Sustainable protein production from methane-oxidizing bacteria: environmental and economic comparison with conventional protein sources

Abstract Conventional protein sources are increasingly challenged due to their substantial environmental impacts, including land degradation, deforestation, and marine ecosystem disruption. This study presented a comparative life cycle assessment (LCA) and techno-economic evaluation of microbial protein produced from methane-oxidizing bacteria (MOB), comparing with traditional protein sources. Three systems were assessed, including System 1 (soybean meal), System 2 (fish meal), and System 3 (MOB-derived microbial protein). System 1 and System 2 exhibited pronounced environmental negative effects, with soybean meal dominated by land use and agricultural inputs, while fish meal was characterized by substantial fuel demand and emission-related burdens during fishing and processing. In contrast, microbial protein exhibited the lowest overall environmental burden, reducing ecosystem damage by 88% compared to soybean meal and reducing human health impacts by 41% relative to fish meal. Although microbial protein production is energy-intensive, it required minimal land and water use, and avoided deforestation and marine resource depletion. Furthermore, three methane purification techniques were evaluated within System 3 by sensitivity analysis, including Ammonia Washing, Membrane Technique, and Pressure Swing Adsorption (PSA). PSA emerged as the favorable method, offering the lowest environmental impact and the highest operational robustness, reducing resource depletion by over 140% compared to Membrane Technique. From an economic perspective, in the three systems, MOB-derived microbial protein achieved the highest net present value ($3.40 million) and return on investment (51%). These findings underscored the environmental and economic viability of microbial protein as a next-generation protein source, particularly for regions facing constraints in arable land or marine ecosystems. The study provided critical insights to support the industrial-scale application of methane-based microbial protein in sustainable food and feed systems. Graphical Abstract