Abstract
Plantaricin Q7 is a broad-spectrum antimicrobial peptide produced by Lactobacillus plantarum Q7. The effects of plantaricin Q7 on Listeria monocytogenes and its biofilm were investigated. The results showed that plantaricin Q7 changed the cell membrane permeability and integrity of Listeria monocytogenes significantly. The extracellular lactate dehydrogenase activity increased from 156.74 U/L to 497.62 U/L, and the K+ concentration was increased rapidly from 0.02 g/L to 0.09 g/L. Furthermore, the flagellum motility of Listeria monocytogenes reduced and the relative adhesion rate decreased about 30% after treatment with plantaricin Q7. Meanwhile, the morphology and structure of Listeria monocytogenes cell and biofilm were damaged. These findings suggested that plantaricin Q7 exhibited significant inhibitory effects on not only Listeria monocytogenes cell but also its biofilm, which might be used as a natural and effective biological preservative for food storage.
Highlights
The attention of food safety has raised since the improvement of people’s living standards and the enhancement of health awareness
The diameter of inhibition zone measured by Oxford cup method was about 25.70 mm, and the titer of plantaricin Q7 against L. monocytogenes strains calculated by two-fold dilution method was 400 AU/mL, which suggested that the diameter of inhibition zone was larger than that of other bacteriocins under the same concentration conditions [22,31]
During the logarithmic growth period, L. monocytogenes grew rapidly without the addition of plantaricin Q7, while the growth trend was inhibited after treated with plantaricin Q7
Summary
The attention of food safety has raised since the improvement of people’s living standards and the enhancement of health awareness. Among all kinds of food safety incidents, food poisoning caused by microbial contamination accounts for the highest proportion. The World Health Organization (WHO) estimated that 70% of food-borne illness were caused by food and drinking water contaminated with disease-causing microorganisms [1]. In the microbial risk management system, the monitoring of biological hazards in food and the detection of common pathogenic bacteria had been listed as important aspects [2,3]. As a serious pathogenic bacteria, widely exists in water, soil and food, which could cause pregnancy abortion, sepsis, meningitis and encephalitis, as well as some diarrhea, skin infection [4]. The incidence of L. monocytogenes contamination is not high, its mortality rate (20~30%) is much higher than that of other common foodborne pathogens [5]. There are urgent demands for the discovery of new antimicrobial strategy against L. monocytogenes
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