Correlating Gene Expression Profiles to Lipid Induction in the Microalga Chlorella protothecoides

Abstract

Microalgae are a promising source for sustainable biofuel production, but large‐scale production can be cost‐prohibitive. An understanding of the relationship between algal genome and metabolic pathways could serve to decrease cost and increase commercial viability. In this study, we examine the relationship between gene expression and lipid induction in Chlorella protothecoides. Using NextGen sequencing, we identified candidate genes, which were differentially expressed in algae grown in nitrogen sufficient (low lipid production) and nitrogen deficient (high lipid production) conditions. Using TaqMan real‐time PCR, differential expression was confirmed and quantified for each candidate gene in algae grown in media of varying nitrogen concentrations, and patterns of expression were defined. Systematic alterations were then made in pH, light, and micronutrients, and new expression profiles were generated. These expression profiles were correlated with cellular concentrations of lipids measured by lipid stain and flow cytometry to establish a distinct gene expression profile for lipid producing C. protothecoides. These expression profiles provide insight into C. protothecoides specific lipid production pathways. In addition, these lipid induction profiles are currently being used to rapidly assess the impact of environmental factors on lipid production days before detectable lipid production would be quantified.Support or Funding InformationResearch Scholars Program, Kentucky NSF EPScOR