Lactic acid bacteria (LAB) synthesize exopolysaccharides (EPS), which are structurally diverse biopolymers with a broad range of technological properties and bioactivities. There is scientific evidence that these polymers have health-promoting properties. Most commercialized probiotic microorganisms for consumption by humans and farmed animals are LAB and some of them are EPS-producers indicating that some of their beneficial properties could be due to these polymers. Probiotic LAB are currently used to improve human health and for the prevention and treatment of specific pathologic conditions. They are also used in food-producing animal husbandry, mainly due to their abilities to promote growth and inhibit pathogens via different mechanisms, among which the production of EPS could be involved. Thus, the aim of this review is to discuss the current knowledge of the characteristics, usage and biological role of EPS from LAB, as well as their postbiotic action in humans and animals, and to predict the future contribution that they could have on the diet of food animals to improve productivity, animal health status and impact on public health.

Recently, the interest of consumers regarding artisan cheeses worldwide has increased. The ability of different autochthonous and characterized lactic acid bacteria (LAB) to produce aromas and the identification of the volatile organic compounds (VOCs) responsible for flavor in cheeses are important aspects to consider when selecting strains with optimal aromatic properties, resulting in the diversification of cheese products. The objective of this work is to determine the relationship between VOCs and microorganisms isolated (Lacticaseibacillus paracasei, Lactiplantibacillus plantarum, Leuconostoc mesenteroides and Lactococcus lactis subsp. hordniae) from raw sheep milk cheeses (matured and creamy natural) using accuracy and alternative methods. On combining Sanger sequencing for LAB identification with Gas Chromatography coupled to Ion Mobility Spectrometry (GC–IMS) to determinate VOCs, we describe cheeses and differentiate the potential role of each microorganism in their volatilome. The contribution of each LAB can be described according to their different VOC profile. Differences between LAB behavior in each cheese are shown, especially between LAB involved in creamy cheeses. Only L. lactis subsp. hordniae and L. mesenteroides show the same VOC profile in de Man Rogosa and Sharpe (MRS) cultures, but for different cheeses, and show two differences in VOC production in skim milk cultures. The occurrence of Lactococcus lactis subsp. hordniae from cheese is reported for first time.

The reformulation of meat products is a pending task for the scientific-technological sector. Fermented meat products can carry probiotics, and studying their effect during the product shelf life currently represents a large area of vacancy. The objective of this work was to study the viability of microencapsulated (E) and unencapsulated (P) Lactiplantibacillus plantarum BFL as well as their effects on the microbiological and physicochemical parameters of fermented sausages preserved at 20 °C and 5 °C during 60 days of storage. The inoculated sausages (P and E) had significantly reduced pH values and potential pathogenic microorganism counts. The viability of encapsulated L. plantarum BFL (E) did not decline during storage as it did in its unencapsulated state (P). In addition, L. plantarum BFL could present an antioxidant effect at 20 °C towards the end of storage. The probiotic L. plantarum BFL generally tolerated the meat matrix conditions; it could be used as a biocontroller since its high viability rates would allow it to be projected as an adjunct culture for the meat industry. However, spray-drying microencapsulation of the probiotic L. plantarum BFL is not recommended as a viability-enhancing strategy in the Salamines Criollos studied in this work.

The aim of the present work was to characterize Lactiplantibacillus sp. LP5 strain, isolated from pork production, and identify bacteriocin-like inhibitory substances produced by this strain. In this study, LP5 was identified by specie-specific PCR and 16S rDNA sequencing. Additionally, bacterial growth kinetics, antimicrobial activity, detection of the genes related to plantaricins production and genetic expression of plantaricins, were determined. Lactiplantibacillus sp. LP5 was identified as Lactiplantibacillus plantarum. The well-diffusion test using cell-free supernatants (CFS), neutralized CFS, CFS treated with catalase and CFS treated with proteinase K showed that inhibitory effects on a Shiga toxin-producing E. coli (STEC) strain were produced by bacteriocins. The PCR technique allowed the detection of genes encoding E/F plantaricins, as well as J/K and whole genome sequencing and bacteriocin mining analysis allowed us to confirm the presence of these plantaricins. We can conclude that the inhibitory effect of L. plantarum LP5 isolated from pigs against STEC EDL933 strain could be associated with the bacteriocins production and represents a potential use as a probiotic strain.

La Organización Mundial de la Salud (OMS) define salmonelosis como una de las enfermedades transmitida por alimentos (ETA) de mayor casuística, ampliamente extendida en todo el mundo. La enfermedad es producida por Salmonella spp. y causa una de las zoonosis más frecuentes y de mayor impacto económico. El hombre adquiere la infección después de la ingestión de alimentos contaminados, aunque también puede transmitirse de persona a persona o por vía fecal-oral. Actualmente, las técnicas microbiológicas de aislamiento convencional para detección de Salmonella spp. son establecidas por el Código Alimentario Argentino para verificar la aptitud de un producto para consumo, pero éstas requieren de 4 a 5 días para la obtención de un resultado, tiempo que juega en contra para el productor y la conservación de dichos alimentos. Por este motivo en este trabajo se analizan los métodos de diagnóstico tradicional según Normas ISO 6579:2002 con algunas modificaciones, los métodos de inmunoensayo comerciales y la Reacción en Cadena de la Polimerasa técnica (PCR) de detección del gen invA implicado en el proceso de invasión de cepas patógenas. Se analizaron 60 muestras procedentes de canales porcinas destinadas a comercialización. Se detectó un 10% de Salmonella spp. Se pudo determinar que el diagnóstico molecular por PCR posee alta sensibilidad, pero no es alentador el resultado que reflejan los test comerciales inmunocromatográficos ya que queda en evidencia la necesidad de alta carga microbiana para un diagnóstico certero.

The objective of this work was to molecularly and genotypically characterize and test the inhibitory activity of six colicinogenic Escherichia coli strains (ColEc) and their partially purified colicins against STEC O157:H7 isolated from clinical human cases. Inhibition tests demonstrated the activity of these strains and their colicins against STEC O157:H7. By PCR it was possible to detect colicins Ia, E7, and B and microcins M, H47, C7, and J25. By genome sequencing of two selected ColEc strains, it was possible to identify additional colicins such as E1 and Ib. No genes coding for stx1 and stx2 were detected after analyzing the genome sequence. The inhibitory activity of ColEc against STEC O157:H7 used as an indicator showed that colicins are potent growth inhibitors of E. coli O157:H7, being a potential alternative to reduce the presence of pathogens of public health relevance.