Potential Use and Chemical Analysis of Some Natural Plant Extracts for Controlling Listeria spp. Growth In Vitro and in Food

Abstract

Listeria are Gram-negative intracellular foodborne pathogens that can cause invasive infections with high mortality rates. In this work, the antibacterial activity of ten essential oils, infusion extracts, and decoction extracts of some medicinal plants was tested against Listeria monocytogenes and listeria ivanovii strains. The effects of different physical conditions including temperature, pH, sodium chloride, and some organic acids were studied. The results showed that the water extracts gave the maximum bacterial inhibition, while ethanolic extract was inactive against the tested Listeria spp. The antibiotic sensitivity of L. monocytogenes LMG10470 and L. ivanovii LMZ11352 was tested against five antibiotics including imipenem, levofloxacin, amikacin, ampicillin, and amoxicillin. Imipenem was the most effective antibiotic, resulting in inhibition zones of 40 mm and 31 mm for L. monocytogenes and L. ivanovii, respectively. When imipenem mixed with Syzygium aromaticum oil, Salvia officinalis oil, Pimpinella anisum infusion, and Mentha piperita infusion each, the water extract of Moringa oleifera leaves and seeds against LMG10470 and LMZ11352 resulted in broader antibacterial activity. The antimicrobial activity of both Pimpinella anisum and Mentha piperita plant extracts is related to a variety of bioactive compounds indicated by gas chromatography-mass spectrometry analysis of these two plant extracts. These two plant extracts seemed to contain many chemical compounds elucidated by gas chromatography-mass spectrometry (GC-MS) and infrared radiation spectra. These compounds could be classified into different chemical groups such as ethers, heterocyclic compounds, aromatic aldehydes, condensed heterocyclic compounds, ketones, alicyclic compounds, aromatics, esters, herbicides, saturated fatty acids, and unsaturated fatty acids. The use of these natural compounds seems to be a useful technological adjuvant for the control of Listeria spp. in foods.

Keywords: GC-MS; IR spectra; L. ivanovii LMZ11352; L. monocytogenes LMG10470; essential oils; food-borne bacteria; imipenem; plant extracts.

Figure 1

Thermal death point of L. monocytogenes LMG10470 and L. ivanovii LMZ11352 after 15 min of exposure to different temperatures different temperature exposure.

Figure 2

Effect of different pH values on L. monocytogenes LMG10470 and L. ivanovii LMZ11352 growth.

Figure 3

Effect of different NaCl concentrations on L. monocytogenes LMG10470 and L. ivanovii LMZ11352 growth.

Figure 4

Effect of citric acid concentration on L. monocytogenes LMG10470 and L. ivanovii LMZ11352 growth.

Figure 5

Effect of oxalic acid concentrations on L. monocytogenes LMG10470 and L. ivanovii LMZ11352 growth.

Figure 6

Effect of salicylic acid concentrations on L. monocytogenes LMG10470 and L. ivanovii LMZ11352 growth.

Figure 7

Antibacterial activity of different concentrations of infusion extracts of Mentha piperita and Pimpinella anisum against L. monocytogenes LMG10470 and L. ivanovii LMZ11352 by the disc assay method. The numbers 1, 2, 3, 4, and 5 show inhibition zone diameters of 10%, 25%, 50%, 75%, and 100%.

Figure 8

Growth curves of (A) Pimpinella anisum, (B) Mentha piperita, (C) Zingiber officinalis, (D) Rosemarinus officinalis, (E) Salvia officinalis, and (F) Martricaria chamomilla against L. monocytogenes LMG10470 in nutrient broth incubated at 37 °C for 24 h.

Figure 8

Growth curves of (A) Pimpinella anisum, (B) Mentha piperita, (C) Zingiber officinalis, (D) Rosemarinus officinalis, (E) Salvia officinalis, and (F) Martricaria chamomilla against L. monocytogenes LMG10470 in nutrient broth incubated at 37 °C for 24 h.

Figure 9

Growth curves of (A) Pimpinella anisum, (B) Mentha piperita, (C) Zingiber officinalis, (D) Rosemarinus officinalis, (E) Salvia officinalis, and (F) Martricaria chamomilla against L. ivanovii LMZ11352 in nutrient broth incubated at 37 °C for 24 h.

Figure 9

Growth curves of (A) Pimpinella anisum, (B) Mentha piperita, (C) Zingiber officinalis, (D) Rosemarinus officinalis, (E) Salvia officinalis, and (F) Martricaria chamomilla against L. ivanovii LMZ11352 in nutrient broth incubated at 37 °C for 24 h.

Figure 10

Quantitative inhibition of decoction extract of the test medicinal plants against L. monocytogenes LMG10470. (A) Pimpinella anisum, (B) Rosemarinus officinalis, (C) Cinnamum zeylanieum, and (D) Syzygium aromaticum.

Figure 10

Quantitative inhibition of decoction extract of the test medicinal plants against L. monocytogenes LMG10470. (A) Pimpinella anisum, (B) Rosemarinus officinalis, (C) Cinnamum zeylanieum, and (D) Syzygium aromaticum.

Figure 11

Quantitative inhibition of decoction extract of test medicinal plants against L. ivanovii LMZ11352. (A) Pimpinella anisum, (B) Rosemarinus officinalis, (C) Cinnamum zeylanieum, and (D) Syzygium aromaticum.

Figure 12

Antibacterial activity of Moringa oleifera extracts (leaves) against L. monocytogenes LMG10470 and L. ivanovii LMZ11352 using disc assay and agar well diffusion methods. WE: water extract of leaves. ME: methanol extract of leaves.

Figure 13

Antibacterial activity of Moringa oleifera extracts (Seeds) against L. monocytogenes LMG10470 and L. ivanovii LMZ11352 using disc assay and agar well diffusion methods. WE: water extract of seeds. ME: methanol extract of seeds.

Figure 14

Antibacterial activity of mixed combinations of natural extracts and an antibiotic (imipenem) against L. monocytogenes by the disc assay method. (A) imipenem against L. monocytogenes. (B) (imipenem–natural extract) mixture combination against L. monocytogenes. (C) natural extract against L. monocytogenes.

Figure 14

Antibacterial activity of mixed combinations of natural extracts and an antibiotic (imipenem) against L. monocytogenes by the disc assay method. (A) imipenem against L. monocytogenes. (B) (imipenem–natural extract) mixture combination against L. monocytogenes. (C) natural extract against L. monocytogenes.

Figure 15

Antibacterial activity of mixed combinations of natural extracts and an antibiotic (imipenem) against L. ivanovii by the disc assay method. (A): imipenem against L. ivanovii. (B): (imipenem—natural extract) mixture combination against L. ivanovii. (C): natural extract against L. ivanovii.

Figure 15

Antibacterial activity of mixed combinations of natural extracts and an antibiotic (imipenem) against L. ivanovii by the disc assay method. (A): imipenem against L. ivanovii. (B): (imipenem—natural extract) mixture combination against L. ivanovii. (C): natural extract against L. ivanovii.

Figure 16

IR spectrum of Pimpinella anisum. Growth of L. monocytogenes LMG10470 (CFU/mL) in the presence of L. delbreukii subsp. bulgaricus Z55, E. faecium NM2, and L. plantarum LPS10 in vitro.

Figure 17

IR spectrum of Mentha pipertia.