Evaluation of Probiotic Properties and Safety of Enterococcus faecium Isolated From Artisanal Tunisian Meat "Dried Ossban".

Mohamed Zommiti,Mélyssa Cambronel,Nathalie Connil,Olivier Maillot,Magalie Barreau,Mounir Ferchichi,Khaled Sebei,Marc Feuilloley

doi:10.3389/fmicb.2018.01685

Abstract

Enterococcus faecium strains were isolated from an original biotope, artisanal dried Tunisian meat “Dried Ossban,” and evaluated for safety and capacity as probiotics. Gram-positive, catalase negative, and bacteriocin-producing bacteria were screened using selective microbiological media. All isolates were identified by phenotypic and molecular tools. Five E. faecium strains (MZF1, MZF2, MZF3, MZF4, and MZF5) were selected and further assessed for their probiotic properties. They were found to be resistant to the physiological concentrations of bile salts, and the harsh conditions of the gastrointestinal tract, and showed autoaggregation and adhesion ability. All these isolates possess at least one enterocin and could efficiently inhibit the growth of Listeria innocua HPB13. The analysis of their safety profile revealed for almost all the strains the absence of cytotoxicity and virulence determinants, and susceptibility to clinically important antibiotics such as vancomycin. These data suggest that these bacteria, isolated from “Dried Ossban,” do not present a risk to human health, and may be considered as interesting candidates for future use as probiotics and bioprotective cultures for application in the food and/or feed industries.

Highlights

Enterococci are ubiquitous microorganisms, widespread in the environment
A dendrogram was created according to the distance level between the E. faecium strains isolated from Tunisian “Dried Ossban” (Figure 1A) and with the E. faecium reference strains available in the Biotyper library (Figure 1B)
This phyloproteomic analysis shows the hierarchical relationship between the five isolates and suggests that E. faecium MZF5 is more distant from the four other “Dried Ossban” strains

Summary

Introduction

Enterococci are ubiquitous microorganisms, widespread in the environment. they represent the common members of the commensal microbiota in the intestine of humans, mammals, and other animals encompassing reptiles, birds, and insects, but they are found in other complex ecosystems such as soil, plants, water, waste, food, and feed (Foulquié Moreno et al, 2006; Byappanahalli et al, 2012). Enterococcus species are widely present in traditional fermented foods (Giraffa, 2003) due to their amazing capacity to withstand extreme temperature (Murray, 1990), high salinity, and pH levels (Franz et al, 2011). They can grow in the presence of 40% (w/v) bile salts (Fisher and Phillips, 2009). These special characteristics of adaptability to various matrices and conditions may allow these bacteria to cause spoilage of a wide range of food products, meat and its derivatives (Björkroth et al, 2005).

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Conclusion