Transcriptional control in microalgae: co-regulated fatty acid biosynthesis and carbon dioxide fixation

Microalgae are desirable candidates for performing about half of the World's organic carbon fixation and its conversion to essential metabolites of human metabolism, including polyunsaturated fatty acids (PUFAs). However, the yields of microalgal FAs produced naturally are typically insufficient to cover the expenses of their commercial utilization. To overcome this problem, gene engineering techniques have been used to change the activity of endogenous enzymes. This review aims to find knowledge about the mechanism of regulation of fatty acid (FA) biosynthesis and CO₂ fixation in microalgae. Firstly, this study discusses molecular strategies toward accelerating FA biosynthesis with a main emphasis on a critical review of transcriptional engineering. Some transcription factors (TFs) are known to increase FA content and related gene expression. However, a research gap is revealed toward understanding their regulatory mechanism and finding their role in regulating CO₂ fixation. Secondly, a critical review of studies on CO₂ fixation regulated by Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) and RuBisCo activase (RCA) disclosed that no studies have yet been reported about their transcriptional control. Thirdly, prospects are given on the genetic basis of parallel transcriptional regulation of genes involved in FA biosynthesis and CO₂ fixation in microalgae. This study should potentially provide considerable knowledge on developing eco-friendly and sustainable microalgae genetic resources to maximize the yield of value-added FAs using TF engineering.