Contributed equally to this work.
Construction of a dextran-free Leuconostoc citreum mutant by targeted disruption of the dextransucrase gene
Article first published online: 14 JUL 2014
© 2014 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 117, Issue 4, pages 1104–1112, October 2014
How to Cite
Jin, Q., Li, L., Kim, Y.J. and Han, N.S. (2014), Construction of a dextran-free Leuconostoc citreum mutant by targeted disruption of the dextransucrase gene. Journal of Applied Microbiology, 117: 1104–1112. doi: 10.1111/jam.12587
- Issue published online: 15 SEP 2014
- Article first published online: 14 JUL 2014
- Accepted manuscript online: 24 JUN 2014 05:41AM EST
- Manuscript Accepted: 20 JUN 2014
- Manuscript Revised: 18 JUN 2014
- Manuscript Received: 30 APR 2014
- National Natural Science Foundation of China. Grant Numbers: 31060212, 31260362
- Korean National Academy of Agriculture, Rural Development Administration. Grant Number: PJ008626
- Intelligent Synthetic Biology Center of Global Frontier Project, ICT & Future Planning. Grant Number: 2013M3A6A8073553
- Ministry of Science, Republic of Korea
- chromosomal gene inactivation;
- fermented foods;
- lactic acid bacteria
Leuconostoc citreum is an important lactic acid bacterium in fermented foods, but dextran production often causes undesired ropiness. To prevent this side effect, a dextran-free mutant needs to be created.
Methods and Results
Homologous recombination of the dextransucrase gene (dsrC) was conducted using a segregationally unstable plasmid, pCBM32-DSUDs. A mutant was obtained on sucrose agar medium, and a site-specific insertional inactivation in the gene was confirmed. When cultured in sucrose medium, the mutant strain produced no dextransucrase or dextran. Additionally, it showed a longer lag phase (9 h) than the wild-type strain (3 h), providing new insights into the role of dextransucrase in carbohydrate metabolism of Leuconostoc.
In this study, a dextransucrase knockout mutant was constructed. It was found that Leuc. citreum dextransucrase not only synthesizes dextran for cell protection but also provides fructose as an important carbon source for cell growth.
Significance and Impact of the Study
This knockout mutation was generated for the first time in Leuc. citreum. The dextran-free mutant has the potential to be used for various industrial purposes, including as a starter culture for production of nonviscous fermented foods and as a dextran-free host for production of recombinant proteins.