IN VITRO ACTIVITY OF SPICE EXTRACTS AGAINST ARCOBACTER SPP. AND INFLUENCE ON THEIR BIOFILM FORMATION

Abstract

Several plants are considered to be new resources of substances that can be a potential alternative to combat particularly resistant microorganisms. Arcobacter spp. are dangerous bacteria with pathogenic potential and biofilm formation ability. The aim of this study was to evaluate the antimicrobial activity of six spice extracts against several Arcobacter-strains, including much less literally described strains as well. Among the evaluated spices, significant antibacterial activity of many samples was showed. The clove MetOH/DMSO (extraction in methanol/final dissolution in dimethylsulfoxide) extract had a MIC≥20 mg/mL, nutmeg MetOH/DMSO extract had MIC 10-20 mg/mL, and the highest values were recorded in star anise extract (MIC≥20 mg/mL) after 24 hours of exposure. However, arcobacters were highly resistant to extracts from juniper, nutmeg and anise. Furthermore, the effect of extracts on biofilm formation was monitored using Christensen method. The tested extracts were found to have a dual effect on biofilm formation. The elimination of biofilm formation was observed, however also its stimulation, depending on the type of extract and the bacterial strain. The results indicate a particularly interesting antimicrobial effect of cloves and cinnamon extract (inhibition zones up to 30 mm) against Arcobacter strains. The study shows a promising effect of tested extracts on biofilm formation for the first time.