title: Hyperproduction of γ-glutamyl transpeptidase from Bacillus licheniformis ER15 in the presence of high salt concentration.
abstract: BACKGROUND
  Microbial γ-glutamyl transpeptidases (GGTs) have been exploited in biotechnological, pharmaceutical, and food sectors for the synthesis of various γ-glutamyl compounds. But, till date, no bacterial GGTs are commercially available in the market because of lower levels of production from various sources. In the current study, production of GGT from Bacillus licheniformis ER15 was investigated to achieve high GGT titers.
  
  
  RESULTS
  Hyperproduction of GGT from B. licheniformis ER15 was achieved with 6.4-fold enhancement (7921.2 ± 198.7 U/L) by optimization of culture medium following one-variable-at-a-time strategy and statistical approaches. Medium consisting of Na2HPO4: 0.32% (w/v); KH2PO4: 0.15% (w/v); starch: 0.1% (w/v); soybean meal: 0.5% (w/v); NaCl: 4.0% (w/v), and MgCl2: 5 mM was found to be optimal for maximum GGT titers. Maximum GGT titers were obtained, in the optimized medium at 37°C and 200 rpm, after 40 h. It was noteworthy that GGT production was a linear function of sodium chloride concentration, as observed during response surface methodology. While investigating the role of NaCl on GGT production, it was found that NaCl drastically decreased subtilisin concentration and indirectly increasing GGT recovery.
  
  
  CONCLUSIONS
  B. licheniformis ER15 is proved to be a potential candidate for large-scale production of GGT enzyme and its commercialization.
authors.affiliation: a Department of Microbiology , University of Delhi , South Campus , New Delhi , India.
authors.forename: Shruti
authors.initials: S
authors.lastname: Bindal
authors.affiliation: a Department of Microbiology , University of Delhi , South Campus , New Delhi , India.
authors.forename: Rani
authors.initials: R
authors.lastname: Gupta
mesh_terms: D000069976:Bacillus licheniformis / Q000201:enzymology*; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D012965:Sodium Chloride / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D005723:gamma-Glutamyltransferase / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D012965:Sodium Chloride; D005723:gamma-Glutamyltransferase
keywords: Bacillus licheniformis; production; response surface methodology; sodium chloride; subtilisin; γ-glutamyl transpeptidases