title: Cellular capacities for high-light acclimation and changing lipid profiles across life cycle stages of the green alga Haematococcus pluvialis.
abstract: The unicellular microalga Haematococcus pluvialis has emerged as a promising biomass feedstock for the ketocarotenoid astaxanthin and neutral lipid triacylglycerol. Motile flagellates, resting palmella cells, and cysts are the major life cycle stages of H. pluvialis. Fast-growing motile cells are usually used to induce astaxanthin and triacylglycerol biosynthesis under stress conditions (high light or nutrient starvation); however, productivity of biomass and bioproducts are compromised due to the susceptibility of motile cells to stress. This study revealed that the Photosystem II (PSII) reaction center D1 protein, the manganese-stabilizing protein PsbO, and several major membrane glycerolipids (particularly for chloroplast membrane lipids monogalactosyldiacylglycerol and phosphatidylglycerol), decreased dramatically in motile cells under high light (HL). In contrast, palmella cells, which are transformed from motile cells after an extended period of time under favorable growth conditions, have developed multiple protective mechanisms--including reduction in chloroplast membrane lipids content, downplay of linear photosynthetic electron transport, and activating nonphotochemical quenching mechanisms--while accumulating triacylglycerol. Consequently, the membrane lipids and PSII proteins (D1 and PsbO) remained relatively stable in palmella cells subjected to HL. Introducing palmella instead of motile cells to stress conditions may greatly increase astaxanthin and lipid production in H. pluvialis culture.
authors.affiliation: Department of Chemical and Biochemical Engineering, Xiamen University, Xiamen, Fujian, China; Department of Human System and Environment, Arizona State University, Mesa, Arizona, United States of America.
authors.forename: Baobei
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Human System and Environment, Arizona State University, Mesa, Arizona, United States of America; State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Hu
authors.affiliation: Department of Human System and Environment, Arizona State University, Mesa, Arizona, United States of America.
authors.forename: Milton
authors.initials: M
authors.lastname: Sommerfeld
authors.affiliation: Department of Chemical and Biochemical Engineering, Xiamen University, Xiamen, Fujian, China.
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Human System and Environment, Arizona State University, Mesa, Arizona, United States of America.
authors.forename: Danxiang
authors.initials: D
authors.lastname: Han
mesh_terms: D000064:Acclimatization; D020418:Algal Proteins / Q000378:metabolism / Q000502:physiology; D002465:Cell Movement; D000460:Chlorophyta / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D004579:Electron Transport; D008027:Light; D050356:Lipid Metabolism; D010788:Photosynthesis / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000378:metabolism / Q000502:physiology; D010860:Pigments, Biological / Q000737:chemistry
chemical_list: D020418:Algal Proteins; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological