RESUMO
Bifidobacteria are predominant in the lumen of the large intestine and confer various health benefits on the host. They are also used in the preparation of new fermented milks (bioyogurts) or added to conventional yogurt to generate probiotic effects. The colonization of the gut by bacteria tends to be host specific due partly to the way in which bacteria adhere to the intestinal wall. Using a homologous strain of Bifidobacterium animalis in an experimental mouse model, we analyzed by immunofluorescence labelled-bacteria and transmission electronic microscopy the importance of the bacterial interaction with epithelial an immune cells associated to the gut, and the effect of feeding of B. animalis in the immune response. It was able to adhere and interact with both small and large intestine. In spite of this interaction with the gut, no modifications in the immune state (secretory or systemic response) were observed. A heterologous strain of Bifidobacterium adolescentis from human faeces, was neither incapable of binding to the intestine, nor influence the immune system activation, when it was administered during 2, 5 or 7 consecutive days; we believe that using a homologous strain, oral tolerance is developed even when the microorganism interacts with the immune cells associated with the intestine. However, we cannot ignore the beneficial effect of these microorganisms, especially in the prevention of intestinal infections. We think that this property exerted by bifidobacteria is more related to other mechanisms such as competitive inhibition, acid production or others, than enhancement of the immune state. (AU)
Assuntos
RESEARCH SUPPORT, NON-U.S. GOVT , Bifidobacterium/imunologia , Intestinos/imunologia , Intestinos/microbiologia , Aderência Bacteriana , Bifidobacterium/metabolismo , Bifidobacterium/ultraestrutura , Células Epiteliais/microbiologia , Células Epiteliais/ultraestrutura , Fezes/microbiologia , Imunidade nas Mucosas , Imunoglobulina A/análise , Intestinos/ultraestrutura , Macrófagos Peritoneais/fisiologia , Camundongos , Camundongos Endogâmicos BALB C , Fagocitose , Especificidade da EspécieRESUMO
Bifidobacteria are predominant in the lumen of the large intestine and confer various health benefits on the host. They are also used in the preparation of new fermented milks (bioyogurts) or added to conventional yogurt to generate probiotic effects. The colonization of the gut by bacteria tends to be host specific due partly to the way in which bacteria adhere to the intestinal wall. Using a homologous strain of Bifidobacterium animalis in an experimental mouse model, we analyzed by immunofluorescence labelled-bacteria and transmission electronic microscopy the importance of the bacterial interaction with epithelial an immune cells associated to the gut, and the effect of feeding of B. animalis in the immune response. It was able to adhere and interact with both small and large intestine. In spite of this interaction with the gut, no modifications in the immune state (secretory or systemic response) were observed. A heterologous strain of Bifidobacterium adolescentis from human faeces, was neither incapable of binding to the intestine, nor influence the immune system activation, when it was administered during 2, 5 or 7 consecutive days; we believe that using a homologous strain, oral tolerance is developed even when the microorganism interacts with the immune cells associated with the intestine. However, we cannot ignore the beneficial effect of these microorganisms, especially in the prevention of intestinal infections. We think that this property exerted by bifidobacteria is more related to other mechanisms such as competitive inhibition, acid production or others, than enhancement of the immune state.
Assuntos
Bifidobacterium/imunologia , Intestinos/imunologia , Intestinos/microbiologia , Aderência Bacteriana , Bifidobacterium/metabolismo , Bifidobacterium/ultraestrutura , Células Epiteliais/microbiologia , Células Epiteliais/ultraestrutura , Especificidade da Espécie , Fezes/microbiologia , Imunidade nas Mucosas , Imunoglobulina A/análise , Intestinos/ultraestrutura , Camundongos , Camundongos Endogâmicos BALB C , Macrófagos Peritoneais/fisiologia , FagocitoseRESUMO
AIMS: To study the influence of pH, temperature and culture medium on the growth and bacteriocin production by vaginal Lactobacillus salivarius subsp. salivarius CRL 1328. METHODS AND RESULTS: The study was performed using a complete factorial experimental design. Lactobacillus salivarius was cultivated in LAPTg and MRS broths, adjusted to specific initial pH, and at different temperatures of incubation. The growth, which was evaluated by the Gompertz model, was higher in MRS broth than in LAPTg broth. The initial pH of the culture medium and the temperature had a dramatic effect on the production of bacteriocin. The optimal conditions for bacteriocin production were different to those for optimal growth. The decrease in the pH of the culture medium was parallel to the growth; pH had similar final values in both the MRS and the LAPTg broths. CONCLUSIONS: The optimal growth conditions were recorded in MRS broth, with an initial pH of 6.5 and a temperature of 37 degrees C. The maximum bacteriocin activity was obtained in LAPTg after 6 h at 37 degrees C, and at an initial pH of 6.5 or 8.0. SIGNIFICANCE AND IMPACT OF THE STUDY: The application of a complete factorial design, and the evaluation of the growth parameters through the Gompertz model, enabled a rapid and simultaneous exploration of the influence of pH, temperature and growth medium on both growth and bacteriocin production by vaginal Lact. salivarius CRL 1328.
Assuntos
Bacteriocinas/biossíntese , Lactobacillus/crescimento & desenvolvimento , Vagina/microbiologia , Contagem de Colônia Microbiana , Meios de Cultura , Feminino , Humanos , Concentração de Íons de Hidrogênio , Lactobacillus/metabolismo , TemperaturaRESUMO
The aim of this study was to compare the efficacy of conservation by freezing the strains of Haemophilus influenzae at -20 degrees C and -70 degrees C. Skim milk supplemented with glucose, yeast extract and glycerol allowed highest viability of H. influenzae both at -20 degrees C and -70 degrees C from the media analyzed. Trypticase soy broth and brain heart infusion broth supplemented with glycerol, allowed excellent recovery. Use of cotton swaps as supporting material, with or without addition of cryoprotective agents, did not modify H. influenzae viability after six months of storage. Concentration of the initial inoculum positively affected viability when stored at -20 degrees C. Initial concentration did not influence survival after storage at -70 degrees C. Thawing at room temperature should not exceed 3 h as to get highest survival percentage.
Assuntos
Criopreservação/métodos , Haemophilus influenzae , Crioprotetores/farmacologia , Meios de Cultura , Haemophilus influenzae/efeitos dos fármacos , Humanos , Fatores de TempoRESUMO
The effect of estrogen on the microbial colonization of the urogenital tract is widely discussed, mainly in regard to women with a high incidence of Urinary Tract Infections (UTI). The aim of this work was to study the effect of estradiol on the microbial colonization of lactobacilli and E. coli in mice. Female BALB/c mice were intramuscularly (i.m.) treated with beta-estradiol (one or three doses). The next day, L. fermentum was inoculated intraurethrally with three doses of 10(7) CFU (Colony Forming Units). Later, mice were challenged with uropathogenic E. coli (1 x 10(8) CFU). The hormone levels in sera increased to values 10 times higher than in control animals. Increased differentiation of desquamated vaginal cells and keratinization of the vaginal surface were also observed. The hormonal treatment produced an increased E. coli colonization in the whole tract and a higher level of L. fermentum in kidneys on the 6th day. In mice treated with hormones and lactobacilli, one dose of estradiol was enough to protect animals against the challenge with E. coli. Three doses of estradiol produced a more pronounced protection with a lower number of E. coli. No histological modifications were produced by L.fermentum, while lymphocytic proliferation at submucosal level was observed in E. coli-challenged animals.
Assuntos
Escherichia coli/efeitos dos fármacos , Estradiol/farmacologia , Lactobacillus/efeitos dos fármacos , Sistema Urogenital/microbiologia , Animais , Escherichia coli/crescimento & desenvolvimento , Estradiol/sangue , Feminino , Lactobacillus/crescimento & desenvolvimento , Camundongos , Camundongos Endogâmicos BALB C , Sistema Urogenital/anatomia & histologia , Vagina/citologia , Vagina/efeitos dos fármacosRESUMO
beta-Lactamase was isolated from Neisseria gonorrhoeae, obtained from male patients with gonococcic urethritis. Biochemical properties of the enzyme were studied. The enzyme was purified 38-fold by ammonium sulphate precipitation and using Sephadex G75 and DEAE-cellulose columns. The purified extract exhibited a single band by polyacrylamide gel electrophoresis. Maximum enzyme activity was obtained at 37 degrees C and pH 7.0-7.2 in 50 mM phosphate buffer. Addition of Ni2+, Fe2+, Fe3+, Mn2+ and p-chloromercurybenzoate to the reaction buffer partially inhibited beta-lactamase activity, whereas Hg2+ and EDTA produced complete inhibition. The molecular weight was estimated to be 35,000 Da and the pI of the enzyme was 5.4.
Assuntos
Proteínas de Bactérias/isolamento & purificação , Gonorreia/microbiologia , Neisseria gonorrhoeae/enzimologia , Uretrite/microbiologia , beta-Lactamases/isolamento & purificação , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/metabolismo , Cátions/farmacologia , Temperatura Alta , Humanos , Concentração de Íons de Hidrogênio , Ponto Isoelétrico , Masculino , Peso Molecular , Desnaturação Proteica , Especificidade por Substrato , Temperatura , Inibidores de beta-Lactamases , beta-Lactamases/metabolismo , Ácido p-Cloromercurobenzoico/farmacologiaRESUMO
Citrate utilization by several homo- and heterofermentative lactobacilli was determined in Kempler and McKay and in calcium citrate media. The last medium with glucose permitted best to distinguish citrate-fermenting lactobacilli. Lactobacillus rhamnosus ATCC 11443, Lactobacillus zeae ATCC 15820 and Lactobacillus plantarum ATCC 8014 used citrate as sole energy source, whereas in the other strains, glucose and citrate were cometabolized. Some lactobacilli strains produced aroma compounds from citrate. Citrate transport experiments suggested that all strains studied presented a citrate transport system inducible by citrate. The levels of induction were variable between several strains. Dot blot experiment showed that lactobacilli do not present an equivalent plasmid coding for citrate permease.
Assuntos
Proteínas de Bactérias , Citratos/metabolismo , Lactobacillus/metabolismo , Acetoína/metabolismo , Transporte Biológico , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Meios de Cultura , Diacetil/metabolismo , Fermentação , Genes Bacterianos , Glucose/metabolismo , Lactobacillus/genética , Lactobacillus/crescimento & desenvolvimento , SimportadoresRESUMO
The structural gene determinants of lactocin 705, a bacteriocin produced by Lactobacillus casei CRL 705, have been amplified from a plasmid of approximately 35 kb and sequenced. Lactocin 705 is a class IIb bacteriocin, whose activity depends upon the complementation of two peptides (705alpha and 705beta) of 33 amino acid residues each. These peptides are synthesized as precursors with signal sequences of the double-glycine type, which exhibited high identities with the leader peptides of plantaricin S and J from Lactobacillus plantarum, brochocin C from Brochotrix campestris, sakacin P from Lactobacillus sake, and the competence stimulating peptides from Streptococcus gordonii and Streptococcus mitis. However, the two mature bacteriocins 705alpha and 705beta do not show significant similarity to other sequences in the databases.
Assuntos
Bacteriocinas/biossíntese , Bacteriocinas/genética , Genes Bacterianos , Lacticaseibacillus casei/metabolismo , Sequência de Aminoácidos , Bacteriocinas/química , Bacteriocinas/classificação , Sequência de Bases , Lacticaseibacillus casei/genética , Dados de Sequência Molecular , Peptídeos/síntese química , Peptídeos/química , Plasmídeos/genética , Reação em Cadeia da Polimerase , Análise de Sequência de DNARESUMO
Administration of Lactobacillus reuteri CRL 1098 (10(4) cells/d) to mice for 7 d before inducing hypercholesterolemia (by feeding mice with a fat-enriched diet for the subsequent 7 d) was evaluated. At this low dose, L. reuteri was effective in preventing hypercholesterolemia in mice, producing a 17% increase in the ratio of high-density lipoprotein to low-density lipoprotein. Total cholesterol and triglycerides decreased by 22 and 33%, respectively, in the group that was not fed the lactobacilli. The hypocholesterolemic effect produced by L. reuteri CRL 1098 might be considered as indirect evidence of the permanency of the lactobacilli in the gut.
Assuntos
Hipercolesterolemia/prevenção & controle , Lactobacillus/fisiologia , Probióticos , Animais , Colesterol/sangue , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Gorduras na Dieta/administração & dosagem , Camundongos , Triglicerídeos/sangueRESUMO
Nutrition plays a key role in maintaining the balance of the intestinal microflora. Malnutrition disturbs the ecological barrier and induces histological damage. We evaluated modifications induced by renutrition with nonfat milk (NFM) and Lactobacillus casei administration (for 2 days) on the bacterial gut population and structural and ultrastructural gut modifications in malnourished mice. Balb/c mice suffering from a malnutrition process immediately after weaning (for 21 days) were divided into four groups and were given NFM for 0, 7, 14, and 21 days. Another group was treated in a similar way, but after different periods of NFM administration, mice in this group received L. casei for two consecutive days. All experimental animals were sacrificed by cervical dislocation, and both the microflora and the histological structure of the intestine were studied. In malnourished animals, a decrease in the numbers of Lactobacillus and anaerobic microorganisms was observed, whereas there was an increase in the number of Enterobacteriaceae. In animals treated with NFM and NFM plus L. casei, we could observe an important improvement in the microflora in the small and large intestines but no differences between both treatments. Structural and ultrastructural studies showed a slight improvement 7 days after treatment with NFM, and for 14 and 21 days after renutrition, the mice showed normal intestinal villi, whereas the additional feeding with L. casei for two consecutive days, after different periods of renutrition, yielded an earlier improvement (7 days).