VOLATILES CONTROL LONG-DISTANCE INTERACTIONS BETWEEN COMPETING BIOFILMS

Biofilms are multicellular bacterial communities embedded in a self-produced extracellular matrix. Cell to cell communication in biofilms is extremely crucial for biofilms formation, development and disassembly. However, little is known about the capability of long-distance interactions between biofilms. Here, we found air-transmittable volatiles produced by Bacillus subtilis playing an important role for the competitions of spatially separated biofilms. More specifically, the volatiles can dramatically inhibit the formation long-distance biofilms of the same specie and a phylogenetically distinct pathogen, the enteropathogenic Escherichia coli (EPEC), sharing the same ecological niche. The inhibition of competing biofilms was dependent on the accumulation of volatiles. Furthermore, the volatiles served as signaling molecules as they decreased the expression of biofilm matrix genes for both inhibited species. Ammonia, a primary volatile produced by B.subtilis, mimicked the activity of the physiological volatiles by inhibiting the formation of B.subtilis and EPEC biofilms in our experiments. We now aim to test what conserved molecular mechanisms are involved in producing and sensing the volatiles, and how these interactions shape soil bacterial communities. Our research exposed an efficient mechanism for communications between physically separated biofilms allowing them to sense and response to their competitors over a large distance.