RESUMEN
To date, the selection of candidate strains for probiotic development in production animals has been largely based upon screens for desired phenotypic traits. However, increasing evidence indicates that the use of host-specific strains may be important, because coevolution with the animal host better prepares a bacterial strain to colonize and succeed in its respective host animal species. This concept was applied to Lactobacillus johnsonii in commercial poultry production because of its previous correlation with enhanced bird performance. Using 204 naturally isolated chicken- and turkey-source L. johnsonii, we demonstrate that there is a strong phylogenetic signal for coevolution with the animal host. These isolates differ phenotypically, even within host source, and these differences can be correlated with certain L. johnsonii phylogenetic clades. In commercial turkey poults, turkey-specific strains with strong in vitro phenotypes performed better early in life than strains lacking those phenotypes. A follow-up performance trial in broiler chickens demonstrated that chicken-specific strains result in better overall bird performance than nonchicken-specific strains. Collectively, this work provides evidence for the impact of host adaptation on a probiotic strain's potential. Furthermore, this top-down approach is useful for screening larger numbers of isolates for probiotic candidates.
Asunto(s)
Lactobacillus johnsonii , Probióticos , Animales , Lactobacillus/genética , Aves de Corral , Filogenia , Especificidad del Huésped , Pavos , Pollos/microbiología , Probióticos/farmacologíaRESUMEN
Effects of turkey-derived beneficial bacteria Lactobacillus ingluviei UMNPBX19 and Lactobacillus salivarius UMNPBX2 on Salmonella Heidelberg (SH) in turkey poults was investigated. Using in vitro studies, we determined each strain's resistance to pH 2.5 and 0.3% bile salts and their ß-hemolysis activity. We also tested each strain's adherence to avian epithelial cells and exhibition of antimicrobial activity against major poultry-associated Salmonella. Moreover, using three in vivo experiments, we determined the effect of the strains in combination (LBIS) against SH in turkey poults. The treatment groups were negative control (-SH, -LBIS), SH control (+SH, -LBIS), and LBIS group (+SH, +LBIS). Supplementation of LBIS was done in drinking water throughout the study at a dose of 8 log CFU/gal. On day 7, poults were challenged with a 2011 ground turkey outbreak strain of SH at 5 × 105 CFU/mL, and the surviving pathogens were determined on day 7 postinoculation from the cecum, spleen, and liver. Both Lactobacillus strains exerted resistance to low pH and bile salts ( P < 0.05), showed adhesion to epithelial cells ( P < 0.05), but did not exhibit ß-hemolysis. Cell-free culture supernatants of strains showed antimicrobial activity against Salmonella ( P < 0.05). Results from the in vivo studies revealed that LBIS significantly reduced dissemination of SH to the liver and spleen in all experiments, and colonization in the cecum in two of the three experiments (1.9- and 3.9-log CFU/g reductions), compared with the control. The results indicate that turkey-derived L. ingluviei UMNPBX19 and L. salivarius UMNPBX2 have potential beneficial effects against SH in turkeys. However, more studies to this effect are warranted.
Asunto(s)
Antibiosis , Lactobacillus/fisiología , Ligilactobacillus salivarius/fisiología , Salmonella/crecimiento & desarrollo , Pavos/microbiología , AnimalesRESUMEN
Listeria monocytogenes (LM) is a major foodborne pathogen causing septicemia, meningitis and death in humans. LM infection is preceded by its attachment to and invasion of human intestinal epithelium followed by systemic spread. The major virulence factors in LM include motility, hemolysin and lecithinase production. Reducing LM attachment to and invasion of host tissue and production of virulence factors could potentially control listeriosis in humans. This study investigated the efficacy of sub-inhibitory concentrations (SICs, concentrations not inhibiting bacterial growth) of three, generally regarded as safe (GRAS)-status, plant-derived antimicrobial compounds in reducing LM attachment to and invasion of human colon adenocarcinoma (Caco-2) and human brain microvascular endothelial cells (HBMEC). Additionally, the effect of these compounds on the aforementioned LM virulence factors was studied. The compounds and their respective SICs used relative to their MICs were trans-cinnamaldehyde (TC 0.50mM, 0.75mM with the MIC of 0.90mM), carvacrol (CR 0.50mM, 0.65mM with the MIC of 0.75mM), and thymol (TY 0.33mM, 0.50mM with the MIC of 0.60mM). All three-plant antimicrobials reduced LM adhesion to and invasion of Caco-2 and HBMEC (p<0.05). The compounds also decreased LM motility, hemolysin production and lecithinase activity (p<0.05). Real-time PCR data revealed that TC, CR, and TY down-regulated the expression of LM virulence genes by >3.0 folds compared to controls (p<0.05). Results suggest that TC, CR, and TY could potentially be used to control LM infection; however, in vivo studies are necessary to validate these results.
Asunto(s)
Antiinfecciosos/farmacología , Regulación hacia Abajo , Listeria monocytogenes/patogenicidad , Extractos Vegetales/farmacología , Factores de Virulencia/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/fisiología , Encéfalo/citología , Células CACO-2 , Técnicas de Cultivo de Célula , Células Endoteliales , Enfermedades Transmitidas por los Alimentos/prevención & control , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Humanos , Listeria monocytogenes/genética , Listeria monocytogenes/fisiología , Listeriosis/prevención & control , Fosfolipasas/metabolismo , Virulencia/genética , Factores de Virulencia/genéticaRESUMEN
The efficacy of carvacrol (CAR), trans-cinnamaldehyde (TC), eugenol (EUG) and ß-resorcylic acid (BR) as a wash treatment for reducing Salmonella spp. on tomatoes was investigated. Plum tomatoes inoculated with a six-serotype mixture of Salmonella (108CFU) were subjected to washing in sterile deionized water (control) or deionized water containing chlorine (100 ppm), CAR (0.25 and 0.75%), TC (0.5 and 0.75%), EUG (0.25 and 0.75%), or BR (0.75 and 1.0%) for 15 sec, 1 min, and 3 min. The plant molecules were more effective (P<0.05) in reducing Salmonella on tomatoes compared to washing in water and chlorine. Both concentrations of CAR and TC, and 0.75% EUG decreased Salmonella counts on tomatoes by~6.0 log CFU/ml at 1 min. Both concentrations of BR decreased the pathogen on tomatoes to undetectable levels at 3 min of exposure. Washing of tomatoes in deionized water and chlorine for 3 min reduced Salmonella by ca. 2.0 and 4.0 log CFU/ml, respectively. No Salmonella was detected in the wash water containing the plant molecules or chlorine, whereas a substantial population of the pathogen survived in the control wash water. Moreover, none of the dipping treatments had any effect on the red color of tomatoes (P>0.05). Results indicate that CAR, TC, EUG and BR could effectively be used to kill Salmonella on tomatoes, but additional studies on sensory and quality characteristics of tomatoes treated with plant molecules are warranted.
Asunto(s)
Antiinfecciosos/farmacología , Manipulación de Alimentos/métodos , Microbiología de Alimentos , Viabilidad Microbiana , Extractos Vegetales/farmacología , Salmonella/efectos de los fármacos , Solanum lycopersicum/microbiología , Recuento de Colonia Microbiana , Viabilidad Microbiana/efectos de los fármacos , Salmonella/fisiología , Factores de Tiempo , Agua/químicaRESUMEN
The effect of trans-cinnamaldehyde (TC) on the inactivation of Escherichia coli O157:H7 in undercooked ground beef patties was investigated. A five-strain mixture of E. coli O157:H7 was inoculated into ground beef (7.0log CFU/g), followed by addition of TC (0, 0.15, and 0.3%). The meat was formed into patties and stored at 4 degrees C for 5 days or at -18 degrees C for 7 days. The patties were cooked to an internal temperature of 60 or 65 degrees C, and E. coli O157:H7 was enumerated. The numbers of E. coli O157:H7 did not decline during storage of patties. However, cooking of patties containing TC significantly reduced (P<0.05) E. coli O157:H7 counts, by >5.0log CFU/g, relative to the reduction in controls cooked to the same temperatures. The D-values at 60 and 65 degrees C of E. coli O157:H7 in TC-treated patties (1.85 and 0.08min, respectively) were significantly lower (P<0.05) than the corresponding D-values for the organism in control patties (2.70 and 0.29min, respectively). TC-treated patties were more color stable and showed significantly lower lipid oxidation (P<0.05) than control samples. TC enhanced the heat sensitivity of E. coli O157:H7 and could potentially be used as an antimicrobial for ensuring pathogen inactivation in undercooked patties. However detailed sensory studies will be necessary to determine the acceptability to consumers of TC in ground beef patties.
Asunto(s)
Acroleína/análogos & derivados , Escherichia coli O157/efectos de los fármacos , Conservación de Alimentos/métodos , Productos de la Carne/microbiología , Acroleína/farmacología , Animales , Bovinos , Recuento de Colonia Microbiana , Seguridad de Productos para el Consumidor , Relación Dosis-Respuesta a Droga , Escherichia coli O157/crecimiento & desarrollo , Aromatizantes/farmacología , Manipulación de Alimentos/métodos , Microbiología de Alimentos , Calor , HumanosRESUMEN
This study investigated the efficacy of plant-derived antimicrobials, namely, trans-cinnamaldehyde, ß-resorcylic acid, carvacrol, thymol, and eugenol or their combination, in increasing the sensitivity of Salmonella Typhimurium DT104 to five antibiotics. The subinhibitory concentrations of each antimicrobial or their combination containing concentrations lower than the individual subinhibitory concentrations were added to tryptic soy broth supplemented with antibiotics at their respective break points for resistance. Salmonella Typhimurium DT104 was inoculated into tryptic soy broth at ~6 log CFU/mL, and growth (optical density at 600 nm) was determined before and after incubation at 37° C for 24 hours. Appropriate controls were included. Duplicate samples were assayed and the experiment was replicated three times. Trans-cinnamaldehyde increased the sensitivity of Salmonella Typhimurium DT104 (p<0.05) toward all five antibiotics, namely, ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline, thereby making the pathogen susceptible to drugs. Thymol made the pathogen susceptible to all four antibiotics except ampicillin, whereas carvacrol increased the sensitivity to two antibiotics (chloramphenicol and sulfamethoxazole for strain H3380, and streptomycin and sulfamethoxazole for strain 43). The combination of five molecules was more effective than individual ones (p<0.05) in rendering the pathogen susceptible to the antibiotics. Results indicate that these natural molecules individually and synergistically increased the sensitivity of Salmonella Typhimurium DT104 to all the five antibiotics, and justify future studies to control antibiotic resistance of the pathogen in food animals using these plant molecules.
Asunto(s)
Antibacterianos/administración & dosificación , Antiinfecciosos/administración & dosificación , Farmacorresistencia Bacteriana/efectos de los fármacos , Resistencia a Múltiples Medicamentos/efectos de los fármacos , Plantas/química , Salmonella typhimurium/efectos de los fármacos , Acroleína/administración & dosificación , Acroleína/análogos & derivados , Ampicilina/administración & dosificación , Cloranfenicol/administración & dosificación , Cimenos , Eugenol/administración & dosificación , Hidroxibenzoatos/administración & dosificación , Pruebas de Sensibilidad Microbiana , Monoterpenos/administración & dosificación , Estreptomicina/administración & dosificación , Sulfametoxazol/administración & dosificación , Tetraciclina/administración & dosificación , Timol/administración & dosificaciónRESUMEN
Salmonella Enteritidis is a major foodborne pathogen for which chickens serve as reservoir hosts. Reducing Salmonella Enteritidis carriage in chickens would reduce contamination of poultry meat and eggs with this pathogen. We investigated the prophylactic efficacy of feed supplemented with caprylic acid (CA), a natural, generally recognized as safe eight-carbon fatty acid, for reducing Salmonella Enteritidis colonization in chicks. One hundred commercial day-old chicks were randomly divided into five groups of 20 birds each: CA control (no Salmonella Enteritidis, CA), positive control (Salmonella Enteritidis, no CA), negative control (no Salmonella Enteritidis, no CA), and 0.7 or 1% CA. Water and feed were provided ad libitum. On day 8, birds were inoculated with 5.0 log CFU of Salmonella Enteritidis by crop gavage. Six birds from each group were euthanized on days 1, 7, and 10 after challenge, and Salmonella Enteritidis populations in the cecum, small intestine, cloaca, crop, liver, and spleen were enumerated. The study was replicated three times. CA supplementation at 0.7 and 1% consistently decreased Salmonella Enteritidis populations recovered from the treated birds. Salmonella Enteritidis counts in the tissue samples of CA-treated chicks were significantly lower (P < 0.05) than those of control birds on days 7 and 10 after challenge. Feed intake and body weight did not differ between the groups. Histological examination revealed no pathological changes in the cecum and liver of CA-supplemented birds. The results suggest that prophylactic CA supplementation through feed can reduce Salmonella Enteritidis colonization in day-old chicks and may be a useful treatment for reducing Salmonella Enteritidis carriage in chickens.