Lignin degradation as a crucial factor in consolidated bioprocessing for malic acid production by Myceliophthora thermophila

This study investigates the potential of CBP technique for the efficient conversion of lignocellulosic biomass into malic acid using the thermophilic fungus Myceliophthora thermophila. Transcriptomic analysis and genetic studies indicated that efficient degradation of lignin is crucial for improving the overall efficiency of CBP, as it facilitates access to cellulose and hemicellulose while enabling the utilization of lignin-derived compounds.

The assay of lignin degradation products revealed that M. thermophila can channel main lignin-derived components into the central metabolic pathway for malic acid production. The combined enhancement of lignin degradation capabilities and optimization of the cellodextrin utilization pathway in M. thermophila resulted in 52.9% increase in malic acid production, from 36.3 g/L to 55.5 g/L directly from raw corncob. In a bioreactor, malic acid titer reached 151.2 g/L by one-step bioconversion of plant biomass, with the productivity and yield of 1.09 g/L/h and 0.55 g/g raw corncob.