title: Calcium regulates glutamate dehydrogenase and poly-γ-glutamic acid synthesis in Bacillus natto.
abstract: OBJECTIVE
  To study the effect of Ca(2+) on glutamate dehydrogenase (GDH) and its role in poly-γ-glutamic acid (γ-PGA) synthesis in Bacillus natto HSF 1410.
  
  
  RESULTS
  When the concentration of Ca(2+) varied from 0 to 0.1 g/l in the growth medium of B. natto HSF 1410, γ-PGA production increased from 6.8 to 9.7 g/l, while GDH specific activity and NH4Cl consumption improved from 183 to 295 U/mg and from 0.65 to 0.77 g/l, respectively. GDH with α-ketoglutarate as substrate primarily used NADPH as coenzyme with a K m of 0.08 mM. GDH was responsible for the synthesis of endogenous glutamate. The specific activity of GDH remained essentially unchanged in the presence of CaCl2 (0.05-0.2 g/l) in vitro. However, the specific activity of GDH and its expression was significantly increased by CaCl2 in vivo. Therefore, the regulation of GDH and PGA synthesis by Ca(2+) is an intracellular process.
  
  
  CONCLUSIONS
  Calcium regulation may be an effective approach for producing γ-PGA on an industrial scale.
authors.affiliation: College of Food Engineering and Nutritional Science, Shaanxi Normal University, 620 West Chang'an Avenue, Chang'an, 710119, Xi'an, People's Republic of China. mengyonghong@snnu.edu.cn.
authors.forename: Yonghong
authors.identifier: http://orcid.org/0000-0001-7217-7874
authors.initials: Y
authors.lastname: Meng
authors.affiliation: College of Food Engineering and Nutritional Science, Shaanxi Normal University, 620 West Chang'an Avenue, Chang'an, 710119, Xi'an, People's Republic of China.
authors.forename: Guiru
authors.initials: G
authors.lastname: Dong
authors.affiliation: College of Food Engineering and Nutritional Science, Shaanxi Normal University, 620 West Chang'an Avenue, Chang'an, 710119, Xi'an, People's Republic of China.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhang
authors.affiliation: College of Food Engineering and Nutritional Science, Shaanxi Normal University, 620 West Chang'an Avenue, Chang'an, 710119, Xi'an, People's Republic of China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Ren
authors.affiliation: College of Food Engineering and Nutritional Science, Shaanxi Normal University, 620 West Chang'an Avenue, Chang'an, 710119, Xi'an, People's Republic of China.
authors.forename: Yuling
authors.initials: Y
authors.lastname: Qu
authors.affiliation: Institute of Enzyme Engineering, Shannxi Academy of Sciences, No.16 East Renmin Road, Lintong District, Xi'an, 710600, People's Republic of China.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Chen
mesh_terms: D001407:Bacillus / Q000201:enzymology / Q000254:growth & development*; D001426:Bacterial Proteins / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D005969:Glutamate Dehydrogenase / Q000378:metabolism*; D007218:Industrial Microbiology; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000096:biosynthesis; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D005969:Glutamate Dehydrogenase; D002118:Calcium
keywords: Bacillus natto; Calcium regulation; Endogenous glutamate; Glutamate; Glutamate dehydrogenase; NADPH; Poly-γ-glutamic acid