### Research progress in carbon neutrality oriented adaptive laboratory evolution of microalgae

Quanyu ZHAO

1. School of Pharmaceutical Science，Nanjing Tech University，Nanjing 211816，Jiangsu，China
• Received:2021-09-30
• Contact: Quanyu ZHAO

Abstract:

Microalgae biotechnology is one of the potential ways to realize carbon peaking and carbon neutrality. At present, microalgae have key problems such as low carbon sequestration efficiency, low photosynthetic transformation efficiency and low content of active components. There are also some technological problems which greatly limit the pace of its industrialization. Most microalgae can not tolerate more than 2% CO2. Besides 10-25% CO2, there are other pollutants such as NOx and SOx in industrial flue gas. These flue gas components will inhibit the growth of microalgae. If the tolerance of algal strains are not enhanced, microalgae can not achieve the goal of stable carbon sequestration. In order to solve the problems of microalgae industrialization, wastewater resources can be used to meet the water demand in microalgae cultivation, and the economy can be improved by growing high value-added products. It is necessary to construct new algae strains by means of biotechnology such as synthetic biology, and build a new technical route of carbon reduction or negative carbon according to the characteristics of microalgae carbon sequestration and metabolism. Adaptive laboratory evolution (ALE) has made some progress in improving CO2 fixation by microalgae, enhancing wastewater treatment and improving metabolic phenotype. Evolved algal strains resistant to high concentration of carbon dioxide and other environmental stresses have been achieved. However, the efficiency of ALE in microalgae needs to be improved, and there are few studies on the mining of synthetic biological elements based on carbon sequestration, photosynthesis and biosynthesis of active components. In order to overcome the above problems, it is urgent to change the strategy of ALE in microalgae, combined with the application of high-throughput ALE device to shorten the evolution time; Based on the existing evolved strains, the elements of tolerance genes, photosynthesis and biosynthesis of active components were deeply excavated to lay a foundation for microalgae genetic transformation; Learn from the existing experience of ALE in microorganisms, deeply understand the dynamic process of ALE in microalgae, and explore the basic law of ALE. Finally, the possible ways of laboratory adaptive evolution to meet the challenge of microalgae carbon neutrality were prospected.

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