Bacteriocin‐mediated interactions within and between coexisting species

• Published in: Ecology and evolution Vol. 2; no. 10; pp. 2521 - 2526
• Main Authors: Hawlena, Hadas, Bashey, Farrah, Lively, Curtis M.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.10.2012; Blackwell Publishing Ltd
• Subjects: Bacteria; Bacteriocins; Colonies; Communities; Competition; Ecological monitoring; entomopathogenic bacteria; Evolution; Genetic variability; Genotypes; Interspecific; interspecific interactions; intraspecific interactions; Measuring instruments; Original Research; recognition mechanisms; Soils; Species; Toxins; Xenorhabdus; Xenorhabdus bacteria; Indiana; United States > US; Israel; Xenorhabdus bacteria; Bacteriocins; recognition mechanisms; entomopathogenic bacteria; intraspecific interactions; interspecific interactions
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.354

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. Bacteriocins are bacteriocidal toxins released by almost all bacteria. They are known to have a narrow range of killing, but whether this narrow range of action falls mostly within or mostly between species in natural communities is an open problem with important ecological and evolutionary implications. Here we establish the existence of both intraspecific and interspecific bacteriocin‐mediated interactions at biologically relevant scales in nature, and show that inhibitions between conspecifics are significantly more common than between heterospecifics, using entomopathogenic bacteria (Xenorhabdus bovienii and X. koppenhoeferi). These results suggest that bacteriocins may serve to mediate bacterial community interactions and that a major role of bacteriocins in nature is to mediate intraspecific microbial dynamics.