Genetic and Biochemical Evidence That Enterococcus faecalis Gr17 Produces a Novel and Sec-Dependent Bacteriocin, Enterocin Gr17

Bacteriocins are ribosomally synthesized antibacterial peptides or proteins from microorganisms. We report a novel bacteriocin producing strain, Enterococcus faecalis Gr17, that was isolated from the Chinese traditional low-salt fermented whole fish product Suan yu. E. faecalis Gr17 displayed potent antibacterial activity against foodborne pathogenic and spoilage bacteria. The complete genome of E. faecalis Gr17 contained one circular chromosome and plasmid. The gene cluster of a novel bacteriocin designated enterocin Gr17 was identified. The enterocin Gr17 structural gene encodes a precursor of the bacteriocin. Two other transporter genes and an immunity gene within two divergent operons were identified as being associated with enterocin Gr17 secretion and protection. The novel enterocin Gr17 was purified by ammonium sulfate precipitation, cation exchange, gel filtration, and reverse-phase high-performance liquid chromatography. The molecular weight of enterocin Gr17 was 4,531.01 Da as determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and its mature amino acid sequence of enterocin Gr17 was RSYGNGVYCNNSKCWVNWGEAKENIIGIVISGWATGLAGMGR. Sequence alignment revealed that enterocin Gr17 is a class IIa bacteriocin with similarities to enterocin P. The merits of bactericidal activity, sensitivity to enzymes, and pronounced stability to chemicals, temperature (60°C, 30 min and 121°C, 15 min), and pH (2-10) indicated practicality and safety of enterocin Gr17 in the food industry. The complete genome information of E. faecalis Gr17 will improve the understanding of the biosynthetic mechanism of enterocin Gr17, which has potential value as a food biopreservative.

Pilot evaluation of Enterococcus faecium SF68 as adjunctive therapy for oclacitinib-responsive adult atopic dermatitis in dogs

OBJECTIVE

To evaluate the adjunctive effect of supplementation with Enterococcus faecium SF68 (FortiFlora; Purina Pro Plan Veterinary Diets) on oclacitinib (Apoquel, Zoetis) dose reduction, while maintaining or reducing the Pruritus Visual Analog Score and Canine Atopic Dermatitis Extent and Severity Index values in client-owned adult dogs with environmental atopic dermatitis.

MATERIALS AND METHODS

Enrolled dogs had exhibited control of atopic dermatitis on oclacitinib for at least 6 months before, and continuing throughout, the study. Dogs with non-seasonal pruritus were blindly randomised to receive either SF68 (1×10⁸ colony forming units/g orally twice daily) or placebo for 12 weeks. After 8 weeks of supplementation, oclacitinib dose was decreased by approximately 25%, aiming to maintain and reduce the clinical disease scores.

RESULTS

Supplementation with SF68 was associated with no difference in oclacitinib dose reduction versus placebo in 21 client-owned dogs with atopic dermatitis. Clinical disease scores were not different between groups at study completion.

CLINICAL SIGNIFICANCE

Further larger-scale studies are warranted to investigate optimal strain(s), dosing and duration of probiotic supplementation as an adjunctive strategy in management of canine atopic dermatitis.

Enterococci: Between Emerging Pathogens and Potential Probiotics

Enterococci are ubiquitous microorganisms that could be found everywhere; in water, plant, soil, foods, and gastrointestinal tract of humans and animals. They were previously used as starters in food fermentation due to their biotechnological traits (enzymatic and proteolytic activities) or protective cultures in food biopreservation due to their produced antimicrobial bacteriocins called enterocins or as probiotics, live cells with different beneficial characteristics such as stimulation of immunity, anti-inflammatory activity, hypocholesterolemic effect, and prevention/treatment of some diseases. However, in the last years, the use of enterococci in foods or as probiotics caused an important debate because of their opportunistic pathogenicity implicated in several nosocomial infections due to virulence factors and antibiotic resistance, particularly the emergence of vancomycin-resistant enterococci. These virulence traits of some enterococci are associated with genetic transfer mechanisms. Therefore, the development of new enterococcal probiotics needs a strict assessment with regard to safety aspects for selecting the truly harmless enterococcal strains for safe applications. This review tries to give some data of the different points of view about this question.

Toward rational selection criteria for selection of probiotics in pigs

An accurate understanding of properties of probiotics is a prerequisite for selecting probiotic organisms for use in swine production. This review aims to review selection criteria for probiotic organism in swine. The systematically investigated ecological history rather than the source of isolates should be regarded as the natural origin of probiotic strains, which helps to correct the inconsistencies arising from incorrect identification of the source. Moreover, in vivo studies are suggested as follow-up assessment to validate the characteristics of probiotic predicted by in vitro experiments. In addition, the intended probiotic effect depends on the age of the animal and disease prevention in young animals may require different probiotic strains when compared to growth promotion in older animals. With adequate selection criteria, the inclusion of probiotic in feed supplementation is a promising way to exert positive effects on sows, newborns, weanling animals and grower-finisher pigs. Both host-adapted probiotics and nomadic probiotics can be applied for pathogen inhibition but host adapted organisms appear to have a different mode of action. Host-adapted probiotic strains are likely to be associated with exclusive colonization while the nomadic or environmental strain exert better immune stimulating functions. Strains with potent enzymatic activity are fitter for grower pigs favoring feed digestion and enhancing growth performance.

Occurrence and Dynamism of Lactic Acid Bacteria in Distinct Ecological Niches: A Multifaceted Functional Health Perspective

Lactic acid bacteria (LAB) are representative members of multiple ecosystems on earth, displaying dynamic interactions within animal and plant kingdoms in respect with other microbes. This highly heterogeneous phylogenetic group has coevolved with plants, invertebrates, and vertebrates, establishing either mutualism, symbiosis, commensalism, or even parasitism-like behavior with their hosts. Depending on their location and environment conditions, LAB can be dominant or sometimes in minority within ecosystems. Whatever their origins and relative abundance in specific anatomic sites, LAB exhibit multifaceted ecological and functional properties. While some resident LAB permanently inhabit distinct animal mucosal cavities, others are provided by food and may transiently occupy the gastrointestinal tract. It is admitted that the overall gut microbiome has a deep impact on health and diseases. Here, we examined the presence and the physiological role of LAB in the healthy human and several animal microbiome. Moreover, we also highlighted some dysbiotic states and related consequences for health, considering both the resident and the so-called "transionts" microorganisms. Whether LAB-related health effects act collectively or follow a strain-specificity dogma is also addressed. Besides the highly suggested contribution of LAB to interplay with immune, metabolic, and even brain-axis regulation, the possible involvement of LAB in xenobiotic detoxification processes and metal equilibrium is also tackled. Recent technological developments such as functional metagenomics, metabolomics, high-content screening and design in vitro and in vivo experimental models now open new horizons for LAB as markers applied for disease diagnosis, susceptibility, and follow-up. Moreover, identification of general and more specific molecular mechanisms based on antioxidant, antimicrobial, anti-inflammatory, and detoxifying properties of LAB currently extends their selection and promising use, either as probiotics, in traditional and functional foods, for dedicated treatments and mostly for maintenance of normobiosis and homeostasis.