Presentation Information
[P04-470]Secretory production of itaconic acid by the white koji fungus Aspergillus luchuensis mut. kawachii
○Atsushi Nishitani1, Kentaro Hiramatsu2, Chihiro Kadooka3, Yumiko Yoshizaki2,4, Kazunori Takamine2,4, Masatoshi Goto5, Hisanori Tamaki2,4, Taiki Futagami2,4 (1. Cent. Adv. Sci. Res. Promot., Kagoshima University (Japan), 2. United Grad. Sch. Agric. Sci., Kagoshima Univ. (Japan), 3. Fac. Biotechnol. Life Sci., Sojo Univ. (Japan), 4. Fac. Agric., Kagoshima Univ. (Japan), 5. Fac. Agric., Saga Univ. (Japan))
Keywords:
White koji fungus,Aspergillus luchuensis mut. kawachii,Citric acid,Itaconic acid,Transporter
Itaconic acid is a dicarboxylic acid produced by the filamentous fungus Aspergillus terreus and is widely used in the manufacture of unsaturated polyester resins, synthetic fibers, and superabsorbent polymers. Owing to its versatile industrial applications, the global demand for itaconic acid has been increasing. In A. terreus, itaconic acid is biosynthesized from citric acid via cis-aconitic acid. Citric acid is converted to cis-aconitic acid by mitochondrial aconitase, transported to the cytosol via the mitochondrial transporter MttA, and subsequently converted to itaconic acid by cytosolic cis-aconitate decarboxylase (CadA). The produced itaconic acid is then secreted extracellularly via the plasma membrane transporter MfsA.
In this study, we demonstrated the secretory production of itaconic acid by the white koji fungus Aspergillus luchuensis mut. kawachii, which is used in the production of shochu, a traditional Japanese distilled spirit. A. kawachii secretes large amounts of citric acid, which can potentially serve as a precursor for itaconic acid biosynthesis. Previous studies have shown that citric acid is secreted via the plasma membrane transporter CexA in the white koji fungus, and that disruption of cexA markedly decreases extracellular citric acid accumulation. Therefore, we constructed a ΔcexA strain overexpressing cadA under the control of the tefApromoter and mttA under the control of the gpdA promoter, and analyzed organic acid concentrations in the culture supernatant by HPLC. The ΔcexA PtefA-cadA PgpdA-mttA strain produced 14.4 g/L of itaconic acid in the culture supernatant (from 100 g/L glucose).
In addition, we investigated the effects of overexpressing mfsA from A. terreus and the putative plasma membrane-localized dicarboxylic acid transporter genes chlH and chlK encoded in the genome of A. kawachii, under the control of the tefA promoter. The mfsA, chlH, and chlK overexpression strains produced 11.1, 19.5, and 7.2 g/L of itaconic acid in the culture supernatant, respectively. Thus, overexpression of mfsA did not improve itaconic acid secretion, whereas overexpression of chlH enhanced the secretory production of itaconic acid in A. kawachii. These findings contribute to the development of fermentation-based production platforms for itaconic acid using the white koji fungus.
In this study, we demonstrated the secretory production of itaconic acid by the white koji fungus Aspergillus luchuensis mut. kawachii, which is used in the production of shochu, a traditional Japanese distilled spirit. A. kawachii secretes large amounts of citric acid, which can potentially serve as a precursor for itaconic acid biosynthesis. Previous studies have shown that citric acid is secreted via the plasma membrane transporter CexA in the white koji fungus, and that disruption of cexA markedly decreases extracellular citric acid accumulation. Therefore, we constructed a ΔcexA strain overexpressing cadA under the control of the tefApromoter and mttA under the control of the gpdA promoter, and analyzed organic acid concentrations in the culture supernatant by HPLC. The ΔcexA PtefA-cadA PgpdA-mttA strain produced 14.4 g/L of itaconic acid in the culture supernatant (from 100 g/L glucose).
In addition, we investigated the effects of overexpressing mfsA from A. terreus and the putative plasma membrane-localized dicarboxylic acid transporter genes chlH and chlK encoded in the genome of A. kawachii, under the control of the tefA promoter. The mfsA, chlH, and chlK overexpression strains produced 11.1, 19.5, and 7.2 g/L of itaconic acid in the culture supernatant, respectively. Thus, overexpression of mfsA did not improve itaconic acid secretion, whereas overexpression of chlH enhanced the secretory production of itaconic acid in A. kawachii. These findings contribute to the development of fermentation-based production platforms for itaconic acid using the white koji fungus.
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