Overexpression of mltA in Edwardsiella tarda reduces resistance to antibiotics and enhances lethality in zebra fish
Article first published online: 20 APR 2012
© 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 112, Issue 6, pages 1075–1085, June 2012
How to Cite
Liu, W., Dong, N. and Zhang, X.-H. (2012), Overexpression of mltA in Edwardsiella tarda reduces resistance to antibiotics and enhances lethality in zebra fish. Journal of Applied Microbiology, 112: 1075–1085. doi: 10.1111/j.1365-2672.2012.05291.x
- Issue published online: 10 MAY 2012
- Article first published online: 20 APR 2012
- Accepted manuscript online: 22 MAR 2012 11:08AM EST
- 2012/0179: received 30 January 2012, revised 14 March 2012 and accepted 15 March 2012
- Edwardsiella tarda;
- lytic transglycosylase;
Aims: The aim of this study was to investigate the role of membrane-bound lytic murein transglycosylase A (MltA) in a bacterial fish pathogen Edwardsiella tarda.
Methods and Results: An mltA in-frame deletion mutant (ΔmltA) and an mltA overexpression strain (mltA+) of Edw. tarda were constructed through double-crossover allelic exchange and by transformation of a low-copy plasmid carrying the intact mltA into the ΔmltA mutant, respectively. Either inactivation or overexpression of MltA in Edw. tarda resulted in elevated sensitivity to β-lactam antibiotics and lower viability in oligotrophic or high osmotic environment than wild-type strain. Autolysis induced by EDTA was reduced in ΔmltA strain, while mltA+ strain was virtually flimsy, indicating that MltA is responsible for the lysis effect. Moreover, mltA+ strain exhibited significant increases in lipopolysaccharide (LPS) biosynthesis and virulence to zebra fish compared with wild-type strain.
Conclusions: The results indicated that MltA plays essential roles in β-lactam antibiotics and environmental stresses resistance, autolysis, LPS biosynthesis and pathogenicity of Edw. tarda. This is the first report that MltA has a virulence-related function in Edw. tarda.
Significance and Impact of the Study: This study provided useful information for further studies on pathogenesis of Edw. tarda.