The use of bacteria and/or their compounds is an alternative to the use of positive-list additives that the food industry is using as a tool to meet consumer demands for more natural, long-shelf-life, and healthy products, in short, to offer clean label foods. The aim of this study is to investigate the suitability of cell-free supernatants (CFSs) from Qualified Presumption of Safety strains as bioprotective cultures. Out of an initial screening panel of about 200 isolates, strains Pediococcus acidilactici CNTA 1059, Lactiplantibacillus plantarum CNTA 600, Levilactobacillus brevis CNTA 1374, and Bacillus subtilis CNTA 517 demonstrated strong antimicrobial activity against, especially, Gram-positive bacteria. The CFSs of these four strains showed minimum inhibitory concentration values between 0.15% and 5% against Listeria monocytogenes and Lentilactobacillus parabuchneri. None of the four selected strains exhibited acquired resistance to target antibiotics, and the non-toxigenicity of all the CFSs was demonstrated. In the case of the three lactic acid bacteria, the presence of bacteriocin-like inhibitory substances was confirmed following the decline in antimicrobial activity due to treatment with proteases. Regarding B. subtilis, biosynthetic gene clusters for different bacteriocin-like substances, including protease-resistant lipoproteins, were found via whole-genome sequencing. In addition, all of the CFSs exhibited stable antimicrobial activity at a wide range of temperatures (70–121 °C) used for the pasteurization and sterilization of food products, with a loss of antimicrobial activity ranging from 3% to 28%. These results point to the possibility that CFSs from these strains could be used in the food industry as a biocontrol tool to develop new products.

Probiotic strains with health-promoting activities have emerged as a promising strategy to prevent or treat different metabolic syndrome-related disturbances, including obesity or type 2 diabetes. In this work, we characterize the probiotic properties of a novel strain of Latilactobacillus sakei (L. sakei) CNTA 173, and we demonstrate its anti-obesity properties using the in vivo model Caenorhabditis elegans (C. elegans). This new strain exhibited sensitivity to the entire spectrum of antibiotics analysed, gastric and intestinal in vitro resistance, β-galactosidase activity, and the ability to form biofilm and to produce acetic acid in vitro. Cell culture analyses demonstrated that L. sakei CNTA 173 was able to reduce the adhesion to Caco-2 cells of the pathogenic E. coli O157:H7 and to exert immunomodulatory capacity in RAW 264.7 and HT-29 in vitro models. Furthermore, supplementation with L. sakei CNTA 173 counteracted the deleterious effects of glucose in C. elegans by significantly reducing fat accumulation, enhancing the oxidative stress response, and extending lifespan by directly regulating the carbohydrate and lipid metabolism-related genes acox-1, maoc-1, and daf-16. Our results unveil new strain-specific mechanisms of action by which L. sakei CNTA 173 exerts beneficial effects in vitro and in C. elegans, and suggest potential application of this novel probiotic strain in the prevention and treatment of metabolic syndrome-related disturbances.

The call for new approaches to prevent and treat metabolic syndrome-related diseases has led to research on the use of lacto-fermentative probiotics with beneficial metabolic properties like Lactobacilli. Here, we characterize the probiotic properties of a novel strain, Lactiplantibacillus plantarum CNTA 628, and investigate its potential anti-obesity and health-promoting activities in the Caenorhabditis elegans model, additionally elucidating the molecular mechanisms involved. Lactiplantibacillus plantarum CNTA 628 exhibited sensitivity to the entire spectrum of antibiotics analyzed, gastric and intestinal resistance in vitro, β-galactosidase and bile-salt hydrolysate activities, and the capacity to form biofilms and produce SCFAs. In addition, it reduced the binding of the pathogenic E. coli O157:H7 to intestinal epithelial cells (Caco-2) and exerted immune-modulating effects in cellular models. Supplementation with this probiotic significantly reduced C. elegans fat accumulation by more than 18% under control and high-glucose conditions, lowered senescence, improved oxidative stress, and significantly enhanced lifespan without affecting the development of the worms. Gene expression analyses evidenced that L. plantarum CNTA 628 plays a role in regulating daf-22 and maoc-1 gene expression, both linked to beta-oxidation pathways. Our results demonstrate the health-benefiting properties of this novel strain and suggest its potential as probiotic candidate for the prevention and treatment of metabolic syndrome-related conditions.

Leishmaniasis is a parasitic disease caused by Leishmania spp., transmitted by sandflies, and endemic in 98 countries. Leishmania infantum, the main agent of visceral leishmaniasis in Europe, commonly infects both humans and animals, with dogs as the principal domestic reservoir. Clinical manifestations in dogs depend on the host immune response. A robust Th1 response facilitates macrophage activation and parasite control, while persistently elevated TNF-α and IL-6 can lead to chronic inflammation and tissue damage. Current treatments reduce parasite load but rarely achieve complete cure and are often associated with relapses and resistance. Artemisia annua, source of artemisinin, could be a promising alternative to canine leishmaniasis. Despite its potential, no published studies have investigated its effect specifically against Leishmania infantum as well as its possible dual action: antiparasitic and immunomodulation. We conducted in vitro evaluations of a standardized Artemisia annua extract. Leishmanicidal activity was assessed against both promastigote and amastigote stages, and cytokine modulation was evaluated in RAW 264.7 macrophages. The extract showed strong leishmanicidal activity without cytotoxicity and significantly reduced TNF-α and IL-6 levels under inflammatory conditions, and in both cases, efficiency was correlated with artemisinin content. These results support Artemisia annua as a promising safer therapeutic adjuvant candidate for canine leishmaniasis, targeting both the parasite and the host inflammatory response.

Introduction: In the last few years, several studies have described the beneficial effects of the supplementation of diets with certain probiotic strains and different obesity-related disturbances, including metabolic syndrome. New research lines aim to characterize and understand the strain-specific mechanisms of action and their effects on the host’s health. The use of animal models is necessary to understand how probiotics interact with the gut microbiota and exert beneficial activities, which would allow us gain insight into potential new strategies against obesity-related diseases. Objective: we aim to characterize the effects of a novel probiotic strain of Latilactobacillus sakei (L. sakei) in two different animal models with adiposity excess. Methods: Caenorhabditis elegans was used as a starting in vivo model to analyse how the probiotics affect fat accumulation, oxidative stress, senescence, and lifespan when exposed to high-glucose conditions. Then, the effects of L. sakei oral administration (10⁹ CFU/day) were evaluated in diet-induced obese (DIO) Wistar rats, and biochemical, transcriptomic, metagenomics, and metabolomics analyses were performed. Results: Supplementation with L. sakei in C. elegans counteracted the deleterious effects of glucose by reducing fat accumulation, enhancing the oxidative stress response, and extending lifespan by directly regulating the carbohydrate- and lipid metabolism-related genes acox-1, maoc-1, and daf-16. Following the same trend, DIO rats supplemented with L. sakei showed lower proportions of mesenteric and subcutaneous fat, improved glucose tolerance, and an ameliorated inflammatory marker profile, partly by regulating the expression levels of key metabolic genes like adiponectin, leptin, and Acox1. The oral administration of L. sakei modulated faecal microbiota composition and induced the production of novel plasma metabolites. Conclusions: our results unveil new strain-specific mechanisms of action through which L. sakei exerts health-promoting effects in C. elegans and DIO adiposity models, as well as further describe how these probiotics could potentially be useful for the prevention and treatment of metabolic syndrome-related diseases.