Optimizing the growth of Haematococcus pluvialis based on a novel microbubble-driven photobioreactor

Kebi Wu; Kezhen Ying; Jin Zhou; Dai Liu; Lu Liu; Yi Tao; James Hanotu; Xiaoshan Zhu; Zhonghua Cai

doi:10.1016/j.isci.2021.103461

Optimizing the growth of Haematococcus pluvialis based on a novel microbubble-driven photobioreactor

iScience. 2021 Nov 15;24(12):103461. doi: 10.1016/j.isci.2021.103461. eCollection 2021 Dec 17.

Authors

Kebi Wu^{1

2}, Kezhen Ying^{2

3}, Jin Zhou², Dai Liu², Lu Liu^{1

2}, Yi Tao⁴, James Hanotu⁵, Xiaoshan Zhu², Zhonghua Cai^{1

2}

Affiliations

¹ School of Life Sciences, Tsinghua University, Beijing 100086, China.
² Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
³ Oasis Photobio Tech Ltd, Overseas Chinese Scholars Venture Building, South District of High-Tech Industrial Park, Shenzhen, China.
⁴ Guangdong Provincial Engineering Research Centre for Urban Water Recycling and Environmental Safety, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
⁵ Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield S13JD, UK.

Abstract

Haematococcus pluvialis, the richest bioresource for natural astaxanthin, encounters a challenge of achieving high growth rate when it comes to mass biomass production. Based on the substrate consumption model and Redfield ratio, rapid algae growth benefits from a proper carbon supply. However, the conventional cultivation schemes with limited carbon dioxide (CO₂) supply and inefficient carbon mass transfer could have constrained the carbon capture and growing ability of H. pluvialis. We hypothesize that optimal H. pluvialis growth improvement may be achieved by efficient CO₂ supply. Here, in this study, we first identified the carbon consumption of H. pluvialis during exponential growth. Then, a novel microbubble-driven photobioreactor (MDPBR) was designed to satisfy the carbon demand. The novel microbubble photobioreactor improves the CO₂ supply by reducing bubble size, significantly elevating the CO₂ mass transfer. With only 0.05 L min^-1 of gas flow rate, higher cell growth rate (0.49 d^-1) has been achieved in MDPBR.

Keywords: Biological sciences; Biotechnology; Microbial biotechnology.