Journal of Environmental Biology

Growth characteristics of shade-acclimated marine Chlorella vulgaris under high-cell-density conditions

T. Katayama¹, N. Nagao²*, M. Goto³, F. Md. Yusoff², S. Banerjee², M. Sato¹, K. Takahashi¹ and K. Furuya¹

¹Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan

²Laboratory of Marine Biotechnology, Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia

³Faculty of Science and Engineering, Soka University, Hachioji, Tokyo 192-8577, Japan

*Corresponding Author E-mail: norionagao@gmail.com

Key words

Chlorella vulgaris

high cell density

light intensity per cell

light-saturation index

shade acclimation

Publication Data

Paper received : 09.06.2017

Revised received : 25.10.2017

Re-revised received : 30.11.2017

Accepted : 28.12.2017

Abstract

Aim: To potentially improve the productivity of microalgae for mass culture, growth characteristics and light-saturation index (E_k) in the marine microalga Chlorella vulgaris were investigated under high-cell-density conditions grown in batch cultures. ??

Methodology: Potential changes in the growth characteristics and E_k in C. vulgaris were investigated during 4 weeks of cultivation. The algae was cultivated in a column reactor at 25^?С under a surface light intensity of 300 μE m⁻² s⁻¹ in a 12-hr light and 12-hr dark cycle. ???

Results: Cell density increased and reached 2.7 g-dw l⁻¹ by the end of culture with an areal production rate of 3.3 g-dw m⁻² day⁻¹. The specific growth rate reached a maximum of 0.41 day⁻¹ when the light intensity per cell was 7.9 μE g-dw⁻¹ s⁻¹. As the light intensity per cell decreased with increasing cell density, E_k decreased gradually during the first half of the culture period.

Interpretation: Chlorella vulgaris in this study had the ability to acclimate to shade conditions during high-cell-density cultivation, however, the photosynthetic efficiency decreased. High transformation efficiency of light energy for photosynthesis in shade-acclimated cells will help to exploit the mass culture of microalgae.

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