title: Symbiont-Derived Antimicrobials Contribute to the Control of the Lepidopteran Gut Microbiota.
abstract: Insects develop efficient antimicrobial strategies to flourish in a bacterial world. It has long been proposed that native gut microbiota is an important component of host defense; however, the responsible species have rarely been isolated to elucidate the mechanism of action. Here we show that the dominant symbiotic bacterium Enterococcus mundtii associated with the generalist herbivore Spodoptera littoralis actively secretes a stable class IIa bacteriocin (mundticin KS) against invading bacteria, but not against other gut residents, facilitating the normal development of host gut microbiota. A mundticin-defective strain lost inhibitory activity. Furthermore, purified mundticin cures infected larvae. Thus, the constitutively produced antimicrobials by native extracellular symbionts create a significant chemical barrier inside limiting invader expansion. This unique property also benefits E. mundtii itself by providing a competitive advantage, contributing to its dominance within complex microbial settings and its prevalence across Lepidoptera, and probably promotes the long-term cooperative symbiosis between both parties.
authors.affiliation: College of Animal Sciences, Zhejiang University, Hangzhou 310058, China. Electronic address: yshao@zju.edu.cn.
authors.forename: Yongqi
authors.initials: Y
authors.lastname: Shao
authors.affiliation: College of Animal Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Bosheng
authors.initials: B
authors.lastname: Chen
authors.affiliation: Analysis Center of Agrobiology and Environmental Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
authors.affiliation: Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, 07745 Jena, Germany.
authors.forename: Keishi
authors.initials: K
authors.lastname: Ishida
authors.affiliation: Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, 07745 Jena, Germany; Friedrich Schiller University Jena, 07745 Jena, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Hertweck
authors.affiliation: Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Beutenberg Campus, 07745 Jena, Germany. Electronic address: boland@ice.mpg.de.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Boland
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001430:Bacteriocins / Q000494:pharmacology*; D016983:Enterococcus / Q000187:drug effects*; D000069196:Gastrointestinal Microbiome / Q000187:drug effects*; D007915:Lepidoptera / Q000378:metabolism*; D013559:Symbiosis
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins
keywords: antimicrobial peptide; defensive symbiont; ecological function; insect herbivore