RESUMO
The ban on the use of antibiotics as feed additives for animal growth promotion in the European Union and United States and the expectation of this trend to further expand to other countries in the short term have prompted a surge in probiotic research. Multi-species probiotics including safe and compatible strains with the ability to bind different nutritional lectins with detrimental effects on poultry nutrition could replace antibiotics as feed additives. Lactobacillus salivarius LET201, Lactobacillus reuteri LET210, Enterococcus faecium LET301, Propionibacterium acidipropionici LET103 and Bifidobacterium infantis CRL1395 have proved to be compatible as evaluated through three different approaches: the production and excretion of antimicrobial compounds, growth inhibition by competition for essential nutrients and physical contact, and a combination of both. The safety of P. acidipropionici LET103 was confirmed, since no expression of virulence factors or antibiotic resistance was detected. The innocuity of E. faecium LET301 should be further evaluated, since the presence of genes coding for certain virulence factors (gelE, efaAfm and efaAfs) was observed, albeit no expression of gelE was previously detected for this strain and there are no reports of involvement of efaAfm in animal pathogenicity. Finally, a combination of the five strains effectively protected intestinal epithelial cells of broilers from the cytotoxicity of mixtures of soybean agglutinin, wheat germ agglutinin and concanavalin A. To our knowledge, this is the first time that a combination of strains is evaluated for their protection against lectins that might be simultaneously present in poultry feeds.
Assuntos
Anti-Infecciosos/metabolismo , Bifidobacterium longum subspecies infantis/metabolismo , Enterococcus faecium/metabolismo , Lactobacillus/metabolismo , Doenças das Aves Domésticas/prevenção & controle , Probióticos/farmacologia , Propionibacterium/metabolismo , Animais , Antibiose , Bifidobacterium longum subspecies infantis/genética , Bifidobacterium longum subspecies infantis/crescimento & desenvolvimento , Bifidobacterium longum subspecies infantis/patogenicidade , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Concanavalina A/toxicidade , Farmacorresistência Bacteriana , Enterococcus faecium/genética , Enterococcus faecium/crescimento & desenvolvimento , Enterococcus faecium/patogenicidade , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/fisiologia , Lactobacillus/genética , Lactobacillus/crescimento & desenvolvimento , Lactobacillus/patogenicidade , Lectinas/metabolismo , Modelos Teóricos , Lectinas de Plantas/toxicidade , Probióticos/efeitos adversos , Propionibacterium/genética , Propionibacterium/crescimento & desenvolvimento , Propionibacterium/patogenicidade , Ligação Proteica , Proteínas de Soja/toxicidade , Virulência , Fatores de Virulência/genética , Aglutininas do Germe de Trigo/toxicidadeRESUMO
Poultry fed on wheat-based diets regularly ingest wheat germ agglutinin (WGA) that has toxic effects in vitro on intestinal epithelial cells (IEC) obtained from 14-d-old broilers. Cytotoxicity and the potential role of 14 intestinal bacterial strains in the removal of bound lectins in epithelial cell cultures were investigated. Cytotoxicity was dependent on time and lectin concentration; the lethal dose (LD50) was 8.36 µg/ml for IEC exposed for 2 h to WGA. Complementary sugars to WGA were detected on the surface of one Enterococcus and 9 Lactobacillus strains isolated from poultry. These strains were evaluated as a lectin removal tool for cytotoxicity prevention. Incubation of lactic acid bacteria with WGA before IEC-lectin interaction caused a substantial reduction in the percentage of cell deaths. The protection was attributed to the amount of lectin bound to the bacterial surfaces and was strain-dependent. L. salivarius LET 201 and L. reuteri LET 210 were more efficient than the other lactic acid bacteria assayed. These results provide a basis for the development of probiotic supplements or cell-wall preparations of selected lactic acid bacteria intended to avoid harmful effects of a natural constituent of the grain in wheat-based diets.
Assuntos
Galinhas/microbiologia , Enterococcus/fisiologia , Enterócitos/efeitos dos fármacos , Lactobacillus/fisiologia , Doenças das Aves Domésticas/prevenção & controle , Aglutininas do Germe de Trigo/toxicidade , Animais , Dieta/efeitos adversos , Dieta/veterinária , Enterococcus/isolamento & purificação , Intestinos/citologia , Intestinos/microbiologia , Lactobacillus/isolamento & purificação , Aves Domésticas/microbiologia , Doenças das Aves Domésticas/induzido quimicamente , Probióticos , Especificidade da EspécieRESUMO
Different studies in animal rearing claim the probiotic potential of species of the genus Propionibacterium. The effects of strains of Propionibacterium acidipropionici isolated from poultry intestine on microbiota activity and intestinal mucosa development were investigated in the early stage of rearing chicks and the safety of the dose used was investigated. The strains P. acidipropionici LET105 and LET107, administered as monoculture to chicks from the 1st to 14th day of life in a daily dose of 106 cfu/ml administered in the drinking water resulted harmless. The animals arrived at the expected weight for age and no differences were observed with respect to the food intake and water consumption related to control without bacteria administration. The analysis of microbiota composition revealed the presence of propionibacteria at the middle and end of the trial only in treated groups. Normal development of lactic acid bacteria and bifidobacteria, and slow colonisation by Bacteroides at the 7th day of the study was observed in the same groups. Analysis of the organic acids concentrations in the caecal content of birds revealed higher lactic acid and lower butyric acid production. Lower short chain fatty acids total concentration than expected during treatment was related to a better development of the gut mucosa. Increase in length of villus-crypt units, goblet cells counts and neutral mucins production were evidenced. Higher mucus secretion produced by dietary supplementation with propionibacteria could provide increased protection against pathogens.
Assuntos
Galinhas/microbiologia , Microbioma Gastrointestinal , Probióticos/farmacologia , Propionibacterium , Ração Animal , Animais , Butiratos/metabolismo , Ceco/imunologia , Ceco/microbiologia , Galinhas/crescimento & desenvolvimento , Galinhas/fisiologia , Dieta/veterinária , Ácidos Graxos Voláteis/metabolismo , Feminino , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Intestinos/imunologia , Intestinos/microbiologia , Ácido Láctico/metabolismo , Distribuição Aleatória , Aumento de Peso/efeitos dos fármacosRESUMO
Bacterial adhesion onto hydroxyapatite is known to depend on the surface properties of both the biomaterial and the bacterial strain, but less is known about the influence of the composition of the aqueous medium. Here, the adhesion of Streptococcus mutans and 3 different Lactobacilli on powdered hydroxyapatite was shown to change with Ca2+ concentration. The effect depends on the surface properties of each strain. Adhesion of Lactobacillus fermentum and salivarius (and of Streptococcus mutans at low Ca2+) was enhanced with increasing Ca2+ concentration. Lactobacillus casei was efficiently removed by adhesion on hydroxyapatite, even without Ca2+ addition, and the effect of this ion was only marginal. The results are interpreted in terms of Ca2+-mediated adhesion, and relative to the hydrophobic properties of each strain and the electrical properties of the bacterial and solid surfaces (electrophoretic mobility).
Assuntos
Aderência Bacteriana/efeitos dos fármacos , Materiais Biocompatíveis/química , Cálcio/farmacologia , Durapatita/química , Lactobacillus/efeitos dos fármacos , Streptococcus mutans/efeitos dos fármacos , Adsorção , Cálcio/química , Eletroforese , Humanos , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Lactobacillus/classificação , Lacticaseibacillus casei/efeitos dos fármacos , Limosilactobacillus fermentum/efeitos dos fármacos , Pós , Saliva/fisiologia , Propriedades de SuperfícieRESUMO
Electrophoretic mobilities of various synthetic and semisynthetic hydroxyapatites (Ca10(PO4)6(OH)2, HAP) suspended in aqueous solutions have been measured as a function of pH and calcium concentration. The studied powders differ in particle size, crystallinity degree and surface contamination (carbonate). When equilibrated in mineral acids or bases, a large plateau of negative mobility is observed in the pH range 5-8, with increasing negative values at higher pH. Only in the case of the sample composed of nanoparticles, positive mobility obtains at pH < 8.9. When Ca2+ is added, positive mobility values are observed for all samples, and a bell-shaped profile results as a function of pH. Two possible models are explored to describe the results: the Nernstian approach, which assumes solubility equilibrium and surface potentials determined by the three potential-determining ions (Ca2+, PO3-4, and OH-), and the surface complexation approach, based on the idea of negligible phase transfer of structural phosphate. The Nernstian model is inadequate, whereas a very simple surface complexation model based on the equations Ca5(PO4)+3 = Ca4(PO4)-3 + Ca2+,Ca4(PO4)-3 + H+ = Ca4(PO4)2(PO4H),Ca5(PO4)+3 + OH- = Ca5(PO4)3(OH),coupled with a very simple electrical double layer, model suffices to reproduce the bell-shaped profile of the mobility as a function of pH in the presence of added calcium salts. The results also show that the sample composed of nanoparticles exchanges ions more easily with the solution, without reaching the solubility equilibrium in the explored timespans. In the presence of soluble phosphate salts, it is postulated that the same surface ensembles define the surface charge, with participation of phosphate as described by the equation Ca5(PO4)+3 + PO3-4 = Ca4(PO4)-3.HAP is just one member of a family of calcium phosphates with different (Ca)/(P) ratios. Electrophoretic mobilities of another member, tricalcium diphosphate, Ca3(PO4)2, were also measured and shown to be described by the same basic model. Comparison with previous literature data shows that the negative plateau in the mobility is a general feature of many HAP samples at low Ca2+, again in agreement with the surface complexation model. FTIR data demonstrates that surface phosphate indeed undergoes protonation, as postulated in the model.
Assuntos
Hidroxiapatitas/química , Cálcio/química , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Pós/química , Propriedades de SuperfícieRESUMO
Different criteria are followed in order to select bacteria to be used in probiotic and symbiotic supplements. A new parameter to choose strains could be fermentation by intestinal bacteria of some complex carbohydrates because they are prebiotics and promote the development of beneficial microorganisms in the intestinal environment. An Enterococcus faecium strain, isolated from the crop of a free-range chicken, was assayed in order to determine the utilization of commercial sugars and/or crude carbohydrate samples from a sugar mill. The production of antimicrobial substances, under these conditions, was also considered. Ent. faecium CRL1385 grew well in the presence of complex carbohydrates and its ability to produce bacteriocin, active against poultry pathogens such as Ent. hirae, Salmonella pullorum and Listeria monocytogenes, was not significantly modified. These results are promising because the trend today is to employ eubiotic or symbiotic products and their use in the poultry industry could be a natural way to protect the flocks against potential pathogens.
Assuntos
Bacteriocinas/biossíntese , Enterococcus faecium/crescimento & desenvolvimento , Oligossacarídeos/metabolismo , Probióticos , Salmonelose Animal/prevenção & controle , Animais , Bacteriocinas/metabolismo , Galinhas/microbiologia , Enterococcus faecium/metabolismo , Salmonella , Fatores de TempoRESUMO
Enterococcus faecium J96 was isolated from a healthy free-range chicken and it inhibited Salmonella Pullorum, in vitro, due to its lactic acid and bacteriocin production. In vivo assays were carried out with 30-h-old broiler chicks. The lactic acid bacteria (approximately 1 x 10(9) cells per chick) were orally administered as preventive and as therapeutic treatments. In the first case they were given to the chicks twice a day for 3 consecutive days. In the second case the lactic bacteria were administered in the same way after a 24-h challenge by Salmonella Pullorum (in both instances the salmonella dose was 1 x 10(5) cells per chick). Cecal contents, liver, and spleens were analyzed and liver and spleen fragments were also fixed in formaldehyde (pH 7.00) in order to determine salmonella translocation. The chickens that were preventively treated with E. faecium J96 survived the Salmonella Pullorum challenge. Those that were infected on the first day and then inoculated with lactic bacteria died 4 days later. Salmonellae were isolated from their livers and spleens. From these results we may conclude that E. faecium J96 can protect newly hatched chicks from Salmonella Pullorum infection but cannot act as a good therapeutic agent.
Assuntos
Galinhas/microbiologia , Enterococcus faecium/fisiologia , Doenças das Aves Domésticas/prevenção & controle , Probióticos/administração & dosagem , Salmonelose Animal/prevenção & controle , Salmonella/crescimento & desenvolvimento , Animais , Translocação Bacteriana , Bacteriocinas/biossíntese , Ceco/microbiologia , Ácido Láctico/metabolismo , Fígado/microbiologia , Fígado/patologia , Doenças das Aves Domésticas/microbiologia , Probióticos/farmacologia , Salmonella/efeitos dos fármacos , Salmonelose Animal/terapia , Baço/microbiologiaRESUMO
Production of antagonistic compounds was studied in a strain of Enterococcus faecium isolated from the intestinal tract of a free-ranging chicken. Production of lactic acid and a bacteriocin was observed in cultures of this bacterium, alone and in mixed culture fermentations with pathogenic Salmonella serotypes (i.e., Gallinarum, Pullorum, Enteritidis, and Typhimurium). Growth inhibition of these avian and human pathogens was observed after 4 h of incubation at 37 degrees C in CAm broth, a medium developed according to the nutrients present in chicken food. The antibacterial action was due to the combined effect of lactic acid and bacteriocin. Accumulation of these metabolites caused both a bacteriostatic and a bactericidal action against the gram-negative bacteria assayed.
Assuntos
Enterococcus faecium , Probióticos , Salmonella , Animais , Bacteriocinas/metabolismo , Galinhas , Enterococcus faecium/metabolismo , Microbiologia de Alimentos , Humanos , Técnicas In Vitro , Ácido Láctico/metabolismoRESUMO
Different physicochemical studies were undertaken with polycrystalline samples of the complex [Cu2(carnosine)2(H2O)2].2H2O. The infrared spectrum was discussed in comparison with that of free carnosine and on the basis of the known structural data. Magnetic susceptibility measurements were performed between 4.2 and 300 K, showing an effective magnetic moment of 1.79 BM. Both the electronic (reflectance) and ESR spectra were compatible with the existence of a dx2-y2 ground state. The axial reversed ESR spectrum could be explained on the basis of a very weak interdimeric coupling mechanism. The electrochemical behavior, investigated by cyclic voltammetry, shows that the complex possesses a very high redox stability. The possible SOD-like activity was tested using the NBT/superoxide reduction assay. The results show a negligible SOD activity.
Assuntos
Carnosina/química , Cobre/química , Eletroquímica , Espectroscopia de Ressonância de Spin Eletrônica , Magnetismo , Oxirredução , Superóxido Dismutase/química , VibraçãoRESUMO
Fermented milk was used as therapy in infantile diarrhoea due to post-gastroenteritis syndrome. This treatment eliminated the disease in 4.0 days (mean value, SD = 2.8; n = 13) and allowed patients to return to free feeding according to their age. The weight percentile variation during treatment with fermented milk (15 days) was higher in the patients showing 3rd degree malnutrition than in other children. Bacteriotherapy can restore faecal flora which has been lowered by diarrhoea. Our results showed that levels higher than 10(6) UFC lactobacilli/g of faeces correlated with a healthy status of the children. Clinical applications of fermented milk with a mixture of Lactobacillus casei and Lactobacillus acidophilus in the prevention of gastrointestinal disorders are possible.
Assuntos
Diarreia Infantil/dietoterapia , Gastroenterite/dietoterapia , Leite , Animais , Diarreia Infantil/microbiologia , Fezes/microbiologia , Fermentação , Gastroenterite/microbiologia , Humanos , Lactente , SíndromeRESUMO
The superoxide-dismutase-like activity of a series of divalent metal saccharinates of general stoichiometry [MII(Sac)2(H2O)4].2H2O (with MII = Mn,Fe,Co,Ni,Cu,Zn) has been investigated using the nitroblue tetrazolium O2- reduction assay. The results show that all these complexes possess the capability to dismutate the superoxide anion generated in the xanthine/xanthine oxidase system. Interestingly, the greatest activity is shown by the corresponding copper complex. The results are discussed and compared with those obtained for native superoxide dismutase, which was tested under the same experimental conditions.
Assuntos
Cátions Bivalentes/metabolismo , Sacarina/metabolismo , Superóxido Dismutase/metabolismo , Cristalização , Nitroazul de Tetrazólio , Oxirredução , Espectrofotometria Infravermelho , Superóxido Dismutase/análiseRESUMO
The inhibitory effect of lactobacilli on growth of Shigella sonnei was studied. The effect was not due to pH alone, as addition of hydrochloric, lactic or acetic acids to culture media did not inhibit the normal growth of the shigellas. The degree of inhibition was measured by disc assay and showed that the inhibitory substance(s) can be extracellular and diffusible, varying the degrees of inhibition depending on the media tested. When broth was inoculated with mixed cultures of Lactobacillus and Shigella strains, the inhibition began at 6 h and the death phase at 9 h. The higher inhibition was produced by the mixture of lactobacilli (35.5 +/- 2.5% at 6 h culture, 57.4 +/- 1.9% at 9 h and 91.2 +/- 1.2% at 14 h). The degree of inhibition was higher when the relationship pathogen : lactobacilli was 1:10(3). The specific growth rate of lactobacilli and shigella was different in pure or mixed cultures. When the lactobacillus alone was grown for 12 h and the shigellas then added, the numbers of shigellas began to decrease immediately at 37 degrees C. This work shows that the Lactobacillus strains employed in fermented milk can be used to inhibit the growth of Sh. sonnei.
Assuntos
Antibiose , Lacticaseibacillus casei/fisiologia , Lactobacillus acidophilus/fisiologia , Shigella sonnei/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Meios de Cultura , Fatores de TempoRESUMO
The protective effect of feeding milk fermented with a mixture of Lactobacillus casei and Lact. acidophilus against Shigella sonnei was studied. There was a 100% survival rate in mice fed for 8 d with fermented milk and then dosed orally with Sh. sonnei. The survival rate in control mice was approximately 60% after 21 d. Colonization of the liver and spleen with Sh. sonnei was markedly inhibited by pretreatment with fermented milk. Differences in cell counts of 2-3 log units between treated and control mice were always obtained, shigellas were not detected in these organs by the 10th day in treated mice, while high levels were maintained in the controls. Higher levels of anti-shigella antibodies were found both in sera and in small intestinal fluid of mice treated with fermented milk, suggesting that the protective immunity could be mediated by the mucosal tissue. These results suggest that milk fermented with Lact. casei and Lact. acidophilus could be used as a prophylactic against gastrointestinal infections by shigellas.
Assuntos
Disenteria Bacilar/imunologia , Lacticaseibacillus casei/fisiologia , Lactobacillus acidophilus/fisiologia , Leite/microbiologia , Shigella sonnei/imunologia , Animais , Anticorpos Antibacterianos/metabolismo , Fermentação , Imunidade Inata , Fígado/microbiologia , Camundongos , Shigella sonnei/crescimento & desenvolvimento , Baço/microbiologiaRESUMO
The inhibitory effect of vanadate species on the enzymatic activity of bovine copper-zinc superoxide dismutase has been investigated at different pH values and vanadium concentrations. A definite inhibitory effect, clearly related to the main negative charge of each of the vanadate solutions, has been found. The results suggest that the origin of the inhibitory effect may be similar to that found for the phosphate ion, i.e., a diminution of the effectiveness of the substrate electronic guidance mechanism by partial neutralization of the charges close to the active site. Under physiological conditions, the inhibitory effect of vanadate is somewhat smaller than the phosphate.