Present address: Department of Medicine, Faculty of Health Sciences, McMaster University, Ontario, Canada.
Biogenic ammonia modifies antibiotic resistance at a distance in physically separated bacteria
Article first published online: 23 JUN 2011
© 2011 Blackwell Publishing Ltd
Volume 81, Issue 3, pages 705–716, August 2011
How to Cite
Bernier, S. P., Létoffé, S., Delepierre, M. and Ghigo, J.-M. (2011), Biogenic ammonia modifies antibiotic resistance at a distance in physically separated bacteria. Molecular Microbiology, 81: 705–716. doi: 10.1111/j.1365-2958.2011.07724.x
- Issue published online: 24 JUL 2011
- Article first published online: 23 JUN 2011
- Accepted manuscript online: 9 JUN 2011 03:22AM EST
- Accepted 30 May, 2011.
Bacteria release low-molecular-weight by-products called secondary metabolites, which contribute to bacterial ecology and biology. Whereas volatile compounds constitute a large class of potential infochemicals, their role in bacteria–bacteria interactions remains vastly unexplored. Here we report that exposure to gaseous ammonia released from stationary-phase bacterial cultures modifies the antibiotic resistance spectrum of all tested Gram-negative and Gram-positive bacteria. Using Escherichia coli K12 as a model organism, and increased resistance to tetracycline as the phenotypic read-out, we demonstrate that exposure to ammonia generated by the catabolism of l-aspartate increases the level of intracellular polyamines, in turn leading to modifications in membrane permeability to different antibiotics as well as increased resistance to oxidative stress. We show that the inability to import ammonia via the Amt gas channel or to synthesize polyamines prevent modification in the resistance profile of aerially exposed bacteria. We therefore provide here the first detailed molecular characterization of widespread, long-range chemical interference between physically separated bacteria.