Efficient itaconic acid production by Aspergillus terreus –Overcoming the strong inhibitory effect of manganese

Authors: Saha, Badal; Kennedy, Gregory - Greg

Submitted to: Biotechnology Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2019
Publication Date: 11/4/2019
Citation: Saha, B.C., Kennedy, G.J. 2019. Efficient itaconic acid production by Aspergillus terreus –Overcoming the strong inhibitory effect of Manganese. Biotechnology Progress. 36(2):e2939. https://doi.org/10.1002/btpr.2939.
DOI: https://doi.org/10.1002/btpr.2939

Interpretive Summary: Itaconic acid is a building block platform chemical which is produced industrially from glucose by fermentation with a fungus. Biomass has the potential to serve as low cost source of sugar for itaconic acid production. However, the fungus could not produce itaconic acid from hydrolyzed biomass. Among other factors, one metal ion was found to severely inhibit the itaconic acid production. In this work, a novel medium was developed in which the fungus was able to produce itaconic acid efficiently overcoming the strong inhibitory effect of the metal. The results will be very useful in developing process technology for itaconic acid production by the fungus in the presence of the metal.

Technical Abstract: Itaconic acid (IA), a building block platform chemical, is produced industrially by Aspergillus terreus utilizing glucose. Expanding the use of IA requires lowering its production cost. Lignocellulosic biomass has the potential to serve as a low cost source of sugars for IA production. However, the fungus could not produce IA from dilute acid pretreated and enzymatically saccharified wheat straw hydrolyzate even at 100 fold dilution. Furfural, hydroxymethyl furfural and acetic acid were inhibitory, as is typical, but Mn2+ was particularly problematic for IA production. It was present in the hydrolyzate at a level that was 230 times over the inhibitory limit (50 ppb). Recently, it was found that PO43- limitation decreased the inhibitory effect of Mn2+ on IA production. In the present study, a novel medium was developed for production of IA by varying PO43-, Fe3+ and Cu2+ concentrations using response surface methodology which alleviated the strong inhibitory effect of Mn2+. The fungus was able to produce IA very well in the presence of Mn2+ up to 100 ppm in the newly developed medium. This medium will be extremely useful for IA production in the presence of Mn2+. This is the first report on the development of Mn2+ tolerant medium for IA production by A. terreus.