Applied Microbiology and Biotechnology

, Volume 98, Issue 14, pp 6397–6407 | Cite as

Functions of poly-gamma-glutamic acid (γ-PGA) degradation genes in γ-PGA synthesis and cell morphology maintenance

  • Jun Feng
  • Weixia Gao
  • Yanyan Gu
  • Wei Zhang
  • Mingfeng Cao
  • Cunjiang SongEmail author
  • Peng Zhang
  • Min Sun
  • Chao Yang
  • Shufang WangEmail author
Applied genetics and molecular biotechnology


Poly-γ-glutamic acid (γ-PGA) is an important biopolymer with greatly potential in industrial and medical applications. In the present study, we constructed a metabolically engineered glutamate-independent Bacillus amyloliquefaciens LL3 strain with considerable γ-PGA production, which was carried out by single, double, and triple markerless deletions of three degradation genes pgdS, ggt, and cwlO. The highest γ-PGA production (7.12 g/L) was obtained from the pgdS and cwlO double-deletion strain NK-pc, which was 93 % higher than that of wild-type LL3 strain (3.69 g/L). The triple-gene-deletion strain NK-pgc showed a 28 % decrease in γ-PGA production, leading to a yield of 2.69 g/L. Furthermore, the cell morphologies of the mutant strains were also characterized. The cell length of cwlO deletion strains NK-c and NK-pc was shorter than that of the wild-type strain, while the ggt deletion strains NK-g, NK-pg, NK-gc, and NK-pgc showed longer cell lengths. This is the first report concerning the markerless deletion of γ-PGA degradation genes to improve γ-PGA production in a glutamate-independent strain and the first observation that γ-glutamyltranspeptidase (encoded by ggt) could be involved in the inhibition of cell elongation.


Poly-γ-glutamic acid γ-PGA-degrading enzymes Glutamate-independent synthesis Gene markerless deletion 



This work was supported by the National key Basic Research Program of China (“973”-Program) 2012CB725204, National High Technology Research and Development Program of China (“863”-Program) 2012AA021505, Natural Science Foundation of China Grant Nos. 31070039, 31170030, 31300032, and 51073081, Project of Tianjin, China (13JCZDJC27800, 13JCYBJC24900). The Project of Tianjin, China (13JCQNJC09700).

Supplementary material

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Jun Feng
    • 1
    • 2
  • Weixia Gao
    • 1
  • Yanyan Gu
    • 1
  • Wei Zhang
    • 1
  • Mingfeng Cao
    • 3
  • Cunjiang Song
    • 1
    Email author
  • Peng Zhang
    • 1
  • Min Sun
    • 1
  • Chao Yang
    • 1
  • Shufang Wang
    • 2
    Email author
  1. 1.Key Laboratory of Molecular Microbiology and Technology of Ministry of EducationNankai UniversityTianjinChina
  2. 2.State Key Laboratory of Medicinal Chemical BiologyNankai UniversityTianjinChina
  3. 3.Department of Chemical and Biological EngineeringIowa State UniversityAmesUSA

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