Document Type : scientific research article
Authors
1
Dep. of Fishery Products Processing, Faculty of Fisheries and Environmental Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Iran – Member of the Research Institute for Development of Marine Based Economy, Gorgan Universi
2
Ph.D. Graduate in Fishery Products Processing, Faculty of Fisheries and Environmental Sciences, Gorgan University of Agricultural Sciences and Natural Resources
Abstract
Background and Objective: One of the new theories is the control of microorganisms using a self-control mechanism, which is carried out through bacterial signaling metabolites via the quorum sensing process. The aim of this study was to produce nanocapsules containing bacterial supernatant capable of controlled release according to environmental needs to manage bacterial contamination.
Materials and Methods: according to the results, nanocapsules containing the specific supernatant of lactic acid bacteria, produced during the logarithmic growth phase and the death phase, were prepared. The inhibitory properties of these substances against Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Bacillus cereus were evaluated using the MIC method. Eventually, the most effective encapsulated supernatant composition was selected against the target bacteria. The expression of a specific virulence gene in L. monocytogenes was assessed using real-time PCR. Various characteristics of the nanocapsules, including structure, stability, encapsulation efficiency, and other relevant parameters, were examined. The obtained data were statistically analyzed using SPSS software.
Results: The results showed that the supernatant from lactic acid bacteria in the death phase had the greatest inhibitory effect on the growth of E. coli, S. aureus, Bacillus cereus, and L. monocytogenes (P < 0.05). Additionally, the duration of effectiveness of the encapsulated supernatant was significantly longer than that of the non-encapsulated supernatant. Gene expression analysis of L. monocytogenes revealed that the virulence gene hly was significantly reduced under these conditions but was still expressed.
Conclusion: From the obtained results, it can be concluded that the bacterial supernatant contains metabolites capable of controlling microbial growth and reducing it. However, it does not have an effect on controlling the expression of bacterial virulence genes.
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