Bacteriocin-mediated interactions within and between coexisting species


  • This research was supported by NSF DEB 0515832 and 0919015 and via the Indiana METACyt Initiative of Indiana University, funded in part through a major grant from the Lilly Endowment, Inc. to C. M. L, and F. B. H. H. was supported by a Fulbright fellowship from United States-Israel Educational Foundation and BIKURA fellowship from the Israel Science Foundation.


Hadas Hawlena, Department of Life Sciences, Ben Gurion University of the Negev, 800 Sderot David Ben Gurion Av., P.O. Box 653, Beer-Sheva 84105, Israel. Tel: +972 8 6479226; Fax: +972 8 6461362;E-mail:


Bacteriocins are bacteriocidal toxins released by almost all bacteria. They are thought to have a narrow range of killing, but as bacteriocin-mediated interactions have been rarely studied at biologically relevant scales, whether this narrow range of action falls mostly within or mostly between coexisting species in natural communities is an open question with important ecological and evolutionary implications. In a previous study, we systematically sampled Xenorhabdus bacteria along a hillside and found evidence for genotypic variability and bacteriocin-mediated interactions within Xenorhabdus bovienii and X. koppenhoeferi colonies that were collected only a few meters apart. In contrast, colonies that were isolated from the same soil sample were always genetically similar and showed no inhibitions. Here, we conducted pairwise growth-inhibition assays within and between seven X. bovienii and five X. koppenhoeferi colonies that were isolated from different soil samples; all seven X. bovienii colonies and at least three of the X. koppenhoeferi have been distinguished as distinct genotypes based on coarse-grain genomic markers. We found signatures for both conspecific and heterospecific bacteriocin inhibitions in this natural community of Xenorhabdus bacteria, but intraspecific inhibitions were significantly more common than interspecific inhibitions. These results suggest that bacteriocins have a major role in intraspecific competition in nature, but also suggest that bacterocins are important in mediating interspecific interactions among coexisting species in natural communities.