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Carotenoid Distribution in Living Cells of Haematococcus pluvialis (Chlorophyceae)

Journal Article · · PLoS ONE

Haematococcus pluvialis is a freshwater unicellular green microalga belonging to the class Chlorophyceae and is of commercial interest for its ability to accumulate massive amounts of the red ketocarotenoid astaxanthin (3,3'-dihydroxy-β,β-carotene-4,4'-dione). Using confocal Raman microscopy and multivariate analysis, we demonstrate the ability to spectrally resolve resonance–enhanced Raman signatures associated with astaxanthin and β-carotene along with chlorophyll fluorescence. By mathematically isolating these spectral signatures, in turn, it is possible to locate these species independent of each other in living cells of H. pluvialis in various stages of the life cycle. Chlorophyll emission was found only in the chloroplast whereas astaxanthin was identified within globular and punctate regions of the cytoplasmic space. Moreover, we found evidence for β-carotene to be co-located with both the chloroplast and astaxanthin in the cytosol. These observations imply that β-carotene is a precursor for astaxanthin and the synthesis of astaxanthin occurs outside the chloroplast. Finally, our work demonstrates the broad utility of confocal Raman microscopy to resolve spectral signatures of highly similar chromophores in living cells.

Research Organization:
Energy Frontier Research Centers (EFRC); Photosynthetic Antenna Research Center (PARC)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
DOE Contract Number:
SC0001035
OSTI ID:
1065620
Journal Information:
PLoS ONE, Journal Name: PLoS ONE Journal Issue: 9 Vol. 6; ISSN 1932-6203
Publisher:
Public Library of Science
Country of Publication:
United States
Language:
English