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Oregano essential oil-pectin edible films as anti-quorum sensing and food antimicrobial agents.

Alvarez MV, Ortega-Ramirez LA, Gutierrez-Pacheco MM, Bernal-Mercado AT, Rodriguez-Garcia I, Gonzalez-Aguilar GA, Ponce A, Moreira Mdel R, Roura SI, Ayala-Zavala JF - Front Microbiol (2014)

Bottom Line: Choleraesuis.Additionally, the application of pectin-OEO films was effective reducing total coliforms, yeast, and molds of shrimp and cucumber slices stored at 4°C during 15 d.These results demonstrated the potential of pectin films enriched with OEO as food related microorganisms and QS inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas - Grupo de Investigación en Ingeniería en Alimentos, Facultad de Ingeniería, Universidad Nacional de Mar del Plata Mar del Plata, Argentina.

ABSTRACT
Edible films can be used as carriers for antimicrobial compounds to assure food safety and quality; in addition, pathogenesis of food bacteria is related to a cell to cell communication mechanism called quorum sensing (QS). Oregano essential oil (OEO) has proved to be useful as food antimicrobial; however, its food applications can be compromised by the volatile character of its active constituents. Therefore, formulation of edible films containing OEO can be an alternative to improve its food usages. QS inhibitory activity of OEO and pectin-OEO films was evaluated using Chromobacterium violaceum as bacterial model. Additionally, antibacterial activity was tested against Escherichia coli O157:H7, Salmonella Choleraesuis, Staphylococcus aureus, and Listeria monocytogenes. OEO was effective to inhibit bacterial growth at MIC of 0.24 mg/mL for all tested bacteria and MBC of 0.24, 0.24, 0.48, and 0.24 mg/mL against E. coli O157:H7, S. Choleraesuis, S. aureus, and L. monocytogenes, respectively. Pectin-films incorporated with 36.1 and 25.9 mg/mL of OEO showed inhibition diameters of 16.3 and 15.2 mm for E. coli O157:H7; 18.1 and 24.2 mm for S. Choleraesuis; 20.8 and 20.3 mm for S. aureus; 21.3 and 19.3 mm for L. monocytogenes, respectively. Pectin-OEO film (15.7 mg/mL) was effective against E. coli O157:H7 (9.3 mm), S. aureus (9.7 mm), and L. monocytogenes (9.2 mm), but not for S. Choleraesuis. All concentrations of OEO (0.0156, 0.0312, 0.0625 and 0.125 mg/mL) and pectin-OEO films (15.7, 25.9 and 36.1 mg/mL) showed a significant anti-QS activity expressed as inhibition of violacein production by C. violaceum. Additionally, the application of pectin-OEO films was effective reducing total coliforms, yeast, and molds of shrimp and cucumber slices stored at 4°C during 15 d. These results demonstrated the potential of pectin films enriched with OEO as food related microorganisms and QS inhibitors.

No MeSH data available.


Related in: MedlinePlus

(A) Inhibition of violacein production of C. violaceum exposed to different concentrations of OEO enriched pectin films in LB broth, using films prepared by incorporation of 15.7, 25.9, and 36.1 mg/mL of OEO. Different letters among bars indicated significant differences (p < 0.05). (B)C. violaceum cell viability after incubation in LB broth enriched with different concentrations of OEO enriched films in LB broth. Different letters among bars indicated significant differences (p < 0.05).
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Figure 2: (A) Inhibition of violacein production of C. violaceum exposed to different concentrations of OEO enriched pectin films in LB broth, using films prepared by incorporation of 15.7, 25.9, and 36.1 mg/mL of OEO. Different letters among bars indicated significant differences (p < 0.05). (B)C. violaceum cell viability after incubation in LB broth enriched with different concentrations of OEO enriched films in LB broth. Different letters among bars indicated significant differences (p < 0.05).

Mentions: Figure 1A shows the capacity of OEO to inhibit violacein production from C. violaceum exposed to different concentrations (0.0156, 0.0312, 0.0625, and 0.125 mg/mL). To evaluate whether the inhibition of violacein production owed to the QS mechanism inhibition or to microbial growth reduction, the C. violaceum concentration was also determined. An inverse relationship between pigment production and the applied OEO concentrations was noticed, compared with control samples. All the tested OEO concentrations showed a significant drop in violacein production even the lowest one (0.0156 mg/mL) which reduced pigment production by more than 50%. In addition, the cell viability (Figure 1B) of C. violaceum was not affected at concentrations of 0.156, 0.032, and 0.0625; only the highest concentration (0.125 mg/mL) inhibited the growth reducing the bacterial counts (7 log CFU/mL) after the incubation period. Similarly, pectin-OEO films showed a significant inhibition of violacein production (Figure 2) compared with controls. All pectin films added with 15.7, 25.9, and 36.1 mg/mL of OEO were tested at concentrations of 0.25, 0.5, 1, and 2 mg/mL, and all of them were effective reducing the violacein production. No differences were observed among the concentrations of 0.5, 1, and 2 mg/mL of pectin films added with 15.7, 25.9, and 36.1 mg/mL of OEO showing the highest inhibition percent (more than 90%) of the violacein production. With respect to the effect of the pectin-OEO films on the C. violaceum viability (Figure 2B), it was observed that for all the pectin-OEO films the concentration of 0.25 mg/mL inhibited QS without affecting the cellular viability, in addition, the concentrations of 0.5, 1, and 2 mg/mL of the pectin films added with 15.7 mg/mL of OEO did not affect cellular viability and affected violacein production. On the other hand, the inhibition on pigment production exerted by 25.9 and 36.1 mg/mL pectin-OEO films applied at ≥ 0.5 mg/mL showed significant (p < 0.05) antibacterial effect instead of a blockage of QS mechanism.


Oregano essential oil-pectin edible films as anti-quorum sensing and food antimicrobial agents.

Alvarez MV, Ortega-Ramirez LA, Gutierrez-Pacheco MM, Bernal-Mercado AT, Rodriguez-Garcia I, Gonzalez-Aguilar GA, Ponce A, Moreira Mdel R, Roura SI, Ayala-Zavala JF - Front Microbiol (2014)

(A) Inhibition of violacein production of C. violaceum exposed to different concentrations of OEO enriched pectin films in LB broth, using films prepared by incorporation of 15.7, 25.9, and 36.1 mg/mL of OEO. Different letters among bars indicated significant differences (p < 0.05). (B)C. violaceum cell viability after incubation in LB broth enriched with different concentrations of OEO enriched films in LB broth. Different letters among bars indicated significant differences (p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4269197&req=5

Figure 2: (A) Inhibition of violacein production of C. violaceum exposed to different concentrations of OEO enriched pectin films in LB broth, using films prepared by incorporation of 15.7, 25.9, and 36.1 mg/mL of OEO. Different letters among bars indicated significant differences (p < 0.05). (B)C. violaceum cell viability after incubation in LB broth enriched with different concentrations of OEO enriched films in LB broth. Different letters among bars indicated significant differences (p < 0.05).
Mentions: Figure 1A shows the capacity of OEO to inhibit violacein production from C. violaceum exposed to different concentrations (0.0156, 0.0312, 0.0625, and 0.125 mg/mL). To evaluate whether the inhibition of violacein production owed to the QS mechanism inhibition or to microbial growth reduction, the C. violaceum concentration was also determined. An inverse relationship between pigment production and the applied OEO concentrations was noticed, compared with control samples. All the tested OEO concentrations showed a significant drop in violacein production even the lowest one (0.0156 mg/mL) which reduced pigment production by more than 50%. In addition, the cell viability (Figure 1B) of C. violaceum was not affected at concentrations of 0.156, 0.032, and 0.0625; only the highest concentration (0.125 mg/mL) inhibited the growth reducing the bacterial counts (7 log CFU/mL) after the incubation period. Similarly, pectin-OEO films showed a significant inhibition of violacein production (Figure 2) compared with controls. All pectin films added with 15.7, 25.9, and 36.1 mg/mL of OEO were tested at concentrations of 0.25, 0.5, 1, and 2 mg/mL, and all of them were effective reducing the violacein production. No differences were observed among the concentrations of 0.5, 1, and 2 mg/mL of pectin films added with 15.7, 25.9, and 36.1 mg/mL of OEO showing the highest inhibition percent (more than 90%) of the violacein production. With respect to the effect of the pectin-OEO films on the C. violaceum viability (Figure 2B), it was observed that for all the pectin-OEO films the concentration of 0.25 mg/mL inhibited QS without affecting the cellular viability, in addition, the concentrations of 0.5, 1, and 2 mg/mL of the pectin films added with 15.7 mg/mL of OEO did not affect cellular viability and affected violacein production. On the other hand, the inhibition on pigment production exerted by 25.9 and 36.1 mg/mL pectin-OEO films applied at ≥ 0.5 mg/mL showed significant (p < 0.05) antibacterial effect instead of a blockage of QS mechanism.

Bottom Line: Choleraesuis.Additionally, the application of pectin-OEO films was effective reducing total coliforms, yeast, and molds of shrimp and cucumber slices stored at 4°C during 15 d.These results demonstrated the potential of pectin films enriched with OEO as food related microorganisms and QS inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas - Grupo de Investigación en Ingeniería en Alimentos, Facultad de Ingeniería, Universidad Nacional de Mar del Plata Mar del Plata, Argentina.

ABSTRACT
Edible films can be used as carriers for antimicrobial compounds to assure food safety and quality; in addition, pathogenesis of food bacteria is related to a cell to cell communication mechanism called quorum sensing (QS). Oregano essential oil (OEO) has proved to be useful as food antimicrobial; however, its food applications can be compromised by the volatile character of its active constituents. Therefore, formulation of edible films containing OEO can be an alternative to improve its food usages. QS inhibitory activity of OEO and pectin-OEO films was evaluated using Chromobacterium violaceum as bacterial model. Additionally, antibacterial activity was tested against Escherichia coli O157:H7, Salmonella Choleraesuis, Staphylococcus aureus, and Listeria monocytogenes. OEO was effective to inhibit bacterial growth at MIC of 0.24 mg/mL for all tested bacteria and MBC of 0.24, 0.24, 0.48, and 0.24 mg/mL against E. coli O157:H7, S. Choleraesuis, S. aureus, and L. monocytogenes, respectively. Pectin-films incorporated with 36.1 and 25.9 mg/mL of OEO showed inhibition diameters of 16.3 and 15.2 mm for E. coli O157:H7; 18.1 and 24.2 mm for S. Choleraesuis; 20.8 and 20.3 mm for S. aureus; 21.3 and 19.3 mm for L. monocytogenes, respectively. Pectin-OEO film (15.7 mg/mL) was effective against E. coli O157:H7 (9.3 mm), S. aureus (9.7 mm), and L. monocytogenes (9.2 mm), but not for S. Choleraesuis. All concentrations of OEO (0.0156, 0.0312, 0.0625 and 0.125 mg/mL) and pectin-OEO films (15.7, 25.9 and 36.1 mg/mL) showed a significant anti-QS activity expressed as inhibition of violacein production by C. violaceum. Additionally, the application of pectin-OEO films was effective reducing total coliforms, yeast, and molds of shrimp and cucumber slices stored at 4°C during 15 d. These results demonstrated the potential of pectin films enriched with OEO as food related microorganisms and QS inhibitors.

No MeSH data available.


Related in: MedlinePlus