C culture.
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Luca
authors.initials: L
authors.lastname: Giannelli
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamada
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan. Electronic address: katsuda@kobe-u.ac.jp.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Katsuda
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Yamaji
mesh_terms: D018533:Biomass; D019149:Bioreactors / Q000191:economics; D000460:Chlorophyta / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D008027:Light; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000528:radiation effects; D013696:Temperature; D024341:Xanthophylls / Q000096:biosynthesis
chemical_list: D024341:Xanthophylls; C005948:astaxanthine; D009584:Nitrogen
keywords: Astaxanthin; Haematococcus pluvialis; Photobioreactor; Photosynthetic efficiency