Metabolic Engineering of Trichoderma reesei for L-Malic Acid Production

L-Malic acid has various applications in the chemical and food industries. The filamentous fungus Trichoderma reesei is known to be an efficient enzyme producer. Here, through metabolic engineering, T. reesei was constructed for the first time as an excellent cell factory for L-malic acid production. The heterologous overexpression of genes encoding the C4-dicarboxylate transporter from Aspergillus oryzae and Schizosaccharomyces pombe initiated L-malic acid production. The overexpression of pyruvate carboxylase from A. oryzae in the reductive tricarboxylic acid pathway further increased both the titer and yield of L-malic acid, resulting in the highest titer reported in a shake-flask culture. Furthermore, the deletion of malate thiokinase blocked L-malic acid degradation. Finally, the engineered T. reesei strain produced 220.5 g/L of L-malic acid in a 5 L fed-batch culture (productivity of 1.15 g/L/h). A T. reesei cell factory was created for the efficient production of L-malic acid.

Automated summary

By using metabolic engineering, the filamentous fungus Trichoderma reesei was successfully transformed into an efficient cell factory for producing L-malic acid. The overexpression of heterologous genes and the manipulation of the reductive tricarboxylic acid pathway resulted in increased production and yield of L-malic acid. The engineered T. reesei strain achieved the highest reported titer of 220.5 g/L in a 5 L fed-batch culture.