Fed-batch fermentation of mixed carbon source significantly enhances the production of docosahexaenoic acid in Thraustochytriidae sp. PKU#Mn16 by differentially regulating fatty acids biosynthetic pathways

Huike Ye; Yaodong He; Yunxuan Xie; Biswarup Sen; Guangyi Wang

doi:10.1016/j.biortech.2019.122402

Fed-batch fermentation of mixed carbon source significantly enhances the production of docosahexaenoic acid in Thraustochytriidae sp. PKU#Mn16 by differentially regulating fatty acids biosynthetic pathways

Bioresour Technol. 2020 Feb:297:122402. doi: 10.1016/j.biortech.2019.122402. Epub 2019 Nov 11.

Authors

Huike Ye¹, Yaodong He¹, Yunxuan Xie¹, Biswarup Sen², Guangyi Wang³

Affiliations

¹ Center for Marine Environmental Ecology, School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China; Qingdao Institute Ocean Engineering of Tianjin University, Qingdao 266237, China.
² Center for Marine Environmental Ecology, School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China.
³ Center for Marine Environmental Ecology, School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China; Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China; Qingdao Institute Ocean Engineering of Tianjin University, Qingdao 266237, China. Electronic address: gywang@tju.edu.cn.

PMID: 31761627
DOI: 10.1016/j.biortech.2019.122402

Abstract

This study reports comparative evaluation of the growth and DHA productivity of the thraustochytrid strain Thraustochytriidae PKU#Mn16 fermented with seven different substrate feeding strategies. Of these strategies, fed-batch fermentation of the mixed substrate (glucose & glycerol) yielded the maximum growth (52.2 ± 1.5 g/L), DHA yield (Y_p/s: 8.65) and productivity (100.7 ± 2.9 mg/L-h), comparable with those of previously reported Aurantiochytrium strains. Transcriptomics analyses revealed that glucose upregulated some genes of the fatty acid synthase pathway whereas glycerol upregulated a few genes of the polyketide synthase pathway. Co-fermentation of the mixed substrate differentially regulated genes of these two pathways and significantly enhanced the DHA productivity. Furthermore, some genes involved in DNA replication, phagosome, carbon metabolism, and β-oxidation were also found to alter significantly during the mixed-substrate fermentation. Overall, this study provides a unique strategy for enhancing growth and DHA productivity of the strain PKU#Mn16 and the first insight into the mechanisms underlying mixed-substrate fermentation.

Keywords: Batch fermentation; Biomass; Bioreactor; FAS pathway; PKS pathway; Transcriptome.

MeSH terms

Biosynthetic Pathways
Carbon*
Docosahexaenoic Acids*
Fatty Acids
Fermentation

Substances

Fatty Acids
Docosahexaenoic Acids
Carbon