Poly (β-L-malic acid) (PMLA) is a biopolymer with excellent biocompatibility and degradability, and improving its microbial synthesis efficiency is crucial for industrial applications.This study aimed to investigate the promotional effect of acetate salts on PMLA synthesis by Aureobasidium melanogenum and elucidate the underlying mechanism.The optimal concentration of potassium acetate was determined via single-factor optimization and further validated in a 5 L fermenter.Metabolomic and transcriptomic analyses were performed to examine changes in intracellular metabolites and gene expression, respectively, while the activity of isocitrate lyase (ICL), a key enzyme in the metabolic pathway, was measured.Results showed that the addition of 3 g/L potassium acetate significantly increased the PMLA yield to 59.98 g/L, which represented a 27.85% increase compared to the control group and a 36.67% improvement in yield per unit biomass.Metabolomic analysis revealed enhanced accumulation of intermediate metabolites such as pyruvate and glyoxylate.Transcriptomic analysis indicated upregulation of genes associated with glycolysis and the glyoxylate cycle (e.g., sgA1, glpK, and gde).Additionally, the activity of the ICL enzyme activity in the experimental group was 3.23 times higher than that of the control group.This study demonstrated that potassium acetate promoted PMLA synthesis by enhancing the capacities of glycolytic and the glyoxylate cycle, thereby providing a novel strategy for the efficient fermentative production of PMLA.
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