Browsing by Subject "plant extracts"
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Item Effect of natural antimicrobials against Salmonella, Escherichia coli o157:h7 and Listeria monocytogenes(2009-05-15) Cuervo Pliego, Mary PiaSalmonella, Escherichia coli O157:H7 and Listeria monocytogenes are pathogens that have caught the attention of federal agencies and researchers due to their great economic impact when illnesses occur. To reduce the presence of these pathogens, different approaches have been used. However, since the global consumer?s demand for natural ingredients is steadily increasing, the investigation of the effectiveness of potential natural antimicrobials is necessary. In this study, the in vitro antimicrobial activity of Hibiscus sabdariffa L extracts against Salmonella, E. coli O157:H7 and L. monocytogenes was investigated. Furthermore, H. sabdariffa L and ?-polylysine were evaluated to reduce populations of Salmonella and E. coli O157:H7 in ground beef. The minimum inhibitory concentration (MIC) of H. sabdariffa L extracts against Salmonella and E. coli O157:H7 was 6,489 ?g/mL and for L. monocytogenes, 5,309 ?g/mL. The minimum bactericidal concentration (MBC) of H. sabdariffa L extracts against Salmonella, E. coli O157:H7 and L. monocytogenes was 19,467, 58,400 and 29,200 ?g/mL, respectively. The exposure to 58,400 ?g/mL of H. sabdariffa extract at 25 oC for 12 h resulted in reductions of more than 6.0 log CFU/mL for any of the 3 pathogens tested. Ground beef inoculated with S. Agona (GFP) and E. coli O157:H7 (RFP) was subjected to 5 decontamination treatments. Three of the treatments were using H. sabdariffa L and the remaining ?-polylysine. S. Agona (GFP) was reduced in 1.1 log cycles using 10% of ground H. sabdariffa L and E. coli O157:H7 (RFP) was reduced 0.9 log cycles using 400 ppm of ?-polylysine. If these natural antimicrobials are combined with current antimicrobial technologies to form a hurdle effect, higher pathogen reductions could be achieved. Reductions in the presence of pathogens in food may lead into reductions in the incidence of foodborne diseases.Item Evaluation of the Antimicrobial Activity from Secondary Metabolites in Different Plant Families (Boraginaceae, Fabaceae, Lamiaceae, and Lauraceae)Compean, Kassandra Lorraine; Ynalvez, Ruby A.For several decades, there has been an increased interest in the antimicrobial activities of different extracts obtained from traditional medicinal plants. There are more than 20,000 species of plants used in traditional medicines. Drugs can be derived from natural products, which are usually secondary metabolites and their derivatives. The increased prevalence of antibiotic-resistant bacteria emerging from the extensive use of antibiotics may render the current antimicrobial agents insufficient to control at least some bacterial infections. Therefore, the search for new antimicrobial agents is an important line of research. The objective of this study was to determine the antimicrobial activities of plant extracts from Sassafras albidum (Nutt.), Ehretia anacua (Terán & Berl.), Melissa officinalis (Linn.), Eysenhardtia texana (Scheele), and Melissa odorata. The ethanol and aqueous extracts were prepared for each of the five plant species and tested against Staphylococcus aureus, Pseudomonas aeruginosa, methicillin-resistant S. aureus, and vancomycin-resistant Enterococci faecium. The ethanol E. anacua extract was found to have a potential for anti-S. aureus activity. E. anacua was also subjected to soxhlet extractions with acetone, diethyl ether, and ethanol. These extracts were tested against S. aureus, P. aeruginosa, Yersinia enterocolitica, Escherichia coli, Serratia marcescens, Candida albicans, Aspergillus niger, and Trichophyton mentagrophytes. The ethanol and diethyl E. anacua extracts were found to have anti-S. aureus activity. HPLC successfully isolated one major phytoconstitutent. Phytochemical analysis showed detectable presence of alkaloids and diterpenes in the ethanol and diethyl E. anacua extracts.