Evaluation of the antibacterial and sporicidal activity of the essential oils of Copaifera multijuga and Thymus vulgaris against Alicyclobacillus acidoterrestris
2019
Ruiz, S. P. | Machinski Junior, M. | Graton Mikcha, J. M. | Pascoli, I. C. | Silva, A. A. | Santos, I. F. | Nakamura, C. V. | Ueda Nakamura, T. | Anjos, M. M. | Abreu Filho, B. A.
The present work aimed to evaluate the antibacterial activity of the essential oils (EOs) of Copaifera multijuga and Thymus vulgaris against Alicyclobacillus acidoterrestris. The minimum inhibitory concentration (MIC) of the C. multijuga and T. vulgaris EOs were 300 and 500 µg/mL, respectively, and the minimum bactericidal concentration (MBC) of both EOs was >1,000 µg/mL. The best minimum sporicidal concentration (MSC) of C. multijuga was reached at a concentration of 500 µg/mL, with a reduction of 3.07 log CFU/mL. For the EO of T. vulgaris, better results were observed at concentrations higher than 500 µg/mL, and a reduction of 2.05 log CFU/mL was achieved at 1,000 µg/mL. The checkerboard method showed that the combination of EOs and nisin had an additive interaction. The bactericidal activity was confirmed by the death curve. According to the selectivity index, the treatment was less selective for A. acidoterrestris than for Vero cells. The flow cytometry results indicated that the vegetative forms of A. acidoterrestris had a higher incidence with alterations in cell membrane integrity as compared to their spores. When EOs were added to reconstituted orange juice, antibacterial treatment was highly effective and when EOs were combined with nisin, there was a complete reduction of bacterial load. Thus, it is evident that the EOs of C. multijuga and T. vulgaris have potential for use as antibacterial agents against A. acidoterrestris.
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