Search

Aims: The aim of this study was to evaluate the protective capacity of the exopolysaccharide-producing Lactobacillus rhamnosus V5 against invasion in vitro and in vivo with S. typhimurium. Methodology: We tested the antimicrobial activity of the compound extracted from the lactobacilli against S. typhimurium directly, also we tested the interference of this compound in S. typhimurium adherence and invasion of HeLa and HEp-2 cells (in vitro testings). For in vivo experiments, we used 16 BALB/c female mice. Through gavage method we introduced L. rhamnosus as probiotic and then infected mice with S. enterica serovar typhimurium. After euthanasia, spleen, liver and Peyer's patches removed for microbiological and histopathological analysis. Results: The results showed that lactobacilli were able to produce antimicrobial compounds against S. typhimurium. These lactobacilli inhibited the adhesion and invasion of S. typhimurium in HeLa and HEp-2 cells, respectively. The challenge assay in the murine model demonstrated a decrease in pathogen translocation in the spleen and liver from mice treated with probiotic as well as protection of ileal tissue in lactobacilli-treated mice. The histopathological analysis demonstrated the presence of prominent lymphoid nodules in the ileum from the non-treated lactobacilli mice. Conclusion: Our results suggest that L. rhamnosus improved the effectiveness of the intestinal barrier and, thus, could be a potential probiotic to control salmonellosis.

Actualmente, existe una amplia gama de productos farmacéuticos que ofrecen grandes benefi cios para el tratamiento de diversas enfermedades orales. La mayoría de estos productos son de origen sintético con propiedades antibacterianas, pero existen numerosos efectos secundarios asociados con su uso. Una alternativa es el uso de productos naturales de plantas e insectos en la reducción de la carga bacteriana de la cavidad oral como la manzanilla (Chamaemelum nobile (L.) All.), el cacao (Th eobroma cacao L.), el aloe (Aloe vera L.), la moringa (Moringa oleífera Lam.), el orégano (Origanum vulgare L.), coco (Cocos nucifera L.), ajo (Allium sativum L.), clavo (Syzgium aromaticum L.), cardamomo (Elettaria cardamomum L.), stevia (Stevia rebaudiana Bertoni), miel de abeja y propóleos, abordados en esta revisión de la literatura. Esta revisión intenta abordar el uso de diferentes compuestos naturales para reducir la carga bacteriana de la cavidad oral. Se puede concluir que existen varios estudios sobre los efectos de los productos naturales por parte del hombre en la medicina, donde hay una gran cantidad de trabajos y publicaciones relacionadas con sustancias naturales con ingredientes activos para reducir la carga bacteriana de la cavidad oral.

Candida tropicalis is a human pathogen associated with high mortality rates. We have reported a switching system in C. tropicalis consisting of five morphotypes – the parental, switch variant (crepe and rough), and revertant (crepe and rough) strains, which exhibited altered virulence in a Galleria mellonella model. Here, we evaluate whether switching events may alter host-pathogen interactions by comparing the attributes of the innate responses to the various states. All switched strains induced higher melanization in G. mellonella larvae than that induced by the parental strain. The galiomicin expression was higher in the larvae infected with the crepe and rough morphotypes than that in the larvae infected with the parental strain. Hemocytes preferentially phagocytosed crepe variant cells over parental cells in vitro. In contrast, the rough variant cells were less phagocytosed than the parental strain. The hemocyte density was decreased in the larvae infected with the crepe variant compared to that in the larvae infected with the parental strain. Interestingly, larvae infected with the revertant of crepe restored the hemocyte density levels that to those observed for larvae infected with the parental strain. Most of the switched strains were more resistant to hemocyte candidacidal activity than the parental strain. These results indicate that the switch states exhibit similarities as well as important differences during infection in a G. mellonella model.

Com o surgimento das “superbactérias” e a descrição de mecanismos de resistência bacteriana contra diversos medicamentos disponíveis no mercado, se faz necessária a busca por novos bioativos antimicrobianos. Bactérias ambientais têm se mostrado valiosas ferramentas nessa busca, uma vez que têm capacidade de produzir compostos bioativos como produtos de seu metabolismo secundário. Diante deste cenário o presente estudo teve por objetivo a prospecção de bactérias produtoras de antibióticos, bem como estudar alguns parâmetros de produção e estabilidade. Inicialmente, foi feita a caracterização fenotípica de 33 isolados em solo de um fragmento de floresta secundária semidecídua em Londrina-PR, Brasil (23 ° 19'37,8 "S 51 ° 12'22,4" O). Dentre os isolados prospectados, 100% eram Gram positivas, 67% apresentavam a capacidade de produzir endósporos e 94% apresentavam-se na forma de bacilos. Deu-se prosseguimento, então aos testes de atividade antagônica por cultura dupla contra os patógenos Acinetobacter baumannii (oxa23-positivo), Staphylococcus aureus ATCC 29213 e Escherichia coli ATCC 8739 apenas com os isolados que apresentavam morfologia de bacilos e capacidade de produzir endósporos. Dentre os 22 isolados submetidos ao teste de cultura-dupla, LABIM 17 o único isolado capaz de inibir todos os três marcadores, mostrando assim uma atividade de amplo espectro. A identificação molecular por rDNA 16S classificou LABIM17 como Brevibacillus sp. LABIM 17. Por fermentação liquida submersa foi avaliado a produção de metabolitos extracelulares antibacterianos por LABIM 17. Os resultados obtidos demostraram a produção de metabólitos extracelulares antibacterianos em meio MAK a partir de 72 h. Afim de avaliar a estabilidade dos metabólitos, sobrenadante livre de células foram submetidos a diferentes temperaturas e comprimentos de onda de luz visível e UV. Os resultados demostraram que os metabólitos foram estáveis a temperaturas abaixo de 70°C e sob todos os comprimentos de onda testados. Em antecipação a futuras análises genômicas em profundidade e suas aplicações potenciais, realizamos o sequenciamento completo do genoma da LABIM 17 e foi identificada como Brevibacillus brevis. Em análises preliminares de agrupamentos gênicos envolvidos na biossíntese de metabólitos secundários antibacterianos foram identificados agrupamentos para produção de Petrobactina, Octapeptina, Tirocidina, Gramicidina, Zwittermicin e Aurantinina. Todos estes resultados sugerem que B. brevis LABIM 17 tem um bom potencial para uso como agente produtor de antibacterianos, porém mais estudos são necessários para purificação, caracterização e aumento de produção dos compostos antibacterianos. The raise of “superbacteria” and discovery of bacterial antibiotic resistance mechanisms against several clinical available drugs created the need to seek new antibacterial drugs. Environment microorganisms are interesting sources for this purpose, considering they harbor the ability to produce antibacterial molecules as products of their secondary metabolism. Hence, this study aimed to prospect bacteria from the environment which produces active molecules against other bacteria and describe these molecules in terms of stability and means of producing them. Initially, we characterized the phenotypes of 33 strains from a soil sample collected in secondary semi-deciduous forest in Londrina-PR, Brazil (23 ° 19'37,8 "S 51 ° 12'22,4" O). Among those, 100% were Gram positive, 67% were endospore-forming and 94% had bacilli morphology. Using only the bacilli observed to be endospore-forming, antagonist activity tests were performed in double culture against the pathological bacteria Acinetobacter baumannii (oxa23-positivo), Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 8739. From these tests, we selected LABIM17 as the only strain capable of inhibit growing in all three markers, indicating ample spectrum of antibacterial activity. Molecular identification using rDNA 16S allowed us to classify LABIM17 as Brevibacillus sp. Submerged liquid fermentation was done to assess the extracellular antibacterial metabolites production by LABIM17. Results showed the production of such metabolites happen in MAK medium after 72h of incubation. Supernatant free of cells were exposed to different temperatures and light wavelengths ranging from UV to visible light in order to evaluate molecular stability. Results from this test indicated the metabolites were stable at temperatures below 70°C and at all light wavelengths tested. To further identify LABIM17 we follow-up our analysis with genome sequencing, allowing future deep genomic analysis in our lab and identifying LABIM17 as Brevibacillus brevis. Preliminary analysis of genic groups involved in the biosynthesis of molecules from secondary metabolism with antibacterial activity, we identified groups associated with production of Petrobactin, Octapeptin, Tirocidine, Gramicidin, Zwittermicin and Aurantinine. Taken together, our results suggests that B. brevis (LABIM17) is a potential candidate to source for antibacterial molecules, nevertheless more studies are needed to purify and characterize such molecules, as well as optimize its production using LABIM17 cultures.