Chin J Plan Ecolo ›› 2016, Vol. 40 ›› Issue (9): 933-941.DOI: 10.17521/cjpe.2015.0261

• Research Articles • Previous Articles     Next Articles

Response of growth and inorganic carbon utilization to different light and CO2 levels in Chlorella pyrenoidosa

Jia SHEN, Ya-He LI, Lin ZHANG, Xue SUN*()   

  1. School of Marine Sciences, Ningbo University
    Key Laboratory of Marine Biotechnology, Zhejiang Province, Ningbo, Zhejiang 315211, China
  • Received:2015-07-08 Accepted:2016-04-25 Online:2016-09-10 Published:2016-09-29
  • Contact: Xue SUN


AimsCarbon concentrating mechanism (CCM) is one of the important contents in algal physiology and ecology. Numerous studies have been carried out in eukaryotic and prokaryotic algae, but the information on economic microalga Chlorella pyrenoidosa (Chlorophyta) is limited. Our purpose is to explore the composite effect of light and CO2 on growth, inorganic carbon utilization in C. pyrenoidosa, and enrich the data on CCM in green algae.
Methods Two light intensities (40 and 120 µmol photons•m-2•s-1) and two CO2 concentrations (0.04% and 0.16%) were combined into four treatments, and then the algal growth, inorganic carbon concentration, pH compensation point, photosynthetic oxygen evolution rate, carbonic anhydrase (CA) activity and α-CA gene expression were investigated.
Important findings Chlorella pyrenoidosa grew fastest under the high-light and high-CO2 condition. The total inorganic carbon concentration under low-light and high-CO2 group was 1163.3 µmol·L-1, which was significantly higher than that of other three groups. The alga had the maximal pH compensation point of 9.8 under the high-light and low-CO2 condition, and the minimal pH compensation point of 8.6 under the low-light and high-CO2 condition. The maximum photosynthetic rate (Vmax) and inorganic carbon concentration in half maximum photosynthetic rate (K0.5) in the low-light and high-CO2 group were the highest, which were 1.28-1.91 times and 1.61-2.00 times of that in other three groups, respectively. The highest activity of extracellular CA was detected in the high-light and lower-CO2 group. However, α-CA gene expression reached the maximum under the low-light and low-CO2 condition. The results indicated that the low CO2 level could increase the algal pH compensation point, photosynthetic inorganic carbon affinity, and induce the external CA activity and α-CA gene expression in C. pyrenoidosa. HCO3- was used as the primary inorganic carbon source, and the inorganic carbon utilization was also regulated by light in C. pyrenoidosa.

Key words: Chlorella pyrenoidosa, light, CO2 concentration, inorganic carbon affinity