Bioengineering of Microalgae: Recent Advances, Perspectives, and Regulatory Challenges for Industrial Application

Abstract

Microalgae, due to their complex metabolic capacity, are being continuously explored for nutraceuticals, pharmaceuticals, and other industrially important bioactives. However, suboptimal yield and productivity of the bioactive of interest in local and robust wild-type strains are of perennial concerns for their industrial applications. To overcome such limitations, strain improvement through genetic engineering could play a decisive role. Though the advanced tools for genetic engineering have emerged at a greater pace, they still remain underused for microalgae as compared to other microorganisms. Pertaining to this, we reviewed the progress made so far in the development of molecular tools and techniques, and their deployment for microalgae strain improvement through genetic engineering. The recent availability of genome sequences and other omics datasets form diverse microalgae species have remarkable potential to guide strategic momentum in microalgae strain improvement program. This review focuses on the recent and significant improvements in the omics resources, mutant libraries, and high throughput screening methodologies helpful to augment research in the model and non-model microalgae. Authors have also summarized the case studies on genetically engineered microalgae and highlight the opportunities and challenges that are emerging from the current progress in the application of genome-editing to facilitate microalgal strain improvement. Toward the end, the regulatory and biosafety issues in the use of genetically engineered microalgae in commercial applications are described.

Advances in the biological fixation of carbon dioxide by microalgae

“…By overexpressing an aldolase, the C cycle can be accelerated, and CO 2 can be better fixed. Additionally, overexpressing the SBPase gene and RuBisCO activase gene in microalgae speeding up the Calvin Cycle has been reported in many studies, resuling in enhanced capabilities in C fixation and photosynthesis 131–134 …”

“…Moreover, reducing the light‐harvesting complex (LHC) antenna size can alleviate excess absorption of sunlight and the ensuing wasteful dissipation of excitation energy, thereby enhancing photosynthesis efficiency 124, 133 . Genes that can reduce LHC protein synthesis, such as lciA and nabI* , have been successfully expressed in some microalgae and have improved photosynthetic efficiency and C sequestration 135 .…”

Seaweeds and microalgae: an overview for unlocking their potential in global aquaculture development

“…Microalgae cultivation, which usually rears non-toxic microalgae in self-contained farming systems, presents low risks of causing harmful algae blooms in wild habitats. However, precautionary measures should be taken to minimize such risks, especially as genetic modification has been considered as a means to increase the productivity of microalgae cultivation (Henley et al, 2012;Kumar et al, 2020).…”

Use of <em>Dunaliella salina</em> in Environmental Applications <sup>†</sup>

“…Algae are the oldest microorganisms that have a simple photosynthetic cell structure and a high content of chlorophyll [1,2]. Macro-and micro-scale algae are quite widely used in environmental and biotechnological applications due to their unique natural properties [3,4]. Algal groups (Cholophyceae, Rhodophyceae, Cyanophyceae, and Pheophyceae) are aquatic creatures that can be found in many parts of the world and vary in size from 3-10 μ to 70 cm [5][6][7].…”