TY - JOUR
T1 - Enhanced protection against oxidative stress in an astaxanthin- overproduction Haematococcus mutant (Chlorophyceae)
AU - Hu, Zhengyu
AU - Li, Yantao
AU - Sommerfeld, Milton
AU - Chen, Feng
AU - Hu, Qiang
N1 - Funding Information:
We thank Dr S.B. Wang and Dr G.X. Liu for carrying out the mutagenesis and screening for the Haematococcus mutant, and Drs Zhi Li and Yung Chang for technical support for analysing the flow cytometry data. This work was partially funded by the Science Foundation Arizona’s Small Business Catalytic Program.
PY - 2008/11
Y1 - 2008/11
N2 - Many unicellular green algae can become yellow or red in various natural habitats due to mass accumulation of a secondary carotenoid, such as lutein, or astaxanthin. The accumulation of secondary carotenoids is generally thought to be a survival strategy of the algae under photo-oxidative stress or other adverse environmental conditions. The physiological role of the carotenoids in stress response is less well understood at the subcellular or molecular level. In this study, a stable astaxanthin overproduction mutant (MT 2877) was isolated by chemical mutagenesis of a wild type (WT) of the green microalga Haematococcus pluvialis Flotow NIES-144. MT 2877 was identical to the WT with respect to morphology, pigment composition, and growth kinetics during the early vegetative stage of the life cycle. However, it had the ability to synthesize and accumulate about twice the astaxanthin content of the WT under high light, or under high light in the presence of excess amounts of ferrous sulphate and sodium acetate. Under stress, the mutant exhibited higher photosynthetic activities than the WT, based on considerably higher chlorophyll fluorescence induction, chlorophyll autofluorescence intensities, and oxygen evolution rates. Cell mortality caused by stress was reduced by half in the mutant culture compared with the WT. Enhanced protection of the mutant against stress is attributed to its accelerated carotenogenesis and accumulation of astaxanthin. Our results suggest that MT 2877, or other astaxanthin overproduction Haematococcus mutants, may offer dual benefits, as compared with the wild type, by increasing cellular astaxanthin content while reducing cell mortality during stress-induced carotenogenesis.
AB - Many unicellular green algae can become yellow or red in various natural habitats due to mass accumulation of a secondary carotenoid, such as lutein, or astaxanthin. The accumulation of secondary carotenoids is generally thought to be a survival strategy of the algae under photo-oxidative stress or other adverse environmental conditions. The physiological role of the carotenoids in stress response is less well understood at the subcellular or molecular level. In this study, a stable astaxanthin overproduction mutant (MT 2877) was isolated by chemical mutagenesis of a wild type (WT) of the green microalga Haematococcus pluvialis Flotow NIES-144. MT 2877 was identical to the WT with respect to morphology, pigment composition, and growth kinetics during the early vegetative stage of the life cycle. However, it had the ability to synthesize and accumulate about twice the astaxanthin content of the WT under high light, or under high light in the presence of excess amounts of ferrous sulphate and sodium acetate. Under stress, the mutant exhibited higher photosynthetic activities than the WT, based on considerably higher chlorophyll fluorescence induction, chlorophyll autofluorescence intensities, and oxygen evolution rates. Cell mortality caused by stress was reduced by half in the mutant culture compared with the WT. Enhanced protection of the mutant against stress is attributed to its accelerated carotenogenesis and accumulation of astaxanthin. Our results suggest that MT 2877, or other astaxanthin overproduction Haematococcus mutants, may offer dual benefits, as compared with the wild type, by increasing cellular astaxanthin content while reducing cell mortality during stress-induced carotenogenesis.
KW - Astaxanthin
KW - Carotenogenesis
KW - Flow cytometry
KW - Haematococcus pluvialis
KW - Oxidative stress
KW - Pigment mutant
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U2 - 10.1080/09670260802227736
DO - 10.1080/09670260802227736
M3 - Article
AN - SCOPUS:57349161891
VL - 43
SP - 365
EP - 376
JO - British Phycological Journal
JF - British Phycological Journal
SN - 0967-0262
IS - 4
ER -