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The Antibacterial Activity of Chitosan Products Blended with Monoterpenes and Their Biofilms against Plant Pathogenic Bacteria.

Badawy ME, Rabea EI, Taktak NE, El-Nouby MA - Scientifica (Cairo) (2016)

Bottom Line: The antibacterial activity was evaluated in vitro by the agar dilution technique as a minimum inhibitory concentration (MIC) that was found to be dependent on the type of the microorganism tested.The most active product of chitosan was used for biofilm production enriched with geraniol and thymol (0.1 and 0.5%) and the films were also evaluated against the tested bacteria.The biological bioactivities summarized here may provide novel insights into the functions of chitosan and some monoterpenes and potentially allow their use for food protection from microbial attack.

View Article: PubMed Central - PubMed

Affiliation: Department of Pesticide Chemistry and Technology, Faculty of Agriculture, Alexandria University, El-Shatby, Alexandria 21545, Egypt.

ABSTRACT
This study focuses on the biological activities of eleven chitosan products with a viscosity-average molecular weight ranging from 22 to 846 kDa in combination with the most active monoterpenes (geraniol and thymol), out of 10 tested, against four plant pathogenic bacteria, Agrobacterium tumefaciens, Erwinia carotovora, Corynebacterium fascians, and Pseudomonas solanacearum. The antibacterial activity was evaluated in vitro by the agar dilution technique as a minimum inhibitory concentration (MIC) that was found to be dependent on the type of the microorganism tested. The most active product of chitosan was used for biofilm production enriched with geraniol and thymol (0.1 and 0.5%) and the films were also evaluated against the tested bacteria. The biological bioactivities summarized here may provide novel insights into the functions of chitosan and some monoterpenes and potentially allow their use for food protection from microbial attack.

No MeSH data available.


Related in: MedlinePlus

The in vitro inhibition of A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum on NA plates with chitosan films enriched with 0.1 and 0.5% geraniol or thymol. Plates were inoculated with 105–106 colony-forming units (CFU)/plate and incubated for 48 h at 37°C. The initial disc diameter was 10 mm, and the inside diameter of Petri dish was 50 mm. Ch: chitosan; G: geraniol; T: thymol.
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fig3: The in vitro inhibition of A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum on NA plates with chitosan films enriched with 0.1 and 0.5% geraniol or thymol. Plates were inoculated with 105–106 colony-forming units (CFU)/plate and incubated for 48 h at 37°C. The initial disc diameter was 10 mm, and the inside diameter of Petri dish was 50 mm. Ch: chitosan; G: geraniol; T: thymol.

Mentions: Antibacterial assay of Ch/starch films incorporated with geraniol or thymol (0.1 and 0.5%) was expressed by disk diffusion method on NA plates and the results are shown in Figure 3. The figure indicates that incorporation of thymol significantly increased the activity compared to geraniol at the same concentration. The inhibition zones obtained by film with geraniol (0.5%) were 6.67, 10.67, 7.67, and 9.33 mm for A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum, respectively. However, the inhibition zones caused by film with thymol (0.5%) were 12.33, 18.33, 14.33, and 16.00 mm for A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum, respectively. Photograph of the in vitro growth of A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum in NA plates incorporated with chitosan film enriched with thymol (0.5%) is also shown in Figure 4. Ch/starch film, without geraniol or thymol, served as a control to determine its potential antimicrobial effect, but we did not observe any inhibition of the tested bacteria by the control films (Figure 4). This result may refer to the fact that the inoculum in this experiment was 105–106 CFU, whereas other studies have used much lower inoculum (<102 CFU) for similar experiments [45, 46]. Thus, the high number of bacteria may exceed the inhibition activity of chitosan. Another explanation may be in the fact that chitosan must be dissolved to act as an antimicrobial agent. It is possible that chitosan molecules were tightly bound within the film, which prevented expression of the antimicrobial action. It can be also noted that the inhibition effects of geraniol and thymol incorporated into the chitosan films were lower than those of pure thymol with chitosan solutions (Table 1). The possible reason for the decreased activity of monoterpenes incorporated into the chitosan film could be due to partial loss potential of very volatile compounds during the preparation of the film. The other reason may be due to the leakage of controlled release of active compounds from the film during incubation period.


The Antibacterial Activity of Chitosan Products Blended with Monoterpenes and Their Biofilms against Plant Pathogenic Bacteria.

Badawy ME, Rabea EI, Taktak NE, El-Nouby MA - Scientifica (Cairo) (2016)

The in vitro inhibition of A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum on NA plates with chitosan films enriched with 0.1 and 0.5% geraniol or thymol. Plates were inoculated with 105–106 colony-forming units (CFU)/plate and incubated for 48 h at 37°C. The initial disc diameter was 10 mm, and the inside diameter of Petri dish was 50 mm. Ch: chitosan; G: geraniol; T: thymol.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4834403&req=5

fig3: The in vitro inhibition of A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum on NA plates with chitosan films enriched with 0.1 and 0.5% geraniol or thymol. Plates were inoculated with 105–106 colony-forming units (CFU)/plate and incubated for 48 h at 37°C. The initial disc diameter was 10 mm, and the inside diameter of Petri dish was 50 mm. Ch: chitosan; G: geraniol; T: thymol.
Mentions: Antibacterial assay of Ch/starch films incorporated with geraniol or thymol (0.1 and 0.5%) was expressed by disk diffusion method on NA plates and the results are shown in Figure 3. The figure indicates that incorporation of thymol significantly increased the activity compared to geraniol at the same concentration. The inhibition zones obtained by film with geraniol (0.5%) were 6.67, 10.67, 7.67, and 9.33 mm for A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum, respectively. However, the inhibition zones caused by film with thymol (0.5%) were 12.33, 18.33, 14.33, and 16.00 mm for A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum, respectively. Photograph of the in vitro growth of A. tumefaciens, C. fascians, E. carotovora, and P. solanacearum in NA plates incorporated with chitosan film enriched with thymol (0.5%) is also shown in Figure 4. Ch/starch film, without geraniol or thymol, served as a control to determine its potential antimicrobial effect, but we did not observe any inhibition of the tested bacteria by the control films (Figure 4). This result may refer to the fact that the inoculum in this experiment was 105–106 CFU, whereas other studies have used much lower inoculum (<102 CFU) for similar experiments [45, 46]. Thus, the high number of bacteria may exceed the inhibition activity of chitosan. Another explanation may be in the fact that chitosan must be dissolved to act as an antimicrobial agent. It is possible that chitosan molecules were tightly bound within the film, which prevented expression of the antimicrobial action. It can be also noted that the inhibition effects of geraniol and thymol incorporated into the chitosan films were lower than those of pure thymol with chitosan solutions (Table 1). The possible reason for the decreased activity of monoterpenes incorporated into the chitosan film could be due to partial loss potential of very volatile compounds during the preparation of the film. The other reason may be due to the leakage of controlled release of active compounds from the film during incubation period.

Bottom Line: The antibacterial activity was evaluated in vitro by the agar dilution technique as a minimum inhibitory concentration (MIC) that was found to be dependent on the type of the microorganism tested.The most active product of chitosan was used for biofilm production enriched with geraniol and thymol (0.1 and 0.5%) and the films were also evaluated against the tested bacteria.The biological bioactivities summarized here may provide novel insights into the functions of chitosan and some monoterpenes and potentially allow their use for food protection from microbial attack.

View Article: PubMed Central - PubMed

Affiliation: Department of Pesticide Chemistry and Technology, Faculty of Agriculture, Alexandria University, El-Shatby, Alexandria 21545, Egypt.

ABSTRACT
This study focuses on the biological activities of eleven chitosan products with a viscosity-average molecular weight ranging from 22 to 846 kDa in combination with the most active monoterpenes (geraniol and thymol), out of 10 tested, against four plant pathogenic bacteria, Agrobacterium tumefaciens, Erwinia carotovora, Corynebacterium fascians, and Pseudomonas solanacearum. The antibacterial activity was evaluated in vitro by the agar dilution technique as a minimum inhibitory concentration (MIC) that was found to be dependent on the type of the microorganism tested. The most active product of chitosan was used for biofilm production enriched with geraniol and thymol (0.1 and 0.5%) and the films were also evaluated against the tested bacteria. The biological bioactivities summarized here may provide novel insights into the functions of chitosan and some monoterpenes and potentially allow their use for food protection from microbial attack.

No MeSH data available.


Related in: MedlinePlus