Time-resolved Transcriptome Analysis and Lipid Pathway Reconstruction of the Oleaginous Green Microalga Reveal a Model for Triacylglycerol and Lipid Hyperaccumulation

Overview

Journal Biotechnol Biofuels

Publisher Biomed Central

Specialty Biotechnology

Date 2017 Aug 18

PMID 28814974

Citations 14

Authors

Daniel Jaeger

Anika Winkler

Jan H Mussgnug

Jorn Kalinowski

Alexander Goesmann

Olaf Kruse

Affiliations

Soon will be listed here.

Abstract

Background: Oleaginous microalgae are promising production hosts for the sustainable generation of lipid-based bioproducts and as bioenergy carriers such as biodiesel. Transcriptomics of the lipid accumulation phase, triggered efficiently by nitrogen starvation, is a valuable approach for the identification of gene targets for metabolic engineering.

Results: An explorative analysis of the detailed transcriptional response to different stages of nitrogen availability was performed in the oleaginous green alga . Transcript data were correlated with metabolic data for cellular contents of starch and of different lipid fractions. A pronounced transcriptional down-regulation of photosynthesis became apparent in response to nitrogen starvation, whereas glucose catabolism was found to be up-regulated. An in-depth reconstruction and analysis of the pathways for glycerolipid, central carbon, and starch metabolism revealed that distinct transcriptional changes were generally found only for specific steps within a metabolic pathway. In addition to pathway analyses, the transcript data were also used to refine the current genome annotation. The transcriptome data were integrated into a database and complemented with data for other microalgae which were also subjected to nitrogen starvation. It is available at https://tdbmn.cebitec.uni-bielefeld.de.

Conclusions: Based on the transcriptional responses to different stages of nitrogen availability, a model for triacylglycerol and lipid hyperaccumulation is proposed, which involves transcriptional induction of thioesterases, differential regulation of lipases, and a re-routing of the central carbon metabolism. Over-expression of distinct thioesterases was identified to be a potential strategy to increase the oleaginous phenotype of , and furthermore specific lipases were identified as potential targets for future metabolic engineering approaches.

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