Converting greenhouse gas methane to microbial Protein: The state-of-the-art and future prospects

The food crisis is one of the critical global challenges. Microbial protein (MP) production from methane is a promising solution, which offers a sustainable pathway to meet the growing global demand for dietary protein and mitigate greenhouse gas emissions. In this review, we provide a comprehensive overview of the methane-based MP production and highlight the technology advancements and challenges. Currently, there are three major challenges of methane-based MP production: i) improving carbon utilization efficiency, ii) enhancing protein quality, iii) and reducing nutrient input costs. To address these technical challenges, we discuss and compare various strategies. To achieve efficient carbon utilization, a co-culture system can be adopted by combining methanotrophs and autotrophic microorganisms (e.g., hydrogen-oxidizing bacteria), which also enables to improve protein quality by broadening the amino acid profile. Additionally, innovations in bioreactor design, such as hollow fiber membranes and two-phase partitioning systems, enhance gas transfer efficiency, while electrochemical ammonium extraction offers a promising method for nutrient recovery from anaerobic digestate. Furthermore, genetic engineering holds great promise in optimizing methanotrophic metabolism to advance methane-based MP production.