The Genus Enterococcus: Between Probiotic Potential and Safety Concerns-An Update.

Hasna Hanchi,Walid Mottawea,Riadh Hammami,Khaled Sebei

doi:10.3389/fmicb.2018.01791

Hasna Hanchi, Walid Mottawea + Show 2 more

Open Access

https://doi.org/10.3389/fmicb.2018.01791

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Abstract

A considerable number of strains belonging to different species of Enterococcus are highly competitive due to their resistance to wide range of pH and temperature. Their competitiveness is also owed to their ability to produce bacteriocins recognized for their wide-range effectiveness on pathogenic and spoilage bacteria. Enterococcal bacteriocins have attracted great research interest as natural antimicrobial agents in the food industry, and as a potential drug candidate for replacing antibiotics in order to treat multiple drugs resistance pathogens. However, the prevalence of virulence factors and antibiotic-resistance genes and the ability to cause disease could compromise their application in food, human and animal health. From the current regulatory point of view, the genus Enterococcus is neither recommended for the QPS list nor have GRAS status. Although recent advances in molecular biology and the recommended methods for the safety evaluation of Enterococcus strains allowed the distinction between commensal and clinical clades, development of highly adapted methods and legislations are still required. In the present review, we evaluate some aspects of Enterococcus spp. related to their probiotic properties and safety concerns as well as the current and potential application in food systems and treatment of infections. The regulatory status of commensal Enterococcus candidates for food, feed, probiotic use, and recommended methods to assess and ensure their safety are also discussed.

Highlights

Enterococci are lactic acid bacteria (LAB) comprising both pathogenic and commensal microorganisms ubiquitous in environment even as gut symbionts
The genus Enterococcus has not yet obtained the status generally recognized as safe (GRAS) (Huys et al, 2013), but some members are used as probiotics and in production of feed additives to prevent diarrhea or to improve growth in animals (Franz et al, 2011)
In order to identify new members, other microorganisms with probiotic potential should be evaluated for probiotic candidacy

Summary

INTRODUCTION

Enterococci are lactic acid bacteria (LAB) comprising both pathogenic and commensal microorganisms ubiquitous in environment even as gut symbionts. Further evidences are required, the advances outlined above support the call for new recommendations about probiotic legislative framework in order to distinguish between safe and potentially harmful Enterococcus strains Organizations such as the EFSA, the Advisory Committee on Novel Foods and Processes, ACNFP, and the Food Standards Agency permitted the use of certain strains of enterococci as a food additive and supplements based on a careful case-by-case assessment. Over recent years, purified and identified enterococci bacteriocins were added to foods in the form of concentrated preparations or produced in situ by bacteriocinogenic starter, adjunct or protective cultures (Arqués et al, 2015) These bacteriocins are being considered as promising drug candidates for replacing antibiotics to treat multiple drugs resistant pathogens and maintain human health (Hammami et al, 2013). E. faecium and E. faecalis are TABLE 1 | Recommended methods for the safety assessment of Enterococcus (non-QPS species)

Methods

Alternative methods:

CONCLUSIONS AND PERSPECTIVES