Genetically Engineered Microalgae for Enhanced Biofuel Production

Background: Algae are currently considered among the most promising sources of raw materials for biodiesel production. Exceptional characteristics of some algal species and strains allow to reach more than 80% of neutral lipids; meanwhile, it should be taken into account that algal cultures do not need arable lands, they are undemanding to the sources of nutrition, being able of fast accumulation of biomass, and having a number of other advantages. However, if the aim is to get price-competitive raw material from them, it is not enough just to select natural strains - it is necessary to apply additional efforts to improve useful characteristics of these organisms. In-depth understanding of the lipid metabolism pathways in bacterial and eukaryotic cells has already allowed transferring this knowledge to microalgae in order to manipulate the expression of key genes responsible for enhancing their cellular oil content and oil quality. This review aims to show how genetic engineering efforts can change quantity and quality of microalgae lipids and make other changes on the transformed cells. Methods: We carried out a goal-directed analysis of bibliographic databases to generalize main results in genetic engineering of microalgae lipids pathways. Deductive qualitative content analysis methodology was used to analyze the papers. Results: Results of different methods of algal transformation by constructions that contain genes responsible for metabolism of lipids, which could be influential upon the competitive pathways of lipids biosynthesis and biosynthesis of their precursors, are compared and discussed. It is concluded that methods of genetic engineering allowed receiving the strains of microalgae with increased capability to accumulate lipids, changing their composition and improving algal growth characteristics. Conclusion: The analyzed data gives a better understanding of the metabolic pathways of lipids in microalgae, the ways of their regulation for the purpose of creating high-technology strains for producing of raw material for biodiesel production using not only traditional genetic engineering approaches, but also through projection of these efforts via extending possibilities of genomic engineering, including the potential of synthetic biology.