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Antimicrobial Oil-in-Water Nanoemulsions: Synergistic Effect of Nisin and Carvacrol against Bacillus subtilis



Author(s)

Marcos Antonio Neves^{1, 2}, Porsry Ung^{1, 3}, Kunihiko Uemura², Chieko Takahashi², Isao Kobayashi², Patrizia Romano4 and Mitsutoshi Nakajima^{1, 2}

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DOI:10.17265/2159-5828/2016.02.002

1. Graduate School of Life and Environmental Sciences, Alliance for Research on North Africa, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan 2. Food Engineering Division, National Food Research Institute, NARO, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan 3. International Master EDAMUS - Sustainable Management of Food Quality, Univ. of Montpellier, 15 Av. Charles Flahault, B.P. 14491, 34093 Montpellier, France 4. School of Agricultural, Forest, Food and Environmental Sciences (SAFE), University of Basilicata, Via Ateneo Lucano, 10, 85100 Potenza, Italy

The aim of this study was to elucidate the mode of action of two antimicrobial compounds, nisin, which is hydrophilic, and the lipophilic compound carvacrol. For that purpose, both antimicrobials were loaded into Oil-in-/Water nanoemulsions, and their antimicrobial activity against Bacillus subtilis was investigated. The experimental results indicated that the O/W nanoemulsions loaded with both, nisin and carvacrol, having Sauter mean diameter (d3,2) of around 120 nm, were considerably stable under the conditions investigated (up to 1 week storage at room temperature). The interfacial tension between nisin aqueous solutions and soybean oil could be reduced up to 12 mN/m, as compared to that of pure water and soybean oil (21 mN/m), so that demonstrating the potential of nisin to be used as emulsifier. The results obtained for O/W nanoemulsions loaded with both antimicrobial compounds indicated a reduction of nearly two log cycles (around 100 times) on B. subtilis population upon incubation for 24 h, compared to the blank (10 mM phosphate buffer).

Antimicrobial, nanoemulsion, nisin, carvacrol, synergy, Bacillus spp.