title: Branched chain amino acids maintain the molecular weight of poly(γ-glutamic acid) of Bacillus licheniformis ATCC 9945 during the fermentation.
abstract: Poly(γ-glutamic acid) mainly produced by Bacillus spp. is an industrially important compound due to several useful features. Among them, molecular weight is an important characteristic affecting on the physical properties such as viscosities and negative charge densities. However, it is difficult to control the molecular size of PGA since it decreases during fermentation. Previous study reported that PGA produced in the media containing different carbon sources such as glucose and glycerol showed differences in molecular weight. Therefore in this study, the effect of carbon source on the PGA molecular weight was examined; with the aim of developing a strategy to maintain the high molecular weight of PGA during fermentation. Our result showed that the weight average molecular weight (Mw) of PGA of Bacillus licheniformis ATCC 9945 cultivated in the media containing PTS-sugars were higher than the medium containing glycerol (non-PTS). The result of metabolome analysis indicated the possibility of CodY (a global regulator protein) activation in the cells cultivated in the media containing PTS-sugars. To mimic this effect, branched-chain amino acids (BCAAs), which are activators of CodY, were added to a medium containing glycerol. As the result, the Mw of PGA in the BCAAs-supplemented media were maintained and high during the early production phase compared to the non BCAAs-supplemented medium. These results indicate that BCAAs can repress the PGA molecular weight reduction during fermentation in B. licheniformis ATCC 9945.
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: hitoshi_mitsunaga@bio.eng.osaka-u.ac.jp.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Mitsunaga
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Sammelbau Biologie, Worringer Weg 1, Aachen 52074, Germany. Electronic address: Lena.Meissner@avt.rwth-aachen.de.
authors.forename: Lena
authors.initials: L
authors.lastname: Meissner
authors.affiliation: AVT - Biochemical Engineering, RWTH Aachen University, Sammelbau Biologie, Worringer Weg 1, Aachen 52074, Germany. Electronic address: Jochen.Buechs@avt.rwth-aachen.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Büchs
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: fukusaki@bio.eng.osaka-u.ac.jp.
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Fukusaki
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000378:metabolism*; D000069976:Bacillus licheniformis / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D002244:Carbon / Q000378:metabolism / Q000494:pharmacology; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D005285:Fermentation; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D005990:Glycerol / Q000378:metabolism / Q000494:pharmacology; D055442:Metabolome; D008970:Molecular Weight; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D014783:Viscosity
chemical_list: D000597:Amino Acids, Branched-Chain; D001426:Bacterial Proteins; D003470:Culture Media; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D002244:Carbon; D005947:Glucose; D005990:Glycerol
keywords: Bacillus licheniformis ATCC 9945; Catabolite control; Liquid chromatography coupled with tandem mass spectrometry; Metabolomics; Poly(γ-glutamic acid)