Transcriptome analysis reveals the genetic foundation for the dynamics of starch and lipid production in Ettlia oleoabundans

Authors
Sturme, Mark H.J.; Gong, Yanhai; Heinrich, Josué Miguel; Klok, Anne J.; Eggink, Gerrit; Wang, Dongmei; Xu, Jian; Wijffels, Rene H.
Publication Year
2018
Language
English
Format
article
Status
Published version
Description
The oleaginous microalga Ettlia oleoabundans accumulates both starch and lipids to high levels under stress conditions such as nitrogen starvation (N−). To steer biosynthesis towards starch or lipids only, it is important to understand the regulatory mechanisms involved. Here physiological and transcriptional changes under nitrogen starvation were analysed in controlled flat-panel photobioreactors at both short and long time-scales. Starch accumulation was transient and occurred rapidly within 24 h upon starvation, while lipid accumulation was gradual and reached a maximum after 4 days. The major fraction of accumulated lipids was composed of de novo synthesized neutral lipids - triacylglycerides (TAG) - and was characterized by a decreased composition of the polyunsaturated fatty acids (PUFAs) C18:3 and C16:3 and an increased composition of the mono-unsaturated (MUFAs) and saturated (SFAs) fatty acids C18:1/C16:1 and C18:0/C16:0, respectively. RNA-sequencing revealed that starch biosynthesis and degradation genes show different expression dynamics from lipid biosynthesis ones. An immediate rapid increase in starch synthetic transcripts was followed by an increase in starch degrading transcripts and a decrease in the starch synthetic ones. In contrast, increased gene expression for fatty acid and TAG synthesis was initiated later and occurred more gradually. Expression of several fatty acid desaturase (FAD) genes was decreased upon starvation, which corresponds to the observed changes to higher levels of MUFAs and SFAs. Moreover, several homologs of transcription regulators that were implicated in controlling starch and lipid metabolism in other microalgae showed differential gene expression and might be key regulators of starch and lipid metabolism in E. oleoabundans as well. Our data provide insights into the genetic foundation of starch and lipid metabolism in E. oleoabundans under nitrogen starvation and should facilitate metabolic engineering towards tailored strains with desired storage compound composition.
Fil: Sturme, Mark H.J.. University of Agriculture Wageningen; Países Bajos
Fil: Gong, Yanhai. Qingdao Institute Of Bioenergy And Bioprocess Technolog; China
Fil: Heinrich, Josué Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina
Fil: Klok, Anne J.. University of Agriculture Wageningen; Países Bajos
Fil: Eggink, Gerrit. University of Agriculture Wageningen; Países Bajos
Fil: Wang, Dongmei. Qingdao Institute Of Bioenergy And Bioprocess Technolog; China
Fil: Xu, Jian. Qingdao Institute Of Bioenergy And Bioprocess Technolog; China
Fil: Wijffels, Rene H.. University of Agriculture Wageningen; Países Bajos
Subject
CARBON-PARTITIONING
LIPIDS
MICROALGAE
NITROGEN STARVATION
STARCH
TRANSCRIPTOME
Bioproductos, Biomateriales, Bioplásticos, Biocombustibles, Bioderivados, etc.
Biotecnología Industrial
INGENIERÍAS Y TECNOLOGÍAS
Access level
Restricted access
License
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repository
CONICET Digital (CONICET)
Institution
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identifier
oai:ri.conicet.gov.ar:11336/86888