Atmospheric and room temperature plasma mutagenesis of Graesiella emersonii for enhanced protein production using methanol as novel carbon source.

Methanol presents a promising alternative carbon source for microalgal cultivation, yet its effective utilization remains challenging. This study generated methanol-tolerant Graesiella emersonii strain through Atmospheric and Room Temperature Plasma mutagenesis. The selected mutant exhibited 60% higher growth rate than wild-type in methanol-supplemented medium. Comparative analysis revealed enhanced photosynthetic efficiency, nitrogen assimilation, and carbon fixation in the mutant strain, enabling 27.1% greater methanol consumption. Biochemical profiling demonstrated simultaneous enhancement of carbohydrate (40%) and protein (40%) accumulation with improved essential amino acid composition. Fatty acid analysis showed increased membrane unsaturation as an adaptive response to methanol stress. Additionally, the mutant strain accumulated higher levels of valuable carotenoids, particularly astaxanthin. These findings establish a foundation for methanol-based microalgal biorefineries producing high-quality protein alongside valuable pigments, offering both economic and environmental benefits through industrial methanol utilization.