A novel nutritional induction strategy flexibly switching the biosynthesis of food-like products from methane by a methanotrophic bacterium

From the perspective of a circular economy, the bioconversion of methane into valuable protein and carbohydrates can provide alternative food resources, while reducing greenhouse gas emissions. In this study, a nutritional induction strategy for artificial biomanufacturing by an industrial-promising methanotrophic bacterium was proposed for the first time. Three different scenarios of methanotrophic cultivations were carried out by manipulating the availability of oxygen and nitrogen during fermentation to investigate the flexible and efficient biosynthesis of cell proteins, glycogen, and extracellular polysaccharides (EPS). The highest titer of glycogen (5.21 g L⁻¹) and EPS (15.81 g L⁻¹) was observed in scenario I and scenario II, respectively. However, the maximum cell protein productivity (640.05 mg L⁻¹ h⁻¹) was achieved in scenario III with nutrimental balance, resulting in a 2.1-fold enhancement compared to scenario I under nutrient depletion. Further transcriptomic analysis revealed the nutritional induction mechanism, with central carbon and nitrogen metabolisms being boosted with sufficient key nutrients in scenario III, leading to the significant up-regulation of related genes towards protein synthesis. Additionally, a preliminary economic and environmental assessment highlighted the potential benefits of methane-based biomanufacturing in reducing production expenses and greenhouse gas emissions, which may help drive innovation and the development of sustainable and environmentally friendly products.