Growth dynamic curve and gene expression analysis for optimized culture medium of Mycoplasma hyopneumoniae CJ strain

Mycoplasma hyopneumoniae is a significant pathogen in swine respiratory diseases, but its slow growth and nutrient dependency limit industrial production efficiency. This study developed optimized culture formulations (CL6 and GD-240) by integrating key components to enhance M. hyopneumoniae biomass and metabolic efficiency. A dynamic monitoring system combining the Logistic growth model with flow cytometry was established to quantify kinetic parameters, overcoming limitations of traditional Color Change Unit (CCU) assays. Results showed that GD-240 increased maximum biomass by 17.5%, extended the exponential phase by 2.53 hours, and elevated v _max by 14.77%. Gene expression analysis revealed metabolic reprogramming, with upregulation of pentose phosphate pathway (PPP) genes supporting nucleotide synthesis, and suppression of glycolytic flux. Virulence genes were downregulated, indicating a trade-off between growth prioritization and virulence traits. The GD-240 formulation enables high-yield M. hyopneumoniae cultivation while maintaining functional stability, providing a foundation for vaccine antigen production.