Abbreviations: AAI, pairwise amino acid identity; ANI, average nucleotide identity; cAAI, pairwise amino acid identity of conserved genes. †These authors also contributed equally to this work †These authors share senior authorship. Six supplementary tables and seven supplementary figures are available with the online version of this article.

Enterococci belong to the lactic acid bacteria (LAB) and they are of importance in foods due to their involvement in food spoilage and fermentations, as well as their utilisation as probiotics in humans and slaughter animals. However, they are also important nosocomial pathogens that cause bacteraemia, endocarditis and other infections. Some strains are resistant to many antibiotics and possess virulence factors such as adhesins, invasins, pili and haemolysin. The role of enterococci in disease has raised questions on their safety for use in foods or as probiotics. Studies on the incidence of virulence traits among enterococcal strains isolated from food showed that some can harbour virulence traits, but it is also thought that virulence is not the result of the presence of specific virulence determinants alone, but is rather a more intricate process. Specific genetic lineages of hospital-adapted strains have emerged, such as E. faecium clonal complex (CC) 17 and E. faecalis CC2, CC9, CC28 and CC40, which are high risk enterococcal clonal complexes. These are characterised by the presence of antibiotic resistance determinants and/or virulence factors, often located on pathogenicity islands or plasmids. Mobile genetic elements thus are considered to play a major role in the establishment of problematic lineages. Although enterococci occur in high numbers in certain types of fermented cheeses and sausages, they are not deliberately added as starter cultures. Some E. faecium and E. faecalis strains are used as probiotics and are ingested in high numbers, generally in the form of pharmaceutical preparations. Such probiotics are administered to treat diarrhoea, antibiotic-associated diarrhoea or irritable bowel syndrome, to lower cholesterol levels or to improve host immunity. In animals, enterococcal probiotics are mainly used to treat or prevent diarrhoea, for immune stimulation or to improve growth. From a food microbiological point of view, the safety of the bacteria used as probiotics must be assured, and data on the major strains in use so far indicate that they are safe. The advantage of use of probiotics in slaughter animals, from a food microbiological point of view, lies in the reduction of zoonotic pathogens in the gastrointestinal tract of animals which prevents the transmission of these pathogens via food. The use of enterococcal probiotics should, in view of the development of problematic lineages and the potential for gene transfer in the gastrointestinal tract of both humans and animals, be carefully monitored, and the advantages of using these and new strains should be considered in a well contemplated risk/benefit analysis.

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Members of the genus Bacillus are known to produce a wide arsenal of antimicrobial substances, including peptide and lipopeptide antibiotics, and bacteriocins. Many of the Bacillus bacteriocins belong to the lantibiotics, a category of post-translationally modified peptides widely disseminated among different bacterial clades. Lantibiotics are among the best-characterized antimicrobial peptides at the levels of peptide structure, genetic determinants and biosynthesis mechanisms. Members of the genus Bacillus also produce many other nonmodified bacteriocins, some of which resemble the pediocin-like bacteriocins of the lactic acid bacteria (LAB), while others show completely novel peptide sequences. Bacillus bacteriocins are increasingly becoming more important due to their sometimes broader spectra of inhibition (as compared with most LAB bacteriocins), which may include Gram-negative bacteria, yeasts or fungi, in addition to Gram-positive species, some of which are known to be pathogenic to humans and/or animals. The present review provides a general overview of Bacillus bacteriocins, including primary structure, biochemical and genetic characterization, classification and potential applications in food preservation as natural preservatives and in human and animal health as alternatives to conventional antibiotics. Furthermore, it addresses their environmental applications, such as bioprotection against the pre- and post-harvest decay of vegetables, or as plant growth promoters.

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trans-Resveratrol metabolism by human gut microbiota shows pronounced interindividual differences, which should be taken into account during investigation of health-related effects of this stilbene. This trial was registered at the German Clinical Trials Register as DRKS00004311, Universal Trial Number (WHO) UTN: U1111-1133-4621.

The incidence of virulence factors among 48 Enterococcus faecium and 47 Enterococcus faecalis strains from foods and their antibiotic susceptibility were investigated. No strain was resistant to all antibiotics, and for some strains, multiple resistances were observed. Of E. faecium strains, 10.4% were positive for one or more virulence determinants, compared to 78.7% of E. faecalis strains. Strains exhibiting virulence traits were not necessarily positive for all traits; thus, the incidence of virulence factors may be considered to be strain specific.Enterococci constitute a major component of the microflora of artisanal cheeses produced in southern Europe (10) and are considered to play an important role in ripening and aroma development (1,5,28). This has led to the suggestion that enterococci be included in starter culture preparations for the manufacture of certain Mediterranean cheeses (1,5,23). However, enterococci are also major nosocomial pathogens causing a variety of infections (19,20). Enterococcus faecalis strains clearly dominate among enterococci isolated from human infections, while Enterococcus faecium strains are associated with the majority of the remainder (15).A specific cause for concern and contributing factor to pathogenesis of enterococci is their resistance to a wide variety of antibiotics (18,20). However, antibiotic resistance as such cannot explain the virulence of enterococci. Although enterococci possess subtle virulence traits (25), considerable progress has recently been made in determining these. For example, studies have shown that phenotypes such as ␤-hemolysin/bacteriocin (also called cytolysin) and aggregation substance (AS), which are encoded by E. faecalis pheromone-responsive plasmids, are related to pathogenicity and enhance the virulence of enterococci in animal models (2,12,14,15,26). AS is an adhesin which mediates the formation of cell clumps that allow the highly efficient transfer of the sex pheromone plasmid on which AS is encoded (4). An interesting variation in the generally similar AS (about 90% homology) encoded by sex pheromone plasmids such as pAD1, pCF10, and pPD1 is encoded by asa373 on plasmid pAM373. This AS is also involved in a clumping response, but it has little homology to the "classical" AS and therefore represents a rather unique type of adhesin (22). Other virulence factors include the adhesin called enterococcal surface protein (Esp) and gelatinase (Gel), which is an extracellular metalloendopeptidase (26).This study aimed to determine the incidence of hemolysin; classical AS; and the aggregation substances Asa373, Gel, and Esp and antibiotic susceptibility among enterococci isolated mostly from cheeses. Studies formed part of the European Union (EU) project FAIR-CT97-3078, "Enterococci in Food Fermentations: Functional and Safety Aspects." As E. faecalis and E. faecium are predominantly associated with human infection and as these species were also predominant among strains isolated from cheese in the EU study, our study was concerned only with...

Enterococci are lactic acid bacteria of importance in food, public health and medical microbiology. Many strains produce bacteriocins, some of which have been well characterized. This review describes the structural and genetic characteristics of enterocins, the bacteriocins produced by enterococci. Some of these can be grouped with typical bacteriocins produced by lactic acid bacteria according to traditional classification, whereas others are atypical and structurally distinct from the general classes of bacteriocins. These atypical enterocins recently played an important role in and prompted reclassification of the class II bacteriocins into a new scheme. In this review, a more simplified classification scheme for enterocins based on amino acid sequence homologies is proposed. Enterocins are of interest for their diversity and potential for use as food biopreservatives. The emergence of multiple antibiotic-resistant enterococci among agents of nosocomial disease and the presence of virulence factors among food isolates requires a careful safety evaluation of isolates intended for potential biotechnical use. Nevertheless, enterococcal bacteriocins produced by heterologous hosts or added as cell-free preparations may still be attractive for application in food preservation.