Mechanisms of Bacterial (Serratia marcescens) Attachment to, Migration along, and Killing of Fungal Hyphae

RON, SAPIR; KIJNER, NITZAN; HAREL, AMNON; GARCÍA VÉSCOVI, ELEONORA; HOVER, TAL; SANDOVSKY, HANI; MITIAGIN, YULIA; SHANKS, ROBERT M.Q.; OSHEROV, NIR; MAYA, TAL; SHADKCHAN, YANA; FICHTMAN, BORIS; BRUNA, ROBERTO

APPLIED AND ENVIRONMENTAL MICROBIOLOGY

AMER SOC MICROBIOLOGY

Lugar: Washington; Año: 2016 vol. 18 p. 2585 - 2594

0099-2240

We have found a remarkable capacity for the ubiquitous Gram-negative rod bacteriumSerratia marcescensto migrate along and kill the mycelia of zygomycete molds. This migration was restricted to zygomycete molds and several basidiomycete species. No migration was seen on any molds of the phylum Ascomycota.S. marcescensmigration did not require fungal viability or surrounding growth medium, as bacteria migrated along aerial hyphae as well.S. marcescensdid not exhibit growth tropism toward zygomycete mycelium. Bacterial migration along hyphae proceeded only when the hyphae grew into the bacterial colony.S. marcescenscells initially migrated along the hyphae, forming attached microcolonies that grew and coalesced to generate a biofilm that covered and killed the mycelium. Flagellum-defective strains ofS. marcescenswere able to migrate along zygomycete hyphae, although they were significantly slower than the wild-type strain and were delayed in fungal killing. Bacterial attachment to the mycelium does not necessitate type 1 fimbrial adhesion, since mutants defective in this adhesin migrated equally well as or faster than the wild-type strain. Killing does not depend on the secretion ofS. marcescenschitinases, as mutants in which all three chitinase genes were deleted retained wild-type killing abilities. A better understanding of the mechanisms by whichS. marcescensbinds to, spreads on, and kills fungal hyphae might serve as an excellent model system for such interactions in general; fungal killing could be employed in agricultural fungal biocontrol.