Evolutionary stability of antibiotic protection in a defensive symbiosis

Proc Natl Acad Sci U S A. 2018 Feb 27;115(9):E2020-E2029. doi: 10.1073/pnas.1719797115. Epub 2018 Feb 14.

Abstract

The increasing resistance of human pathogens severely limits the efficacy of antibiotics in medicine, yet many animals, including solitary beewolf wasps, successfully engage in defensive alliances with antibiotic-producing bacteria for millions of years. Here, we report on the in situ production of 49 derivatives belonging to three antibiotic compound classes (45 piericidin derivatives, 3 streptochlorin derivatives, and nigericin) by the symbionts of 25 beewolf host species and subspecies, spanning 68 million years of evolution. Despite a high degree of qualitative stability in the antibiotic mixture, we found consistent quantitative differences between species and across geographic localities, presumably reflecting adaptations to combat local pathogen communities. Antimicrobial bioassays with the three main components and in silico predictions based on the structure and specificity in polyketide synthase domains of the piericidin biosynthesis gene cluster yield insights into the mechanistic basis and ecoevolutionary implications of producing a complex mixture of antimicrobial compounds in a natural setting.

Keywords: Philanthus; Streptomyces philanthi; antibiotic resistance; defensive symbiosis; protective mutualism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / chemistry*
  • Biological Assay
  • Biological Evolution
  • Ecology
  • Fungi
  • Indoles / chemistry*
  • Microbial Sensitivity Tests
  • Nigericin / analogs & derivatives*
  • Nigericin / chemistry
  • Oxazoles / chemistry*
  • Pyridines / chemistry*
  • Species Specificity
  • Streptomyces / drug effects*
  • Streptomyces / metabolism
  • Symbiosis*
  • Wasps / microbiology*

Substances

  • Anti-Bacterial Agents
  • Indoles
  • Oxazoles
  • Pyridines
  • streptochlorin
  • piericidin A
  • Nigericin

Associated data

  • Dryad/10.5061/dryad.6907h