• DOI:10.1093/femsle/fnv079
• Corpus ID: 22622395

Construction of a Bacillus amyloliquefaciens strain for high purity levan production.

@article{Feng2015ConstructionOA,
  title={Construction of a Bacillus amyloliquefaciens strain for high purity levan production.},
  author={Jun Feng and Yanyan Gu and Lifang Han and Kexin Bi and Yufen Quan and Chao Yang and Wei Zhang and Mingfeng Cao and Shufang Wang and Weixia Gao and Yang Sun and Cunjiang Song},
  journal={FEMS microbiology letters},
  year={2015},
  volume={362 11}
}

• Jun Feng, Yanyan Gu, +9 authors Cunjiang Song
• Published 1 June 2015
• Biology
• FEMS microbiology letters

Bacillus amyloliquefaciens NK-1 has the potential to produce levan and poly-gamma-glutamic acid (γ-PGA) simultaneously. However, it is not possible to purify each single product from the same strain because the extraction process is identical. We deleted the pgs cluster (for γ-PGA synthesis) from the NK-1 strain and constructed a γ-PGA-deficient NK-ΔLP strain. Nuclear magnetic results showed that the NK-ΔLP strain could produce high purity levan product. However, its levan titer was only 1.96 g L(-1) in the basal medium. Single-factor experimental and response surface methodology was used to optimize the culture condition, leading to levan titer of 13.9 and 22.6 g L(-1) in flask culture and in a 5-L bioreactor, respectively. The levan purity can reach to 92.7% after 48 h cultivation. Furthermore, the relationship between levanase (LevB) and levan molecular weight was studied. The results showed that LevB resulted in the production of low molecular weight levan and its expression level determined the ratio of high and low molecular weight levan. We also deleted the sac cluster (for levan synthesis) from the NK-1 strain and constructed a levan-deficient NK-L strain. The NK-L strain exhibited increased purity of γ-PGA product from 79.5 to 91.2%.