Improving itaconic acid production through genetic engineering of an industrial Aspergillus terreus strain

Abstract

BackgroundItaconic acid, which has been declared to be one of the most promising and flexible building blocks, is currently used as monomer or co-monomer in the polymer industry, and produced commercially by Aspergillus terreus. However, the production level of itaconic acid hasn’t been improved in the past 40 years, and mutagenesis is still the main strategy to improve itaconate productivity. The genetic engineering approach hasn’t been applied in industrial A. terreus strains to increase itaconic acid production.ResultsIn this study, the genes closely related to itaconic acid production, including cadA, mfsA, mttA, ATEG_09969, gpdA, ATEG_01954, acoA, mt-pfkA and citA, were identified and overexpressed in an industrial A. terreus strain respectively. Overexpression of the genes cadA (cis-aconitate decarboxylase) and mfsA (Major Facilitator Superfamily Transporter) enhanced the itaconate production level by 9.4% and 5.1% in shake flasks respectively. Overexpression of other genes showed varied effects on itaconate production. The titers of other organic acids were affected by the introduced genes to different extent.ConclusionsItaconic acid production could be improved through genetic engineering of the industrially used A. terreus strain. We have identified some important genes such as cadA and mfsA, whose overexpression led to the increased itaconate productivity, and successfully developed a strategy to establish a highly efficient microbial cell factory for itaconate protuction. Our results will provide a guide for further enhancement of the itaconic acid production level through genetic engineering in future.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-014-0119-y) contains supplementary material, which is available to authorized users.

Emerging biotechnologies for production of itaconic acid and its applications as a platform chemical

“…By insertion of the modified A. niger pfKA genes into A. terreus strain, specific productivities and final yields of IA were increased in comparison to the parent strain. Huang et al [33] overexpressed cadA and mfsA (major facilitator superfamily transporter) genes in A. terreus and obtained enhanced IA production level by 9.4 and 5.1% in shake flasks, respectively, in comparison to wild type. Geiser et al [23] reported that overexpression of a pathway-specific transcription factor (Ria1) or a mitochondrial tricarboxylic acid transporter (Mtt1) in U. maydis resulted in a 2-fold increase in IA yield.…”

“…cis-Aconitate is transported back into the cytosol with the help of mitochondrial tricarboxylic acid transporter and serves as a precursor for IA production by decarboxylation by the action of cis-aconitic acid decarboxylase (CAD, EC 4.1.16, Fig. 1) [10,33,34,83]. Bentley and Thiessen [3,4] successfully decarboxylated cis-aconitic acid into IA using crude CAD.…”

Identification of an itaconic acid degrading pathway in itaconic acid producing Aspergillus terreus

“…Although the most significant progress in improving itaconic acid production is made by classical process optimization techniques until now (Hevekerl et al 2014), the construction of mutant strains by genetic engineering is also promising for improving the itaconic acid production. For example, overexpression of CAD in A. terreus LYT10 enhanced the itaconic acid production level by nearly 10 % in shake flasks, and the production stage was shortened by around 4 h at the pilot scale (35 m 3 fermentor) (Huang et al 2014b). We do believe that the combination of classical process optimization and genetic engineering will make greater progress in improving itaconic acid production.…”

“…In an effect to improve the application potential of itaconic acid, a great deal of research related to itaconic acid biosynthesis (Bonnarme et al 1995;Jaklitsch et al 1991;Li et al 2011) and its regulation mechanism (Huang et al 2014b;Lin et al 2004;Reddy and Singh 2002;Tevz et al 2010) have been carried out to improve the production efficiency of itaconic acid. In addition to enhancing the biosynthesis pathway, disrupting or weakening the degradation pathway by metabolic engineering is also an effective strategy to promote the accumulation of target products.…”

Itaconic acid production from glycerol using Escherichia coli harboring a random synonymous codon‐substituted 5′‐coding region variant of the cadA gene

“…Until now, various studies, including those employing optimization of culture conditions and the improvement and development of hosts, have tried to improve production yield. Despite these efforts, there has been no improvement in the maximum productivity of IA (86.2 g/L) in the past 40 years (Huang et al, 2014b).…”