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Dairy products have been implicated in foodborne infections caused by different bacterial pathogens. Among them, Listeria monocytogenes is of particular concern due to its ubiquity, resistance to sanitation processes and high mortality rates resulting from infection. These issues make the development of novel methods for the rapid detection of this bacterium of high interest. The evaluation of a novel multiplex real-time Recombinase Polymerase Amplification method including an internal amplification control is reported in the present work. The method performance was compared to that of the European reference method (ISO 11290-1) for the detection of the species in samples from 40 commercial products, including 14 UHT milk samples, 16 hard cheese samples, 6 infant dairy preparation samples and 4 fresh cheese samples. A limit of detection below 10 cfu/25 g or mL sample was achieved, and values higher than 90% were obtained for relative sensitivity, specificity, accuracy, positive and negative predictive values and the index (kappa) of concordance. Analysis was achieved within one working day, compared to the six days required using the ISO method. Moreover, slight modification of the ISO 11290-1 method to include secondary enrichment in half Fraser broth resulted in the confirmation of all positive samples.This study investigated the antimicrobial activities of organic acid vapors against a phytopathogen (Acidovorax citrulli) and foodborne pathogens (Salmonella enterica, Escherichia coli O157H7, and Listeria monocytogenes) on the surface of Cucurbitaceae seeds. Germination percentages of cucumber, honeydew melon and watermelon seeds treated with acetic and propionic acid vapors (100 mg/L) at 50 °C and 43% or 85% relative humidity (RH) for up to 2 h did not significantly (P > 0.05) decrease. Treatment with formic acid significantly (P ≤ 0.05) decreased the germination percentage. The antimicrobial activities of acetic and propionic acid vapors (100 mg/L; 50 °C; 43% or 85% RH) were determined. A. citrulli was inactivated within 1 h on cucumber and watermelon seeds, regardless of type of organic acid or RH. The phytopathogen was reduced to levels below the detection limit (-0.5 log CFU/g) for enrichment on honeydew melon seeds treated with acetic acid vapor. S. enterica and L. monocytogenes were inactivated within 2 h at 85% RH on honeydew melon and watermelon seeds treated with acetic acid and propionic acid vapors. E. coli O157 H7 was inactivated by treatment with acetic acid vapor at 85% RH. This study provides useful information for developing a method to decontaminate Curcurbitaceae seeds using organic acid vapors as lethal agents.Symphony orchestra of multi-microorganisms characterizes the solid-state acetic acid fermentation process of Chinese cereal vinegars. Lactate is the predominant non-volatile acid and plays indispensable roles in flavor formation. This study investigated the microbial consortia driving the metabolism of D-/l-lactate during fermentation. Sequencing analysis based on D-/l-lactate dehydrogenase genes demonstrated that Lactobacillus (relative abundance > 95%) dominated the production of both d-lactate and l-lactate, showing species-specific features between the two types. Lactobacillus helveticus (>65%) and L. reuteri (~80%) respectively dominated l- and d-lactate-producing communities. D-/l-lactate production and utilization capabilities of eight predominant Lactobacillus strains were determined by culture-dependent approach. Subsequently, D-/l-lactate producer L. https://www.selleckchem.com/products/hs-10296.html plantarum M10-1 (dl ≈ 11), l-lactate producer L. casei 21M3-1 (DL ≈ 0.29.8) and D-/l-lactate utilizer Acetobacter pasteurianus G3-2 were selected to modulate the metabolic flux of D-/l-lactate of microbial consortia. The production ratio of D-/l-lactate was correspondingly shifted coupling with microbial consortia changes. Bioaugmentation with L.casei 21M3-1 merely enhanced l-lactate production, displaying ~4-fold elevation at the end of fermentation. Addition of L.plantarum M10-1 twice increased both D- and l-lactate production, while A. pasteurianus G3-2 decreased the content of D-/l-isomer. Our results provided an alternative strategy to specifically manipulate the metabolic flux within microbial consortia of certain ecological niches.Brown rot caused by Monilinia fructicola has led to considerable preharvest and postharvest losses in all major nectarine fruit-growing areas. In our previous study, we successfully identified a biocontrol strain of bacteria, Bacillus licheniformis W10, that can be used to control brown rot. However, the possible mechanism of the control of brown rot by B. licheniformis W10 is still unclear. Therefore, the objectives of this study were to determine whether B. licheniformis W10 induces resistance by activating defense-related enzymes including antioxidant enzymes in nectarine. Treatment of nectarine fruit with B. licheniformis W10 reduced both M. fructicola-induced oxidative damage and reactive oxygen species (ROS) production. Furthermore, application of B. licheniformis to nectarine fruit resulted in a significant increase in the activity of antioxidant and defense-related enzymes and increase in the expression of the corresponding genes. Overall, our results verified the proposed mechanism of B. licheniformis W10 in controlling M. fructicola via regulation of ROS levels and activation of antioxidant and defense-related enzymes.This study aimed to evaluate the effect of Lactobacillus rhamnosus GG on growth of Staphylococcus aureus and Listeria monocytogenes, inoculated alone or in combination on surface of Minas Frescal cheeses, during storage for 21 days at 7 °C. Survival percentages of each individual bacterial species after exposure to in vitro simulated gastrointestinal conditions (SGC) were also determined. The addition of L. rhamnosus did not affect (P > 0.05) pH, moisture, fat, protein and texture profile of Minas Frescal cheeses. L. rhamnosus was able to survive in suitable counts (>6 Log CFU/g) in cheeses from the 7th day of storage, with high survival (>74.6-86.4%) after SGC. An inhibitory effect of L. rhamnosus on L. monocytogenes was observed in cheeses (decrease of 1.1-1.6 Log CFU/g) and after SGC (20% reduction in the survival). No inhibitory effect of L. rhamnosus was observed on S. aureus counts (P > 0.05), and this microorganism did not survive the exposure to SGC. In conclusion, the addition of L. rhamnosus in Minas Frescal cheese has a potential for L.
Here's my website: https://www.selleckchem.com/products/hs-10296.html
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