title: Egg wax from the cattle tick Rhipicephalus (Boophilus) microplus inhibits Pseudomonas aeruginosa biofilm.
abstract: Rhipicephalus (Boophilus) microplus is constantly challenged during its life cycle by microorganisms present in their hosts or in the environment. Tick eggs may be especially vulnerable to environmental conditions because they are exposed to a rich and diverse microflora in the soil. Despite being oviposited in such hostile sites, tick eggs remain viable, suggesting that the egg surface has defense mechanisms against opportunistic and/or pathogenic organisms. R. microplus engorged females deposit a superficial wax layer onto their eggs during oviposition. This egg wax is essential for preventing desiccation as well as acting as a barrier against attack by microorganisms. In this study, we report the detection of anti-biofilm activity of R. microplus egg wax against Pseudomonas aeruginosa PA14. Genes involved in the functions of production and maintenance of the biofilm extracellular matrix, pelA and cdrA, respectively, were markedly downregulated by a tick egg-wax extract. Moreover, this extract strongly inhibited fliC gene expression. Instead of a compact extracellular matrix, P. aeruginosa PA14 treated with egg-wax extract produces a fragile one. Also, the colony morphology of cells treated with egg-wax extract appears much paler and brownish, instead of the bright purple characteristic of normal colonies. Swarming motility was also inhibited by treatment with the egg-wax extract. The inhibition of P. aeruginosa biofilm does not seem to depend on inhibition of the quorum sensing system since mRNA levels of the 3 regulators of this system were not inhibited by egg-wax extract.
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970, Porto Alegre, RS, Brazil.
authors.forename: Karine R
authors.initials: KR
authors.lastname: Zimmer
authors.forename: Alexandre J
authors.initials: AJ
authors.lastname: Macedo
authors.forename: Gianlucca G
authors.initials: GG
authors.lastname: Nicastro
authors.forename: Regina L
authors.initials: RL
authors.lastname: Baldini
authors.forename: Carlos
authors.initials: C
authors.lastname: Termignoni
mesh_terms: D018829:Adhesins, Bacterial / Q000187:drug effects / Q000235:genetics; D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000187:drug effects / Q000235:genetics; D018441:Biofilms / Q000187:drug effects*; D002417:Cattle; D015536:Down-Regulation; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005260:Female; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D008855:Microscopy, Electron, Scanning; D010063:Ovum / Q000737:chemistry* / Q000382:microbiology; D018384:Oxidative Stress; D011550:Pseudomonas aeruginosa / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D012329:RNA, Bacterial / Q000235:genetics; D048494:Rhipicephalus / Q000737:chemistry* / Q000382:microbiology; D014774:Virulence
chemical_list: D018829:Adhesins, Bacterial; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C551088:CdrA protein, Pseudomonas aeruginosa; D012329:RNA, Bacterial
keywords: Biofilm; Egg wax; Protective mechanisms; Pseudomonas aeruginosa; Rhipicephalus (Boophilus) microplus