Antibacterial Efficacy and Mechanism of Mannosylerythritol Lipids-A on Listeria monocytogenes.

Xiayu Liu,Xinglin Zhang,Xinxin Pang,Yansha Wu,Wanyi Zhou,Yajing Wu,Qin Shu,Qihe Chen,Jianrui Niu

doi:10.3390/molecules25204857

Xiayu Liu, Xinglin Zhang + Show 7 more

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https://doi.org/10.3390/molecules25204857

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Abstract

Mannosylerythritol lipids-A (MEL-A) is a novel biosurfactant with excellent surface activity and potential biomedical applications. In this study, we explored the antibacterial activity and the underlying mechanisms of MEL-A against the important food-borne pathogen Listeria monocytogenes. The bacterial growth and survival assays revealed a remarkable antibacterial activity of MEL-A. Since MEL-A is a biosurfactant, we examined the cell membrane integrity and morphological changes of MEL-A-treated bacteria by biochemical assays and flow cytometry analysis and electron microscopes. The results showed obvious damaging effects of MEL-A on the cell membrane and morphology. To further explore the antibacterial mechanism of MEL-A, a transcriptome analysis was performed, which identified 528 differentially expressed genes (DEGs). Gene ontology (GO) analysis revealed that the gene categories of membrane, localization and transport were enriched among the DEGs, and the analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways demonstrated significant changes in the maltodextrin ABC transporter system and stress response system. Furthermore, the growth of L. monocytogenes could also be significantly inhibited by MEL-A in milk, a model of a real food system, suggesting that MEL-A could be potentially applied as an natural antimicrobial agent to control food-borne pathogens in the food industry.

Highlights

Food safety is one of the most important public health issues in the world
We found that Mannosylerythritol lipids-A (MEL-A) has an excellent inhibitory effect on L. monocytogenes by causing damages on the cell membrane
1 mL of L. monocytogenes was inoculated into a 50 mL reagent bottle containing sterile brain–heart infusion (BHI) with different concentrations of Mannosylerythritol lipids (MELs)-A, and all the flasks were incubated in an orbital shaker (37 ◦ C, 180 rpm)

Summary

Introduction

Food safety is one of the most important public health issues in the world. With the continuous development of globalization, the factors affecting food safety are becoming more and more diverse and complicated, and the incidence of food-borne diseases is constantly increasing. An analysis by the World Health Organization (WHO) finds that approximate 600 million people are infected with food-borne diseases each year, which causes more than 420,000 deaths [1]. It is estimated that the real incidence of food-borne diseases is much higher than the reported incidence [2]. L. monocytogenes is a short rod-shaped Gram-positive bacterial and one of the most popular food-borne pathogens all over the world. In 1926, it was described for the first time in an outbreak which interfered with guinea pigs and rabbits [3] and recognized as a food-borne pathogen in 1980s [4]

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