A multi-omics study on the metabolic reprogramming of a chlorophyll-deficient, high-protein Auxenochlorella pyrenoidosa mutant (CX41) generated by atmospheric and room temperature plasma (ARTP) mutagenesis.

This project aims to elucidate the molecular mechanism underlying the stable golden-yellow phenotype and enhanced protein accumulation in an Auxenochlorella pyrenoidosa mutant (CX41) generated by ARTP mutagenesis. Through comparative analysis between the wild-type (FACHB-9) and mutant strains under dark heterotrophic fermentation, we integrate phenotypic data (growth, pigment, and biochemical composition), extensive targeted metabolomics (focused on carotenoids), untargeted metabolomics, and transcriptome sequencing (RNA-Seq). Our findings reveal a hierarchical regulatory cascade: (1) Dysregulation of tetrapyrrole metabolism, leading to chlorophyll synthesis blockage and protoporphyrin IX depletion; (2) Massive downregulation of the photoprotective gene PSBS and collapse of the xanthophyll cycle, resulting in chronic plastid-derived oxidative stress; (3) Oxidative stress-driven global metabolic reprogramming, characterized by the downregulation of glycogen and lipid synthesis pathways, and redirection of carbon and nitrogen flux toward amino acid and protein biosynthesis, particularly proline and arginine. This study provides comprehensive omics data to understand how ARTP mutagenesis creates a high-protein, chlorophyll-free industrial microalga and offers insights into metabolic engineering for sustainable microbial protein production.