Antimicrobial activity of some essential oils against Streptococcus agalactiae, an important pathogen for fish farming in Brazil

ABSTRACT

The antimicrobial activity of the essential oils from Lippia alba, Lippia sidoides, Mentha piperita, Ocimum gratissimum and Zingiber officinale was tested against Streptococcus agalactiae. The major compounds in the oils, identified by gas chromatography and mass spectrometry (GC/MS), were geranial (25.4%), neral (16.6%) and caryophyllene oxide (16.0%) in L. alba; thymol (76.6%), p-cymene (6.3%) and β-caryophyllene (5.0%) in L. sidoides; menthol (30.5%), menthyl acetate (14.6%), pulegone (14.2%) and menthone (12.9%) in M. piperita; eugenol (43.3%), 1,8-cineole (28.2%) and β-selinene (5.5%) in O. gratissimum; and geranial (23.2%), neral (16.7%) and 1,8-cineole (15.8%) in Z. officinale. All essential oils evaluated showed bactericidal action against S. agalactiae with minimum inhibitory concentration (MIC) ranging from 312.5–2,500 μg mL⁻¹ and minimum bactericidal concentration (MBC) ranging from 416.7–2,500 μg mL⁻¹. In this study, L. sidoides essential oil showed the better results against S. agalactiae.

KEYWORDS:

• Medicinal plants
• essential oil composition
• antimicrobial activity
• group B Streptococcus

Acknowledgments

Dr. Marcelo Róseo de Oliveira from Embrapa Amazônia Ocidental, for assistance in distilling the essential oils and to Marcelly Cristina da Silva Santos, from Embrapa Agroindústria de Alimentos, for assistance in editing and reviewing the table of chemical composition of essential oils.

Disclosure statement

No potential conflicts of interest was reported by the authors.

Additional information

Funding

This work was supported by the Embrapa - Brazilian Agricultural Research Corporation [#MP2 02.12.01.020.00.00] and FINEP [#DARPA project 01.09.0472.00]