How to enhance carbon capture by evolution of microalgal photosynthesis?

Abstract

Anthropogenic carbon dioxide (CO2) emissions are one of the most serious global risks humanity is facing in the 21st century. Biodegradation of CO2 has obtained increasing attention as an environment-friendly technology. Microalgae are receiving worldwide attention in this regard due to their rapid growth rate, strong adaptability to extreme environments, and low production cost. Additionally, microalgae are very important CO2 fixers in the ecological environment, fixing carbon as biomass through photosynthesis. Although many review studies have focused on carbon capture, utilization and storage (CCUS) using microalgae, the comprehensive review on summarizing the updated strategies to further enhance carbon capture using microalgae is still lacking. Therefore, this review initially introduces the various carbon capture strategies, especially the biological route. The efficiency of CO2 capture using microalgae can vary according to the state of microalgal species, physiology, and environmental conditions, such as CO2 concentrations, pH, light intensity, and dissolved oxygen. Then, photosynthesis and related carbon-fixation mechanisms in microalgae are systematically discussed. More critically, the recent developments in trends and strategies to further enhance microalgal CO2 fixation (such as mutagenesis, genetic engineering, and intervention through nanomaterials) are comprehensively discussed and summarized. Among them, nanomaterials could considerably enhance the rates of relative electron transport in photosynthetic system II as well as reactive oxygen species levels in microalgae, thus improving the general photosynthesis towards carotenoids. Furthermore, current challenges are highlighted, and future perspectives are provided. The study could help guide academia and industry in redirecting their efforts to increase the performance of microalgal CO2 fixation.