title: Antibiotic production by myxobacteria plays a role in predation.
abstract: Myxobacteria are predatory and are prolific producers of secondary metabolites. Here, we tested a hypothesized role that secondary metabolite antibiotics function as weapons in predation. To test this, a Myxococcus xanthus Δta1 mutant, blocked in antibiotic TA (myxovirescin) production, was constructed. This TA(-) mutant was defective in producing a zone of inhibition (ZOI) against Escherichia coli. This shows that TA is the major M. xanthus-diffusible antibacterial agent against E. coli. Correspondingly, the TA(-) mutant was defective in E. coli killing. Separately, an engineered E. coli strain resistant to TA was shown to be resistant toward predation. Exogenous addition of spectinomycin, a bacteriostatic antibiotic, rescued the predation defect of the TA(-) mutant. In contrast, against Micrococcus luteus the TA(-) mutant exhibited no defect in ZOI or killing. Thus, TA plays a selective role on prey species. To extend these studies to other myxobacteria, the role of antibiotic corallopyronin production in predation was tested and also found to be required for Corallococcus coralloides killing on E. coli. Next, a role of TA production in myxobacterial fitness was assessed by measuring swarm expansion. Here, the TA(-) mutant had a specific swarm rate reduction on prey lawns, and thus reduced fitness, compared to an isogenic TA(+) strain. Based on these observations, we conclude that myxobacterial antibiotic production can function as a predatory weapon. To our knowledge, this is the first report to directly show a link between secondary metabolite production and predation.
authors.affiliation: Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA.
authors.forename: Yao
authors.initials: Y
authors.lastname: Xiao
authors.forename: Xueming
authors.initials: X
authors.lastname: Wei
authors.forename: Richard
authors.initials: R
authors.lastname: Ebright
authors.forename: Daniel
authors.initials: D
authors.lastname: Wall
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism*; D000898:Antibiosis; D015169:Colony Count, Microbial; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects; D055786:Gene Knockout Techniques; D007783:Lactones / Q000378:metabolism; D050296:Microbial Viability / Q000187:drug effects; D016982:Micrococcus luteus / Q000187:drug effects; D009231:Myxococcales / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D007783:Lactones; C532894:corallopyronin A; C036969:myxovirescin A