We showed that aerial exposure to volatile and diffusible gaseous ammonia modifies the antibiotic resistance pattern of distant recipient Gram-negative and Gram-positive bacteria, including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtillis. We demonstrated that ammonia uptake enhance the intracellular production of polyamines, which subsequently led to transient, non-inherited modification of metabolism and modifications in antibiotic and oxidative stress resistance profiles in all tested, aerially exposed recipient bacteria (Fig.5). Ammonia therefore constitutes the first characterized volatile signal involved in long-range inter-bacterial chemical communication perception and could constitute a biotic cue allowing not only to modulate antibiotic resistance, but also to acquire competitive abilities in densely populated environments.
Volatile compounds are potentially ideal “infochemicals” able to be diffused in heterogeneous environments (soil, gut, etc.) colonized by bacteria. Our study demonstrates that volatile compounds can modify bacterial metabolism and affect bacterial biology and ecology in physically separated bacteria.