Draft Genome Sequence of Probiotic Enterococcus faecium Strain L-3

Evaluation of the Efficacy of Enterococcus faecium L3 as a Feed Probiotic Additive in Chicken

The study was devoted to the comparison of the probiotic effect of enterococcal Enterococcus faecium L3 to the antibiotic enramycin as a chicken feed additive. Two hundred and sixteen chickens were divided into three groups and tested by different parameters including weight gain, food consumption, blood biochemistry, immunology, and caecal microbiome at two checkpoints, 21 and 39 days after birth. By the end of the experiment, a group of chickens getting probiotic demonstrated weight gain of more than 100 g at the average relative to the control group with no additive in animal feed (P < 0.05). Blood serum biochemistry showed a significant increase in HDL level (P < 0.05) relative to the control group. The 16S RNA sequencing demonstrated the growth abundance of Lachnospiraceae and the decrease of Proteobacteria in probiotic fed group. On the contrary, the antibiotic fed group showed a noticeable increase in the abundance of Proteobacteria which included the genus Salmonella. Thus, probiotic E. faecium L3 being added to chicken food as a single additive may be considered as a possible replacement of antibiotic enramycin.

Developing a Live Probiotic Vaccine Based on the Enterococcus faecium L3 Strain Expressing Influenza Neuraminidase

Probiotic microorganisms are currently considered as a promising platform for the development of recombinant vaccines expressing foreign antigens. In this study, we generated and evaluated the live mucosal recombinant vaccine by integrating genes encoding influenza virus neuraminidase (NA) of the N2 subtype into the DNA of the probiotic strain Enterococcus faecium L3 (L3). We confirmed NA expression in the pili of L3 using immune electron microscopy. Mice were fed with a probiotic vaccine containing the NA gene (L3-NA) or pure L3. Oral administration of L3-NA caused detectable increase in virus-specific serum IgG and local IgA after the third feeding. Immunization with L3-NA increased the survival rate by 34% when the mice were infected using A(H1N1)pdm09 influenza virus after the third feeding. After S. pneumoniae post-influenza infection, the L3-NA-immunized mice were 50% more protected from lethality in comparison with L3-fed mice. Thus, a live probiotic vaccine candidate based on L3 induced the formation of systemic and local immunity and provide partial protection against complicated influenza.

Anti-Influenza Activity of Enterocin B In vitro and Protective Effect of Bacteriocinogenic Enterococcal Probiotic Strain on Influenza Infection in Mouse Model

In spite of scientific evidence demonstrating the antiviral activity of lactic-acids bacteria, little is known about the mechanism of their action. Previously, several bacteriocins isolated from lactic acid bacteria (LAB) and some other microorganisms were reported as having antiviral activity in vitro. In the present study, chemically synthetized enterocin B (EntB) and the strain E. faecium L3, known as the producer of this peptide, were tested for activity against influenza viruses. The inhibition of cytopathic effect of А/Perth/16/2009(H3N2) and A/South Africa/3626/2013(H1N1) pdm influenza viruses in MDCK cells by chemically synthetized EntB was revealed. The EntB demonstrated antiviral activity at a concentration of 2.5-5 μg/ml depending on the dose of viruses. This peptide exhibited low toxicity in MDCK cells, causing partial damage of the monolayer of the cells only at a concentration above 10 μg/ml. It was also shown, that strain E. faecium L3-protected mice from lethal A/South Africa/3626/2013(H1N1) pdm infection. We speculate that this protective effect of enterococci may be associated with the specific action of enterocin B, which possesses antiviral activity in vitro.

Draft genome sequence of Enterococcus faecium SP15, a potential probiotic strain isolated from spring water

Objectives

Enterococci are Gram-positive lactic acid bacteria and common inhabitants of the gastrointestinal tract of mammals, including humans. They are also widely distributed in diverse environments such as soil, water, vegetables and food. Enterococcus faecium is able to produce antimicrobial compounds (enterocins) and thus can act as a probiotic. E. faecium SP15 is a newly identified enterocin-producing strain from spring water that has been subjected to genome sequence analysis to provide understanding of its antimicrobial and probiotic properties.

Data description

The draft genome of E. faecium SP15 comprises of 2,783,033 bp with a G+C content of 38.08%. Five genetic loci predicted to specify enterocin production were identified, but no virulence factors could be detected and only two potential antibiotic resistance genes were noted.

A genomic view of food-related and probiotic Enterococcus strains

The study of enterococcal genomes has grown considerably in recent years. While special attention is paid to comparative genomic analysis among clinical relevant isolates, in this study we performed an exhaustive comparative analysis of enterococcal genomes of food origin and/or with potential to be used as probiotics. Beyond common genetic features, we especially aimed to identify those that are specific to enterococcal strains isolated from a certain food-related source as well as features present in a species-specific manner. Thus, the genome sequences of 25 Enterococcus strains, from 7 different species, were examined and compared. Their phylogenetic relationship was reconstructed based on orthologous proteins and whole genomes. Likewise, markers associated with a successful colonization (bacteriocin genes and genomic islands) and genome plasticity (phages and clustered regularly interspaced short palindromic repeats) were investigated for lifestyle specific genetic features. At the same time, a search for antibiotic resistance genes was carried out, since they are of big concern in the food industry. Finally, it was possible to locate 1617 FIGfam families as a core proteome universally present among the genera and to determine that most of the accessory genes code for hypothetical proteins, providing reasonable hints to support their functional characterization.