Effects of Myrcia ovata Cambess. essential oil on planktonic growth of gastrointestinal microorganisms and biofilm formation of Enterococcus faecalis

Bacillus cereus is a foodborne pathogen that often persists in dairy environments and is associated with food poisoning and spoilage. This spore-forming bacterium has a high propensity to develop biofilms onto dairy processing equipment and resists to chemical cleaning and disinfecting. This study deals with the in vitro application of thyme oil-based sanitizer solutions against biofilms formed by B. cereus genotypes which persist in pasteurized-milk processing lines. The effect of Thymus ciliatus essential oil on B. cereus planktonic cells and biofilms was assessed. The oil was tested alone and in combination with organic acids or industrial cleaning agents, in order to improve the removal of B. cereus recurrent genotypes. Minimal inhibitory concentrations of planktonic growth (MICs), biofilm formation (MBIC) and biofilm eradication (MBEC) of oil and organic acids were evaluated by microdilution assays. Thyme oil was more effective than organic acids against B. cereus planktonic growth, biofilm formation and established bio-films. High values of MICs were obtained for the three organic acids tested (3.5-4.5%) in comparison with those of essential oil (0.082-0.088%). The combination of oil with other antimicrobials as acetic acid, NaOH or HNO3 improves their effectiveness against B. cereus biofilms. These oil-based sanitizer solutions allow complete B. cereus biofilm eradication and should be an attractive candidate for the control and removal of biofilms in the dairy envi-ronment.

Download Full-text

Effects of oregano, carvacrol and thymol on Staphylococcus aureus and Staphylococcus epidermidis biofilms

Journal of Medical Microbiology ◽

10.1099/jmm.0.46804-0 ◽

2007 ◽

Vol 56 (4) ◽

pp. 519-523 ◽

Cited By ~ 284

Author(s):

Antonia Nostro ◽

Andrea Sudano Roccaro ◽

Giuseppe Bisignano ◽

Andreana Marino ◽

Maria A. Cannatelli ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Essential Oil ◽

Staphylococcus Epidermidis ◽

Biofilm Formation ◽

Inhibitory Concentration ◽

Oregano Essential Oil ◽

Planktonic Growth ◽

Subinhibitory Concentrations

The aim of this study was to evaluate the effect of oregano essential oil, carvacrol and thymol on biofilm-grown Staphylococcus aureus and Staphylococcus epidermidis strains, as well as the effects of the oils on biofilm formation. For most of the S. aureus (n=6) and S. epidermidis (n=6) strains tested, the biofilm inhibitory concentration (0.125–0.500 %, v/v, for oregano, and 0.031–0.125 %, v/v, for carvacrol and thymol) and biofilm eradication concentration (0.25–1.0 %, v/v, for oregano and 0.125–0.500 %, v/v, for carvacrol and thymol) values were twofold or fourfold greater than the concentration required to inhibit planktonic growth. Subinhibitory concentrations of the oils attenuated biofilm formation of S. aureus and S. epidermidis strains on polystyrene microtitre plates.

Download Full-text