Insights into transcriptomics and metabolic engineering of microalgal systems for enhancing industrial and environmental applications.

Microalgae have significant potential for environmental applications, such as carbon sequestration and bioremediation, while also generating biomass and synthesizing a range of metabolites that can be utilized for various industrial applications. This paper focuses on the genes underlying photosynthesis, carbon fixation, lipid production, antioxidant synthesis, and pollutant uptake by reviewing research on the microalgal transcriptome. Transcriptomics have helped identify characteristic genes, such as rbcl, ACC, DGAT, PDS, PSY, CHY, LCY, and FAD, which are involved in key metabolic pathways, including the Calvin cycle, fatty acid synthesis, beta-oxidation, PUFA production, and pigment synthesis. After identifying the key genes, these pathways can be modulated through metabolic engineering to enhance the production of targeted metabolites. Thus, this paper further discusses emerging approaches used in the metabolic engineering of microalgal genomes to improve industrial applications, including bioremediation, carbon sequestration, biofuels, and nutraceuticals. Genetic engineering studies have successfully enhanced the potential of microalgae for various applications, especially strains of Nannochloropsis, Phaeodactylum, Chlamydomonas, and Chlorella, which are now being further explored. CRISPR has been identified as one of the most reliable techniques for transient expression and multiple-gene editing. Thus, various CRISPR-based techniques for industrial applications are discussed, along with their challenges and prospects.