Interaction between the probiotic Bacillus subtilis and Salmonella Typhimurium in Caco-2 cell culture.

BACKGROUND AND OBJECTIVES: Bacillus probiotics have been recently considered in biotechnological researches, and food additives. The present study was aimed to investigate the effects of Bacillus subtilis probiotics (PY79 and ATCC 6633) and their metabolites on Salmonella Typhimurium in Caco-2 cells. MATERIALS AND METHODS: Cytotoxicity of B. subtilis ATCC 6633 crude supernatant (CS) was evaluated by 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. S. Typhimurium invasion assay was performed in the presence of the probiotics. Cell viability, apoptosis, and necrosis were evaluated in presence of S. Typhimurium, B. subtilis strains, and CS (4%, 8%) using flow cytometry. RESULTS: Results showed a significant reduction in the invasive ability of S. Typhimurium to Caco-2 cells by employing B. subtilis probiotics, and CS (p < 0.05). The less invasion was indicated in B. subtilis PY79 and Salmonella co-cultural group. Furthermore, the cell survival rates, and apoptosis/necrosis were respectively increased and decreased in co-culture groups (p < 0.05). CONCLUSION: Hence, it seems that B. subtilis strains could be suggested as beneficial candidates to overcome the invasion and cytotoxicity of Salmonella on the intestinal cells. However, additional in vivo models are suggested to validate our results.

Cytotoxicity, apoptosis, and IL-8 gene expression induced by some foodborne pathogens in presence of Bacillus coagulans in HT-29 cells.

Food poisoning caused by bacteria is one of the most important concerns in food hygiene. The use of probiotics in prevention, control, and treatment of these infections has been considerably increased in recent years. This study evaluated the effect of B. coagulans cell free supernatant (CFS) on growth of Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, non-pathogenic Escherichia coli, and Escherichia coli 0157:H7 by the broth dilution method. The cytotoxicity, and apoptosis induced by pathogens alone and in co-culture with B. coagulans or its CFS were measured by trypan blue, and fluorescence staining methods. The expression level of interleukin-8 (IL-8) cytokine-encoding genes was also investigated by a qRT-PCR assay in all pathogens and co-cultured groups in HT-29 cells. Our results showed that 4% B. coagulans CFS reduced pathogen growth. The highest rate of growth inhibition was observed in L. monocytogenes. We also found that B. coagulans, and its 4% CFS reduced the cytotoxic effects of pathogens, with the exception of S. aureus. Non-pathogenic E. coli also had no significant cytotoxic effect on the cells. Examination of the treated cells with acridine orange/ethidium bromide staining showed reductions in the rate of cell damage (including early apoptosis, late apoptosis, and necrosis) in pathogen-probiotic co-cultures. Furthermore, we showed that co-culture of pathogens with B. coagulans significantly down-regulated IL-8 gene expression (P < 0.05). The greatest down-regulation compared with pathogen alone was observed in S. aureus. Hence, B. coagulans can be considered as an appropriate probiotic to diminish cytotoxicity, and inflammatory response of enteropathogenic bacteria.

Prevalence of Brucella species in unpasteurized dairy products consumed in Shiraz province using PCR assay.

The consumption of milk and unpasteurized dairy products contaminated with Brucella bacteria is one of the most important ways of brucellosis transmission to humans. The principal goal of this study was to determine the prevalence of Brucella abortus (B. abortus) and Brucella melitens (B. melitens) in unpasteurized dairy products consumed in Shiraz province. In this study conducted in 2016, 238 unpasteurized dairy products including 48 raw milk, 48 yogurt, 46 cheeses, 48 dough and 48 ice cream samples, were purchased from the retail market in Shiraz province and were examined by a specific PCR assay. This study showed positive 5/04% out of 238 unpasteurized dairy products including 9 out of 48 (18/75%) raw milk samples and 3 out of 48 (6.25%) yogurt samples). Contamination was not detected in samples of dough, cheese and traditional ice cream. The results also showed that among 12 positive samples, 6 samples were contaminated with B. abortus (including 4 milk samples and 2 yogurt samples), 2 samples were contaminated with B. melitensis (including 2 Milk samples) and 4 samples were contaminated simultaneously with B. abortus and B. melitensis (including 3 milk samples and 1 yogurt sample). The present study suggests the unpasteurized dairy products as the major sources of brucellosis in Shiraz province, South of Iran; thus, to prevent brucellosis in human, the consumption of pasteurized milk and dairy products is highly recommended.

Green synthesis of gold nanoparticles by using Ferula persica Willd. gum essential oil: production, characterization and in vitro anti-cancer effects.

OBJECTIVES: Synthesizing and characterization of gold nanoparticles (Au NPs) by Ferula persica gum essential oil and investigating in vitro anti-cancer effects. METHODS: Characterization of NPs was performed. Cytotoxicity and apoptosis were determined on cancerous CT26 and non-cancerous Vero cells using MTT assay and acridine orange/ethidium bromide (AO/EB) staining, respectively. Clonogenic assay was also performed. KEY FINDINGS: The absorption peak in UV-visible spectroscopy was at 530 nm. In TEM image, Au NPs were spherical in shape with average size of 37.05 nm (78.6 nm in DLS analysis). Comparison of the FTIR spectrum of the Au NPs with the essential oil revealed the presence of compounds responsible for reducing and capping the gold ions. XRD pattern showed metal crystal structure. Au NPs exerted dose-dependent cytotoxicity with IC50 values of 0.0024 and 0.0307 mg/ml against CT26 and Vero cell lines, respectively. Au NPs induced apoptosis on both cell lines with statistically more intense effect on CT26 cells (P < 0.0001). Colony formation of CT26 and Vero cells was also inhibited in comparison to untreated cells (P < 0.05). CONCLUSIONS: Ferula persica gum can be successfully used for green production of Au NPs. Au NPs show in vitro anti-cancer activity including cytotoxic, apoptotic and antiproliferative effects.

The effects of probiotic Bacillus coagulans on the cytotoxicity and expression of alpha toxin gene of Clostridium perfringens type A.

Around the world, Clostridium perfringens type A is known to be a common foodborne pathogen. Therefore, the control and treatment of food poisoning caused by this pathogen are important. This study investigated, in vitro, the effects of Bacillus coagulans and its culture extracts on alpha toxin gene expression, growth inhibition, cytotoxicity, and apoptosis induced by C. perfringens spore, germinated spore and its enterotoxin. Flow cytometry was used to evaluate the apoptosis rate, and MTT test was used to evaluate cytotoxicity. Minimum inhibitory concentration was also used to measure the percentage of inhibition in the broth medium. Finally, RT-qPCR was used to evaluate alpha toxin gene expression. The results showed that the B. coagulans culture extract was able to inhibit the growth of the germinated spore of C. perfringens. Moreover, treating the extract with pepsin can reduce growth in the broth medium. MTT and flow cytometry showed that both B. coagulans and its extract can significantly reduce the cytotoxicity and apoptosis rate induced by C. perfringens type A. In addition, it was shown that the co-culture of B. coagulans and C. perfringens decreases alpha toxin gene expression. The findings of this study indicate that B. coagulans, with growth inhibition and reduced expression of alpha toxin in C. perfringens, can reduce the cytotoxicity and apoptosis rate induced on HT-29 cells.