Harnessing the Power of Mutagenesis and Adaptive Laboratory Evolution for High Lipid Production by Oleaginous Microalgae and Yeasts

Abstract

Oleaginous microalgae and yeasts represent promising candidates for large-scale production of lipids, which can be utilized for production of drop-in biofuels, nutraceuticals, pigments, and cosmetics. However, low lipid productivity and costly downstream processing continue to hamper the commercial deployment of oleaginous microorganisms. Strain improvement can play an essential role in the development of such industrial microorganisms by increasing lipid production and hence reducing production costs. The main means of strain improvement are random mutagenesis, adaptive laboratory evolution (ALE), and rational genetic engineering. Among these, random mutagenesis and ALE are straight forward, low-cost, and do not require thorough knowledge of the microorganism’s genetic composition. This paper reviews available mutagenesis and ALE techniques and screening methods to effectively select for oleaginous microalgae and yeasts with enhanced lipid yield and understand the alterations caused to metabolic pathways, which could subsequently serve as the basis for further targeted genetic engineering.

Fatty Acids Derivatives From Eukaryotic Microalgae, Pathways and Potential Applications

“…ALE is based on the natural selection of specific populations that acquire beneficial mutations under the pressure of prolonged stress conditions (light, pH, salinity). Such strategy is a powerful tool to yield phenotypes with interesting features such as faster growth and higher lipid content, even when genomes and metabolic pathways are unknown ( Arora et al, 2020 ). In the context of PUFA production, ALE approach has been applied to different species and revealed promising results.…”

Highly Valuable Polyunsaturated Fatty Acids from Microalgae: Strategies to Improve Their Yields and Their Potential Exploitation in Aquaculture

“…The random mutagenesis approach carried out throughout physical or chemical mutagens can be applied to species for which genetic transformations are not possible. This method causes alterations to the organism's DNA, followed by selection of mutants with the desired metabolic properties [86].…”

“…Although random mutagenesis produced a lot of interesting results [86], the recent development of nuclear transformation and the availability of genome sequences for an increasing number of model species contributed to enlarge the collection of tools for targeted mutagenesis allowing overexpression and knock-down or knock-out of specific target genes in microalgae.…”

Algal glycobiotechnology: omics approaches for strain improvement

“…Generally, industries use random mutagenesis and spontaneous mutation followed by intelligent screening process to construct an improved strain with desired properties. In the past, increasing production of the target molecule(s) was achieved using traditional techniques such as media manipulation, cultural techniques, improved downstream and extraction processes and, random mutagenesis by physical, chemical and ultraviolet methods [ 6 ]. In several cases, metabolic engineering have been successful for the strain improvement however, strain improvement of algae through metabolic engineering is still at an early stage and requires substantial development [ 7 ].…”