Itaconic acid production from corn stover hydrolysates for a newly isolated Aspergillus terreus through adaptive evolution.

Abstract

Itaconic acid can be produced using lignocellulosic biomass; however, the inhibitors from pretreatment process of biorefinery are toxic to the fermenting strains. Here, with 35.70 ± 0.69 g/L (0.19 ± 0.05 g/L·h and 73.84 ± 0.01%) itaconic acid from shake flask fermentation of synthetic medium (SM), a newly isolated Aspergillus terreus just produced 1.01 ± 0.01 g/L itaconic acid from corn stover hydrolysates (CSH) for the serious block of aldehyde inhibitors and acetic acid. Convincingly, 25.34 ± 3.94 g/L (0.13 ± 0.02 g/L·h and 37.92 ± 3.89%) itaconic acid was achieved from the detoxified CSH (with residual 0.49 g/L acetic acid) using 4.0% activated charcoal. 21.64 ± 2.42 g/L (0.05 ± 0.01 g/L·h and 26.96 ± 7.81%) itaconic acid was further achieved from CSH for the adapted A. terreus with better degradation ability of furanic aldehydes and phenolic aldehydes. Furthermore, the 108 mutation sites of nine genes from adaptive laboratory evolution (ALE) for A. terreus were further uncovered through single nucleotide polymorphisms (SNPs) analysis, and thus would be responsible for the improved fermentability of itaconic acid from CSH. The current work broke the bottlenecks in itaconic acid fermentation directly from CSH through improving A. terreus using directed evolution technique, and thus would provide a strain biocatalyst A. terreus and establish the alternative strategy to efficiently produce itaconic acid using corn stover.