Mandarin essential oils inhibit quorum sensing and virulence factors of Pseudomonas aeruginosa

• Citrus reticulata essential oils inhibit Pseudomonas aeruginosa biofilm formation.
• The biofilm decrease is due to Quorum sensing (QS) inhibition.
• C. reticulata essential oils inhibit QS autoinducer production and elastase activity.
• C. reticulata effects may be due to the total EOs compounds more than the limonene.
• The EOPD of C. reticulata with few commercial application has the better antipathogenic activity.

Pseudomonas aeruginosa produces biofilm and several virulence factors coordinated by quorum sensing (QS) in food. The interruption of QS is a target to control the bacterial virulence. Chemical preservatives used to control biofilm give rise to several food safety problems. For this reason, essential oils (EOs), generally recognized as safe products, are a hopeful alternative. The aim of this work was to determine the chemical composition of mandarin EOs obtained by cold-pressing (EOP) and cold-pressing followed by steam distillation (EOPD) and their antipathogenic properties against P. aeruginosa. Both EOs contained the highest quantities of monoterpene hydrocarbons, mainly limonene, followed by γ-terpinene, myrcene and α-pinene. Although the EOs were not able to inhibit the bacterial growth at 4 mg/mL, EOP and EOPD significantly inhibited the P. aeruginosa biofilm formation at 0.1 mg/mL. In addition to the EOs inhibited biofilm cell viability (41%), AHL production (33%) and resulted in higher than 75% reduction in elastase enzyme activity. In conclusion, Citrus reticulata EOs are suitable alternatives to chemical additives for general use in the food industry.