title: Regulating Pyruvate Carboxylase in the Living Culture of Aspergillus Terreus Nrrl 1960 by L-Aspartate for Enhanced Itaconic Acid Production.
abstract: Aspergillus terreus was reported as the promising fungal strain for itaconic acid; however, the commercial production suffers from the low yield. Low production yield was claimed as the result of completing the tricarboxylic acid (TCA) cycle towards biomass synthesis while under limiting phosphate and nitrogen; TCA cycle was somewhat shunted and consequently, the metabolite fluxes move towards itaconic acid production route. By regulating enzymes in TCA cycle, it is believed that itaconic acid production can be improved. One of the key responsible enzymes involved in itaconic acid production was triggered in this study. Pyruvate carboxylase was allosterically inhibited by L-aspartate. The presence of 10 mM L-aspartate in the production medium directly repressed PC expression in the living A. terreus while the limited malate flux regulated the malate/citrate antiporters resulting in the increasing cis-aconitate decarboxylase activity to simultaneously convert cis-aconitate, citrate isomer, into itaconic acid. The transport of cis-aconitate via the antiporters induced citrate synthase and 6-phosphofructo-1-kinase activities in response to balance the fluxes of TCA intermediates. Successively, itaconic acid production yield and final concentration could be improved by 8.33 and 60.32 %, respectively, compared to those obtained from the control fermentation with the shortened lag time to produce itaconic acid during the production phase.
authors.affiliation: Biotechnology Program, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Pajareeya
authors.initials: P
authors.lastname: Songserm
authors.affiliation: Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Sitanan
authors.initials: S
authors.lastname: Thitiprasert
authors.affiliation: Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Vasana
authors.initials: V
authors.lastname: Tolieng
authors.affiliation: Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Jiraporn
authors.initials: J
authors.lastname: Piluk
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Somboon
authors.initials: S
authors.lastname: Tanasupawat
authors.affiliation: Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Sutthichai
authors.initials: S
authors.lastname: Assabumrungrat
authors.affiliation: William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH, 43210, USA.
authors.forename: Shang-Tian
authors.initials: ST
authors.lastname: Yang
authors.affiliation: Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Aphichart
authors.initials: A
authors.lastname: Karnchanatat
authors.affiliation: Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, 10330, Thailand. Nuttha.T@chula.ac.th.
authors.forename: Nuttha
authors.initials: N
authors.lastname: Thongchul
mesh_terms: D000494:Allosteric Regulation / Q000187:drug effects; D001224:Aspartic Acid / Q000494:pharmacology*; D001234:Aspergillus niger / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D001709:Biotechnology / Q000379:methods*; D003470:Culture Media / Q000737:chemistry; D046508:Culture Techniques; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005285:Fermentation / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D011766:Pyruvate Carboxylase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism*
chemical_list: D003470:Culture Media; D004791:Enzyme Inhibitors; D013386:Succinates; D001224:Aspartic Acid; D011766:Pyruvate Carboxylase; D005947:Glucose; C005229:itaconic acid
keywords: 6-phosphofructo-1-kinase; Allosteric inhibition; Aspergillus terreus; Cis-aconitate decarboxylase; Fermentation; Itaconic acid; L-aspartate; Pyruvate carboxylase