Itaconic acid production by Aspergillus terreus from glucose up to pilot scale and from corn stover and wheat straw hydrolysates using new manganese tolerant medium

Authors: Saha, Badal; Kennedy, Gregory - Greg; Bowman, Michael; Qureshi, Nasib; Nichols, Nancy

Submitted to: Biocatalysis and Agricultural Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2022
Publication Date: 7/6/2022
Citation: Saha, B.C., Kennedy, G.J., Bowman, M.J., Qureshi, N., Nichols, N.N. 2022. Itaconic acid production by Aspergillus terreus from glucose up to pilot scale and from corn stover and wheat straw hydrolysates using new manganese tolerant medium. Biocatalysis and Agricultural Biotechnology. 43. Article 102418. https://doi.org/10.1016/j.bcab.2022.102418.
DOI: https://doi.org/10.1016/j.bcab.2022.102418

Interpretive Summary: Itaconic acid is a building block platform chemical which is produced industrially from sugar by fermentation with a fungus. Agricultural residues have the potential to serve as a low cost source of sugar for itaconic acid production. However, the fungus could not produce itaconic acid from hydrolyzed corn stover or wheat straw. Among other factors, one metal ion was found to severely inhibit the itaconic acid production. A novel method was developed in which the fungus was able to produce itaconic acid efficiently overcoming the strong inhibitory effect of the metal. In this paper, the effectiveness of this medium for itaconic acid production was demonstrated at pilot scale using a stainless steel fermenter. This is significant because steel leaches metal ions. The productions of itaconic acid from corn stover cellulosic hydrolysate and mitigated wheat straw hydrolysate using the metal tolerant medium were also demonstrated. The results will be very useful for corn wet millers looking for additional outlets for their glucose syrups and eventually for farmers looking to develop markets for crop residues.

Technical Abstract: Itaconic acid (IA), a building block platform chemical, is produced industrially from glucose by Aspergillus terreus. Lignocellulosic biomass has the potential to serve as a low cost source of sugars for IA production. However, A. terreus does not produce IA from dilute acid pretreated and enzymatically saccharified wheat straw hydrolysate even at 100 fold dilution. In addition to organic inhibitors, Mn2+ strongly inhibits IA production. Mn2+ was present in the hydrolysate at a level 230 times over the inhibitory limit (50 ppb). Recently, PO43- limitation was shown to decrease the inhibitory effect of Mn2+ on IA production and a medium was formulated in which A. terreus produced IA very efficiently in the presence of Mn2+ up to 100 ppm. Here, the effectiveness of this medium was demonstrated at pilot scale using a stainless steel bioreactor and glucose as the substrate. The productions of IA from corn stover cellulosic hydrolysate in a biorefinery concept and mitigated wheat straw hydrolysate using the Mn2+ tolerant medium were also demonstrated at laboratory scale. The fungal strain produced 74% IA from cellulosic hydrolysate and 98% IA from wheat straw hydrolysate in comparison with respective mock sugar solution. This is the first report on using Mn2+ tolerant medium to achieve IA production by A. terreus on hydrolysates.