Abstract
Utilization of sublethal concentrations of cinnamon essential oil (CEO) for food preservation has been proposed. However, exposure to stressful, sublethal growth conditions may induce bacterial tolerance to homologous or heterologous stressing agents. Hence, the ability of CEO to stimulate bacterial stress response was evaluated in the current work. Staphylococcus aureus was exposed to 1/4 and 1/2 of the minimum inhibitory concentration (MIC, 500 μL/L) of CEO for 18 h. It was found that overnight habituation to CEO failed to induce direct tolerance and cross-tolerance to lactic acid (pH 4.5), NaCl (10 g/100 mL) and high temperature (45 °C) in S. aureus. Likewise, S. aureus cells subjected to successive habituation with increasing amounts (1/16 MIC to 2× MIC) of CEO developed no direct tolerance. Taken together, CEO has no inductive effect on the acquisition of stress tolerance in S. aureus.
Highlights
Staphylococcus aureus is a common cause for foodborne disease due to the capacity of certain strains to produce staphylococcal enterotoxins [1]
The capacity of S. aureus to acquire tolerance to many antimicrobial procedures employed by the food industry to ensure food safety has motivated the research into natural Essential oils (EOs) to control this bacterium in foods [23]
cinnamon essential oil (CEO) has been confirmed as a strong antimicrobial agent due to its ability to disrupt bacterial cell membrane and metabolic activity [28]
Summary
Staphylococcus aureus is a common cause for foodborne disease due to the capacity of certain strains to produce staphylococcal enterotoxins [1]. S. aureus is notorious for its ability to develop resistance to antibiotics [2]. This bacterium is able to mount tolerance to salt, heat and acid stresses when exposed to sublethal environmental conditions [3,4]. Essential oils (EOs) have received worldwide attention for their remarkable antimicrobial capacity. Cinnamon essential oil (CEO) stood out for its antibacterial efficacy against S. aureus [7,8]. CEO exhibited a satisfactory antimicrobial performance on methicillin-resistant S. aureus and its biofilm [9]. Habituation to a sublethal stress can confer bacteria tolerance to the same type of stress (direct tolerance) or seemingly unrelated stresses (cross tolerance) [13,14]
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