BackgroundBiofilm production represents an important virulence and pathogenesis factor for Staphylococcus aureus. The formation of biofilms on medical devices is a major concern in hospital environments, as they can become a constant source of infection. Probiotic bacteria, such as Lactobacillus fermentum and L. plantarum, have been found to inhibit biofilm formation; however little is known about the underlying mechanism. In this study, we tested the activity of supernatants produced by L. fermentum TCUESC01 and L. plantarum TCUESC02, isolated during the fermentation of fine cocoa, against S. aureus CCMB262 biofilm production. We measured inhibition of biofilm formation in vitro and analyzed biofilm structure by confocal and electronic microscopy. Additionally, we quantified the expression of S. aureus genes icaA and icaR involved in the synthesis of the biofilm matrix by real-time PCR.ResultsBoth Lactobacillus supernatants inhibited S. aureus growth. However, only L. fermentum TCUESC01 significantly reduced the thickness of the biofilm, from 14 μm to 2.83 μm (at 18 mg∙mL−1, 90 % of the minimum inhibitory concentration, MIC), 3.12 μm (at 14 mg∙mL−1, 70 % of the MIC), and 5.21 μm (at 10 mg∙mL−1, 50 % of the MIC). Additionally, L. fermentum TCUESC01 supernatant modulated the expression of icaA and icaR.Conclusions L. fermentum TCUESC01 reduces the formation of S. aureus biofilm under subinhibitory conditions. Inhibition of biofilm production probably depends on modulation of the ica operon.

Probiotic lactic acid bacteria are known for their ability to modulate the immune system. They have been shown to inhibit inflammation in experiments with animal models, cell culture, and clinical trials. The objective of this study was to elucidate the anti-inflammatory potential of Lactobacillus plantarum Lp62, isolated from cocoa fermentation, in a cell culture model. Lp62 inhibited IL-8 production by Salmonella Typhi-stimulated HT-29 cells and prevented the adhesion of pathogens to these epithelial cells. The probiotic strain was able to modulate TNF-α, IL1-β, and IL-17 secretion by J774 macrophages. J774 activation was reduced by coincubation with Lp62. PBMC culture showed significantly higher levels of CD4+CD25+ T lymphocytes following treatment with Lp62. Probiotics also induced increased IL-10 secretion by mononuclear cells. L. plantarum Lp62 was able to inhibit inflammatory stimulation in epithelial cells and macrophages and activated a tolerogenic profile in mononuclear cells of healthy donors. These results indicate this strain for a possible application in the treatment or prevention of inflammatory diseases.

The use of intestinal probiotic bacteria is very common in the food industry and has been the focus of the majority of research in this field. Yet in recent years, research on extraintestinal microorganisms has greatly increased due to their well-known potential as probiotics. Thus, we studied a strain of Lactobacillus fermentum (TCUESC01) extracted from fermenting cocoa. First, we examined the impact of pH on the growth of this strain and studied its survival under conditions similar to those of the human gastrointestinal tract. L. fermentum TCUESC01 demonstrated resistance to conditions mimicking the human stomach and intestines and grew well between pH 5 and pH 7. Next, we subjected L. fermentum TCUESC01 to storage at 4°C in a milk solution and found that it survived well for 28 days. Lastly, we measured the susceptibility of this strain to numerous antibiotics and its tendency to autoaggregate. L. fermentum TCUESC01 showed significant autoaggregation, as well as susceptibility to the majority of antibiotics tested. Overall, our findings support the potential use of this extraintestinal bacterium as a dietary probiotic.

Um levantamento sobre o nível de poluição dos Rios Cachoeira e Santana (Ilhéus, Bahia, Brasil) foi realizado durante um trimestre, por meio da avaliação da qualidade microbiológica da água e de frutos do mar (Crassostrea rhizophorae - ostra-do-mangue e Tagelus plebeius - moapem) extraídos desses rios. Tradicionais indicadores de poluição como coliformes totais (Ct) e coliformes termotolerantes (CT), além de contagem padrão de microrganismos, com isolamento e identificação das enterobactérias, foram determinados nas amostras dos rios, os quais exibiram diferentes níveis de poluição fecal. Foram isolados 68 microrganismos, distribuídos em dez espécies, dentre elas, Salmonella typhi, Escherichia coli e Shigella sp., alertando para o risco do consumo in natura desses moluscos, mesmo quando em conformidade com a legislação estabelecida para CT. A prospecção de moluscos para o acompanhamento dos índices de poluição não se mostrou efetiva considerando a pesquisa de CT em ostras e moapens. Verificou-se também o maior grau de contaminação no Rio Cachoeira, o qual serve de base para distribuição de água na região e como fonte de subsistência, por meio da atividade extrativista, para a população ribeirinha.

ABSTRACT. We investigated the probiotic potential of lactic acid bacteria (LAB) obtained from cocoa fermentation using an experimental rat model of colitis. Cocoa beans were collected from fermentation boxes every 12 h for 5 days to isolate the microorganisms. Strains were isolated by serial dilution and plating on MRS agar. Gram-positive and catalase-negative rods were subjected to DNA extraction, polymerase chain reaction, and sequencing. Ten strains were randomly pooled and used to prepare a fermented milk drink that was used to treat the experimental colitis. A parallel group was treated with a single strain drink. Serum concentrations of cytokines and IgA, total and differential counts of blood leukocytes, and histological appearance were compared with the untreated control colitis group. Eighty strains of LAB were identified as Lactobacillus fermentum (68) and Lactobacillus plantarum (12). The multi-strain LAB pool significantly reduced the total number of leukocytes. There was a significant reduction in the percentage of neutrophils and monocytes compared with the control colitis group. IFN-γ concentration was downregulated in animals treated with the LAB pool. IL-10 and IgA increased significantly in the group treated with the strains. Histological analysis showed that the LAB pool reduced the inflammatory infiltrate and restored tissue architecture. The group treated with the single strain LAB drink (L. fermentum) showed no signs of inflammation remission. The results confirm the probiotic action of cocoa-derived LAB in the treatment of experimental colitis. Studies using isogenic models and humans will clarify the mechanisms of immune response modulation in inflammatory bowel disease.