TY - JOUR
T1 - Effects of stepwise nitrogen depletion on carotenoid content, fluorescence parameters and the cellular stoichiometry of Chlorella vulgaris
AU - Zhang, Ping
AU - Li, Zhe
AU - Lu, Lunhui
AU - Xiao, Yan
AU - Liu, Jing
AU - Guo, Jinsong
AU - Fang, Fang
N1 - Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2017/6/15
Y1 - 2017/6/15
N2 - Stressful conditions can stimulate the accumulation of carotenoids in some microalgae. To obtain more knowledge of the stress response, we studied the effects of different N concentrations on unicellular content of carotenoids using Raman spectroscopic technique; cellular stoichiometric changes and the fluorescence parameters of Chlorella vulgaris were concomitantly studied. Initially, we optimized the Raman scattering conditions and demonstrated the feasibility of unicellular carotenoid analysis by Raman spectroscopic technique. The results showed that an integration time of 10 s, laser power at 0.1 mW and an accumulation time of 1 were the optimum conditions, and the peak height at 1523 cm− 1 scaled linearly with the carotenoid content in the range of 0.625–1440 mg/L with a recovery rate of 97% ~ 103%. In the experiment, seven different nitrogen levels ranging from 0 to 2.48 × 105 μg/L were imposed. Samples were taken at the start, exponential phase and end of the experiment. The results showed that nitrogen stress can facilitate the synthesis of carotenoids, while at the same time, excessive nitrogen stress led to lower proliferative and photosynthetic activity. Compared with carotenoids, chlorophylls were more sensitive to nitrogen stress; it declined dramatically as stress processed. There existed no significant differences for Fv/Fm among different nitrogen levels during the exponential phase, while in the end, it declined and a significant difference appeared between cells in 2.48 × 105 μg/L N and other experimental levels. Photosynthetic efficiency, namely the C/N mole ratio in algal cells, didnot significantly change during the exponential phase; however, apparent increases ultimately occurred, except for the stable C/N in BG11 medium. This increase matched well with the carotenoid decline, indicating that an increasing cellular C/N mole ratio can be used as an indicator of excessive stress in carotenoid production. Besides, there also existed an inverse correlation with ETRmax.
AB - Stressful conditions can stimulate the accumulation of carotenoids in some microalgae. To obtain more knowledge of the stress response, we studied the effects of different N concentrations on unicellular content of carotenoids using Raman spectroscopic technique; cellular stoichiometric changes and the fluorescence parameters of Chlorella vulgaris were concomitantly studied. Initially, we optimized the Raman scattering conditions and demonstrated the feasibility of unicellular carotenoid analysis by Raman spectroscopic technique. The results showed that an integration time of 10 s, laser power at 0.1 mW and an accumulation time of 1 were the optimum conditions, and the peak height at 1523 cm− 1 scaled linearly with the carotenoid content in the range of 0.625–1440 mg/L with a recovery rate of 97% ~ 103%. In the experiment, seven different nitrogen levels ranging from 0 to 2.48 × 105 μg/L were imposed. Samples were taken at the start, exponential phase and end of the experiment. The results showed that nitrogen stress can facilitate the synthesis of carotenoids, while at the same time, excessive nitrogen stress led to lower proliferative and photosynthetic activity. Compared with carotenoids, chlorophylls were more sensitive to nitrogen stress; it declined dramatically as stress processed. There existed no significant differences for Fv/Fm among different nitrogen levels during the exponential phase, while in the end, it declined and a significant difference appeared between cells in 2.48 × 105 μg/L N and other experimental levels. Photosynthetic efficiency, namely the C/N mole ratio in algal cells, didnot significantly change during the exponential phase; however, apparent increases ultimately occurred, except for the stable C/N in BG11 medium. This increase matched well with the carotenoid decline, indicating that an increasing cellular C/N mole ratio can be used as an indicator of excessive stress in carotenoid production. Besides, there also existed an inverse correlation with ETRmax.
KW - Carotenoids
KW - Cellular stoichiometry
KW - Chlorella vulgaris
KW - Nitrogen stress
KW - Raman spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=85015667025&partnerID=8YFLogxK
U2 - 10.1016/j.saa.2017.03.022
DO - 10.1016/j.saa.2017.03.022
M3 - 文章
C2 - 28319796
AN - SCOPUS:85015667025
SN - 1386-1425
VL - 181
SP - 30
EP - 38
JO - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
JF - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
ER -