Transcriptomic and metabolomic analyses revealed regulation mechanism of mixotrophic Cylindrotheca sp. glycerol utilization and biomass promotion

Song Wang; Xiyi Zhou; Sha Wu; Mengkai Zhao; Zhangli Hu

doi:10.1186/s13068-023-02338-8

Transcriptomic and metabolomic analyses revealed regulation mechanism of mixotrophic Cylindrotheca sp. glycerol utilization and biomass promotion

Biotechnol Biofuels Bioprod. 2023 May 19;16(1):84. doi: 10.1186/s13068-023-02338-8.

Authors

Song Wang¹, Xiyi Zhou¹, Sha Wu^{1

2}, Mengkai Zhao^{1

2}, Zhangli Hu³

Affiliations

¹ Guangdong Technology Research Center for Marine Algal Bioengineering; Guangdong Provincial Key Laboratory for Plant Epigenetics; Shenzhen Engineering Laboratory for Marine Algal Biotechnology; Longhua Innovation Institute for Biotechnology; College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China.
² College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China.
³ Guangdong Technology Research Center for Marine Algal Bioengineering; Guangdong Provincial Key Laboratory for Plant Epigenetics; Shenzhen Engineering Laboratory for Marine Algal Biotechnology; Longhua Innovation Institute for Biotechnology; College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China. huzl@szu.edu.cn.

Abstract

Background: Diatoms have been viewed as ideal cell factories for production of some high-value bioactive metabolites, such as fucoxanthin, but their applications are restrained by limited biomass yield. Mixotrophy, by using both CO₂ and organic carbon source, is believed effective to crack the bottleneck of biomass accumulation and achieve a sustainable bioproduct supply.

Results: Glycerol, among tested carbon sources, was proved as the sole that could significantly promote growth of Cylindrotheca sp. with illumination, a so-called growth pattern, mixotrophy. Biomass and fucoxanthin yields of Cylindrotheca sp., grown in medium with glycerol (2 g L^-1), was increased by 52% and 29%, respectively, as compared to the autotrophic culture (control) without compromise in photosynthetic performance. As Cylindrotheca sp. was unable to use glycerol without light, a time-series transcriptomic analysis was carried out to elucidate the light regulation on glycerol utilization. Among the genes participating in glycerol utilization, GPDH1, TIM1 and GAPDH1, showed the highest dependence on light. Their expressions decreased dramatically when the alga was transferred from light into darkness. Despite the reduced glycerol uptake in the dark, expressions of genes associating with pyrimidine metabolism and DNA replication were upregulated when Cylindrotheca sp. was cultured mixotrophically. Comparative transcriptomic and metabolomic analyses revealed amino acids and aminoacyl-tRNA metabolisms were enhanced at different timepoints of diurnal cycles in mixotrophic Cylindrotheca sp., as compared to the control.

Conclusions: Conclusively, this study not only provides an alternative for large-scale cultivation of Cylindrotheca, but also pinpoints the limiting enzymes subject to further metabolic manipulation. Most importantly, the novel insights in this study should aid to understand the mechanism of biomass promotion in mixotrophic Cylindrotheca sp.

Keywords: Biomass; Cylindrotheca; Diatom; Fucoxanthin; Metabolome; Mixotrophy; Transcriptome.

Abstract

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