This study aimed to investigate the effects of exogenous regulation of cofactor folate on C.glutamicum SYPS-062 growth and L-serine accumulation by adding the precursor(p-aminobenzoate,PABA) or inhibitor(methotrexate) of folate biosynthesis to the medium,respectively.The results indicated that the biomass enhanced and reached a maximum value of 7.8 ± 0.24 g /L,while the concentration of L-serine sharply declined as the concentration of PABA was increased from 0 to 0.4 μg /mL.In contrast,the biomass of C.glutamicum SYPS-062 decreased while the L-serine yield to biomass increased with the increase in the concentration of methotrexate from 0 to 100 μg /mL.Metabolic flux analysis showed that folate metabolism played an important role in cell growth and L-serine accumulation of C.glutamicum SYPS-062.