Journal Highlight: Interspecies competition: bacterial 'turf wars'
The immense bacterial diversity within the soil leads to unavoidable interspecies interactions, which ultimately form a structured microbial community. Generation of antagonistic and mutualistic behaviours, mediated by exchange of small diffusible secondary metabolites, enables bacterial adaptation to the complex communal life. Such communication can induce resistance to various antibiotics, or can eliminate rival bacterial species competing for limited nutrients.
Soil bacterial colonies employ sophisticated tactics to wage war against rival species, say researchers. Ilana Kolodkin-Gal of Israel's Weizmann Institute of Science and colleagues examined interactions between two species commonly found in soil, Bacillus subtilis and Bacillus simplex. They found that B. subtilis communities dispatch highly mobile cells that surround and ultimately eradicate B. simplex biofilms. Subsequent analysis enabled Kolodkin-Gal and colleagues to identify three molecules produced by B. subtilis as part of its attack, including two 'cannibal toxins'. These molecules, which were previously presumed to help this bacterium police its own population growth, actually appear to be far more toxic to other Bacillus species. Interestingly, B. subtilis cells on the front lines discard genetic material that could inhibit their attack on B. simplex, presumably reacquiring these DNA fragments when their rivals are eliminated.