The role of microtubules in microalgae: promotion of lipid accumulation and extraction

Lijie Zhang; Xiao Lin; Zhigang Yang; Liqun Jiang; Qingjie Hou; Zhen Xie; Yizhen Li; Haiyan Pei

doi:10.1186/s13068-023-02257-8

The role of microtubules in microalgae: promotion of lipid accumulation and extraction

Biotechnol Biofuels Bioprod. 2023 Jan 12;16(1):7. doi: 10.1186/s13068-023-02257-8.

Authors

Lijie Zhang^#¹, Xiao Lin^#², Zhigang Yang¹, Liqun Jiang¹, Qingjie Hou¹, Zhen Xie¹, Yizhen Li¹, Haiyan Pei^{3

4

5}

Affiliations

¹ School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, China.
² Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK.
³ School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, China. haiyanhup@126.com.
⁴ Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China. haiyanhup@126.com.
⁵ Shandong Provincial Engineering Center on Environmental Science and Technology, Jinan, 250061, China. haiyanhup@126.com.

^# Contributed equally.

Abstract

Background: Microtubules in cells are closely related to the growth and metabolism of microalgae. To date, the study of microalgal microtubules has mainly concentrated on revealing the relationship between microtubule depolymerization and synthesis of precursors for flagellar regeneration. While information on the link between microtubule depolymerization and biosynthesis of precursors for complex organic matter (such as lipid, carbohydrate and protein), is still lacking, a better understanding of this could help to achieve a breakthrough in lipid regulation. With the aim of testing the assumption that microtubule disruption could regulate carbon precursors and redirect carbon flow to promote lipid accumulation, Chlorella sorokiniana SDEC-18 was pretreated with different concentrations of oryzalin.

Results: Strikingly, microalgae that were pretreated with 1.5 mM oryzalin accumulated lipid contents of 41.06%, which was attributed to carbon redistribution induced by microtubule destruction. To promote the growth of microalgae, two-stage cultivation involving microtubule destruction was employed, which resulted in the lipid productivity being 1.44 times higher than that for microalgae with routine single-stage cultivation, as well as yielding a desirable biodiesel quality following from increases in monounsaturated fatty acid (MUFA) content. Furthermore, full extraction of lipid was achieved after only a single extraction step, because microtubule destruction caused removal of cellulose synthase and thereby blocked cellulose biosynthesis.

Conclusions: This study provides an important advance towards observation of microtubules in microalgae through immunocolloidal gold techniques combined with TEM. Moreover, the observation of efficient lipid accumulation and increased cell fragility engendered by microtubule destruction has expanded our knowledge of metabolic regulation by microtubules. Finally, two-stage cultivation involving microtubule destruction has established ideal growth, coupling enhanced lipid accumulation and efficient oil extraction; thus gaining advances in both applied and fundamental research in algal biodiesel production.

Keywords: Cell fragility; Lipid accumulation; Microalgae; Microtubule destruction; Two-stage cultivation.

Abstract

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