Antibacterial and Antioxidant Properties of Extracts of Yucca Baccata, a Plant of Northwestern Mexico, against Pathogenic Bacteria.

Introduction: Bacterial agents and oxidative reactions are involved in health and food preservation issues, and Yucca baccata (Y. baccata) can be a source of compounds with practical applications in both areas, but its investigation remains limited. Materials and Methods: Butanolic (YBE) and aqueous (YAE) extracts were obtained from the stem of Y. baccata. The total saponin, phenolic, and flavonoid contents were analyzed in the YBE and YAE. The antioxidant capacity of the extracts was determined by the DPPH, TEAC, FRAP, and ORAC assays. Seven Gram-positive and five Gram-negative pathogenic bacteria strains were used to determine the MIC and MBC. Results: Saponin contents were 30% and 1.81% (w/w) in the YBE and YAE, respectively. The total phenolic and flavonoid contents in the extracts were 29.5 µg GAEmg-1 (2.95%) and 5.58 µg GAEmg-1 (0.56%) in the YBE and 69.92 µg QEmg-1 (7.0%) and 1.65 µg QEmg-1 (0.165%) in the YAE. The antioxidant capacity values of YBE were 29.18 µg TEmg-1, 121.8 µg TEmg-1, 33.41 µg TEmg-1, and 156.84 µg TEmg-1 by the DPPH, TEAC, FRAP, and ORAC assays, respectively. YAE had lower antioxidant values than YBE (P < 0.05). Values of 80 mgmL-1 and 100 mgmL-1 were estimated for MIC and MBC of YBE against the Gram-positive bacteria. Values of 100 mgmL-1 and 120 mgmL-1 for MIC and MBC of YBE were estimated against the Gram-negative bacteria. No MIC and MBC were obtained for YAE. Conclusion: YBE exhibited higher antioxidant activity than YAE. Apparently, antibacterial properties of the YBE tended to be higher than those of the YAE.

Caracterización polifásica de salmonella spp: Aislada de campos agrícolas de melón (cucumis melo) y cilantro (coriandrum sativum) / Polyphasic typing of salmonella spp: Isolated from cantaloupe melon (cucumis melo) and coriander (coriandrum sativum) fields / Caracterização polifásica de salmonella spp: Isolada de campos agrícolas de melão (cucumis melo) e coentro (coriandrum sativum)

Se evaluó la diversidad serológica y genética de cepas de Salmonella spp. aislada de campos de cultivo de melón Cantaloupe (Cucumis melo) y cilantro (Coriandrum sativum). Para identificar al patógeno se realizaron pruebas bioquímicas, serología, susceptibilidad a antibióticos y caracterización por PFGE. Se encontraron 11 muestras contaminadas de los campos de cilantro y 7 de los de melón. Se aisló Salmonella anatum y S. give, principalmente. Solo una de las cepas presentó resistencia a tobramicina. El PFGE mostró que cepas del mismo serogrupo, produjeron patrones electroforéticos similares y el análisis polifásico desplegó cinco grupos distintos con similitud menor al 35%. Es necesario intensificar las buenas prácticas agrícolas y de producción, ya que los serogrupos identificados han sido involucrados en brotes epidémicos. Por otro lado, el análisis polifásico mostró variabilidad genómica y además permite suponer que las cepas de S. give son clonales, no así para S. anatum, que estuvo presente en diferentes muestras.

The serological and genetic diversity of Salmonella spp. strains isolated from Cantaloupe melon (Cucumis melo) and coriander (Coriandrum sativum) fields were evaluated. Biochemical test, serology, antibiotic resistance and PFGE were performed to identify isolated strains. Eleven contaminated samples from coriander fields were found, and seven from melon fields. The serogroups identified were mainly Salmonella anatum and S. give. Only one strain was resistant to tobramicyn. PFGE showed five electrophoretic profiles, in agreement with the identified serotypes and in the polyphasic analysis five clusters were observed (<35% similarity). It is necessary to implement good agricultural and production practices, since identified serogroups have been involved in epidemic outbreaks. Moreover, the polyphasic analysis showed genomic variability and also suggests that strains of S. give are clonal. It is not the same for S. anatum strains, which were isolated from different samples.

Avaliou-se a diversidade sorológica e genética de cepas de Salmonella spp. isolada de campos de cultivo de melão Cantalupo (Cucumis melo) e coentro (Coriandrum sativum). Para identificar ao patógeno foram realizadas provas bioquímicas, sorologia, suscetibilidade a antibióticos e caracterização por PFGE. Encontraram-se 11 amostras contaminadas dos campos de coentro e 7 dos de melão. Isolou-se Salmonella anatum e S. give, principalmente. Somente uma das cepas apresentou resistência à tobramicina. O PFGE mostrou que cepas do mesmo sorogrupo, produziram padrões eletroforéticos similares e a análise polifásica desprendeu cinco grupos distintos com similitude menor a 35%. É necessário intensificar as boas práticas agrícolas e de produção, já que os sorogrupos identificados têm sido envolvidos em surtos epidêmicos. Por outro lado, a análise polifásica mostrou variabilidade genômica e além disso permite supor que as cepas de S. give são clonais, não sendo assim para S. anatum, que esteve presente em diferentes amostras.

An alternative method for evaluation of resistance to low pH and bile salts in probiotic characterization of Lactobacillus reuteri strains: a technical note

A considerable amount of attention has been focused on the use of lactobacilli as probiotics. The use of microorganisms as probiotics must meet certain criteria, among these; the resistance to low pH and bile salts is of great importance. Different procedures have been designed to evaluate tolerance to gastrointestinal transit. Since resistance to low pH and bile salts is critical in the evaluation of probiotic strains, the aim of this study was to compare resistance to bile salts for 20 strains of porcine Lactobacillus reuteri that had been isolated from healthy pigs, using two different procedures based on exposure to low pH. Statistical analysis revealed no difference in resistance of the strains to bile salts whether pH was low or not. The use of low pH prior to exposure to bile salts therefore more closely represents physiological conditions that should be used for the evaluation of potential porcine probiotic lactobacilli. Further studies using digestive enzymes are required to evaluate resistance to gastrointestinal transit, since it is an important factor in the evaluation of strains with potential probiotic activity.

Existe un interés creciente en el uso de lactobacilos como probióticos. El uso de microorganismos como probióticos, requiere que éstos cubran ciertos requisitos, dentro de los cuales la resistencia a pH ácido y a sales biliares, se consideran de suma importancia. Actualmente existen distintos procedimientos que permiten evaluar la tolerancia al tránsito gastrointestinal. Debido a que la resistencia a pH ácido y a sales biliares es una condición crítica dentro de la evaluación de cepas probióticas, la finalidad del presente trabajo consistió en comparar la resistencia a sales biliares de 20 cepas de Lactobacillus reuteri aisladas de cerdos sanos, mediante dos procedimientos diferentes basados en la exposición a pH ácido. El análisis estadístico no mostró diferencias en la resistencia de las cepas a sales biliares cuando se realizó una exposición previa a pH ácido. Así, la exposición a pH ácido previo a la incubación con sales biliares, asemeja más a las condiciones fisiológicas que el microorganismo encontrará de manera natural y es una buena alternativa en la evaluación probiótica de lactobacilos de origen porcino. Se requieren estudios que incluyan enzimas digestivas, con el fin de evaluar la resistencia al tránsito gastrointestinal, dado que es uno de los factores más importantes en la evaluación de cepas con potencial actividad probiótica.

Resistance of Enterococcus strains isolated from pigs to gastrointestinal tract and antagonistic effect against Escherichia coli K88.

The intestinal flora plays an important role in health and wellbeing of different organisms. Indigenous microflora can be innocuous or pathogenic. Consumption of food supplemented with beneficial microorganisms as probiotics provides a good health state and this can be maintained and recovered. Currently, probiotic strains of Bifidobacterium and Lactobacillus are widely used in humans as well as animals. Swine industry would benefit with the application of probiotics, mainly to overcome diarrheal diseases produced by different causes, as a pathogenic E. coli K88. The aim of this work was to isolate strains of Enterococcus from gastrointestinal tract of pigs to use them as probiotic. Two strains of E. faecalis, 2 of E. mundii and 7 of E. faecium were isolated with characteristics of resistance to acid pH, tolerance to biliary salts and a high antagonistic activity (>80%) against E. coli K88. Based on their characteristics and species affinity, we believe that these strains could be administered to pigs as a probiotic.