Antimicrobial and anti-biofilm activity of manuka essential oil against <em>Listeria monocytogenes</em> and <em>Staphylococcus aureus</em> of food origin

Abstract

The activity of manuka (Leptospermum scoparium) essential oil (EO) on biofilms of foodborne Listeria monocytogenes and Staphylococcus aureus has been studied. Seven strains of L. monocytogenes and 7 of S. aureus (5 methicillin-resistant) were tested. EO minimal inhibitory concentration (MIC), EO minimal bactericidal concentration (MBC) and biofilm production quantification were determined for each strain by microtiter methods. Moreover, EO Minimum Biofilm Inhibitory Concentration (MBIC) and Minimum Biofilm Eradicating Concentration (MBEC) were determined on 2 L. monocytogenes and 3 S. aureus that showed the best biofilm production. Finally, on 4 strains out of 5 (2 L. monocytogenes and 2 S. aureus) EO Biofilm Reduction Percentage (BRP) vs. untreated controls was assessed after a treatment with EO subinhibitory concentrations. The chemical composition of manuka essential oil was determined by Gas Chromatography- Electron Impact Mass Spectrometry (GCEIMS). The manuka EO demonstrated good antimicrobial activity: L. monocytogenes MIC and MBC were 0.466 mg/ml and 0.933 mg/ml, respectively, whereas S. aureus MIC and MBC were 0.233 mg/ml and 0.466 mg/ml, respectively. Furthermore, L. monocytogenes showed a MBIC of 0.933 mg/ml and a MBEC in the range of 0.933–1.865 mg/ml, whereas S. aureus had a MBIC in the range of 7.461–14.922 mg/ml and a MBEC of 14.922 mg/ml. L. monocytogenes revealed no significant BRP after the treatment with manuka EO, whereas S. aureus showed a BRP higher than 50% with MIC/2 and MIC/4 EO concentrations. These results provide information for feasible manuka EO applications in food production systems.

The Volatile Organic Compounds of Streptomyces spp.: An In-Depth Analysis of Their Antifungal Properties

“…Nevertheless, most of these properties are described in essential oils, not in the isolated compounds that comprise them. For instance, calamenene is a component of several plant essential oils with antimicrobial, antiviral, anti-biofilm, and antioxidant activities [ 32 , 33 , 34 , 35 ]. S-methyl methanethiosulfonate and allyl nonanoate are related to significant antifungal and antibiotic activity, respectively [ 36 , 37 ].…”

“…Similarly, pyrazines have different antimicrobial properties in various applications in the food industry, agriculture, and pharmacy [ 39 , 40 , 41 ]. Special mention should be made of cubenene o 1,2,3,5,6,8a-hexahydro-4,7-dimethyl-1-(1-methylethyl)γ-cadinene((1S-cis)-Naphthalene, which has strong antitumoral activity against ovarian cancer [ 42 ] and antimicrobial bioactivity against different clinical pathogens [ 32 , 43 ], and this compound is identified in various samples in both media and in other strains. The other compounds identified were 2-methylisoborneol or trans-1,10-Dimethyl-trans-9-decalinol (commonly known as geosmin), typically produced by Streptomyces [ 44 ].…”

Antibacterial and antibiofilm activity of Melaleuca alternifolia (tea tree) essential oil against colistin resistant Salmonella enterica serotypes isolated from poultry environmental specimens

“…Antibacterial activity results of TTO were shown as a MIC value and found between 6250-12500 µg/mL (Table 2). Biofilm formation levels of the tested S. enterica serotypes were classified according to Pedonese, Longo [31]'s method as weak, moderate and strong. ODs were interpreted using following formulations: ODs ≤ ODc = no biofilm producers, ODc < ODs < 2ODc = weak biofilm producer, 2ODc < ODs < 3ODc = moderate biofilm producer, ODs ≥ 3ODc = strong biofilm producer.…”