RESUMO
Lactobacilli have been shown to promote health functions. In this study, we analyzed the mechanism by which four different strains of probiotics affected innate immunity, such as regulation of ROS, cytokines, phagocytosis, bactericidal activity, signaling by NF-κB pp65, and TLR2 activation. The production of ROS was dependent on the concentration and species of Lactobacillus. The results obtained from the tested strains (Lactobacillus rhamnosus GG, L. rhamnosus KLSD, L. helveticus IMAU70129, and L. casei IMAU60214) showed that strains induced early proinflammatory cytokines such as IL-8,TNF-α, IL-12p70, and IL-6. However, IL-1ß expression was induced only by L. helveticus and L. casei strains (after 24 h stimulation). Phagocytosis and bactericidal activity of macrophages against various pathogens, such as S. aureus, S. typhimurium, and E. coli, were increased by pretreatment with Lactobacillus. The nuclear translocation NF-κB pp65 and TLR2-dependent signaling were also increased by treatment with the probiotics. Taken together, the experiments demonstrate that probiotic strains of Lactobacillus exert early immunostimulatory effects that may be directly linked to the initial inflammation of the response of human macrophages.
Assuntos
Imunidade Inata , Inflamação , Lactobacillus/imunologia , Ativação de Macrófagos , Probióticos , Células Cultivadas , Citocinas/biossíntese , Citocinas/imunologia , Humanos , Interleucina-12/biossíntese , Interleucina-6/biossíntese , Interleucina-8/biossíntese , Lactobacillus/fisiologia , Lacticaseibacillus rhamnosus/imunologia , Lacticaseibacillus rhamnosus/fisiologia , NF-kappa B/metabolismo , Fagocitose , Transdução de Sinais , Fator de Necrose Tumoral alfa/biossínteseRESUMO
The effects of heat treatments of milk and whey prior to lactose hydrolysis with Kluyveromyces lactis beta-galactosidase were studied. It was observed that heat treatment of milk significantly increases lactase activity, with a maximum activity increase found when milk was heated at 55 degrees C. In whey from 55 up to 75 degrees C, beta-galactosidase activity decreased slightly. Nevertheless, heating whey at 85 degrees C for 30 min raised the rate of hydrolysis significantly. Electrophoretic patterns and UV spectra proved that the activity change correlated with milk protein denaturation, particularly that of beta-lactoglobulin. Heating whey permeate did not increase the enzyme activity as heating whole whey; but heating whey prior to ultrafiltration also resulted in enzyme activation. Measurement of free sulfhydryl (SH) groups in both whey and heated whey permeate showed that the liberation of free SH is highly correlated to the change of the activity. Furthermore, this activation can be reversed by oxidizing the reactive sulfhydryl groups, proving that the observed effect may be related to the release of free SH to the medium, rather than to the denaturation of a thermolabile protein inhibitor.
Assuntos
Temperatura Alta , Leite/enzimologia , Compostos de Sulfidrila/metabolismo , beta-Galactosidase/metabolismo , Animais , Hidrólise , Lactase , Proteínas do Leite/química , Proteínas do Leite/metabolismo , Desnaturação Proteica , Compostos de Sulfidrila/análise , Compostos de Sulfidrila/farmacologia , Proteínas do Soro do LeiteRESUMO
The flavor of alcoholic beverages is a consequence of a complex mixture of many compounds, including small concentrations of some volatile metabolites known as congeners, which are produced by the yeast during the fermentation. The more important compounds are those that can be found in all the alcoholic beverages in different concentrations, and they can be grouped on the following chemical species: higher alcohols, esters, and carboniles. In the current paper the biochemical pathways that produce these compounds from the raw materials are reviewed. Research done in this field has led to a more complete knowledge concerning to organoleptic profiles of alcoholic beverages and to a better control for the production of the final product.
Assuntos
Etanol/metabolismo , Saccharomyces cerevisiae/metabolismo , Acetaldeído/metabolismo , Bebidas Alcoólicas , Álcoois/metabolismo , Aminoácidos/metabolismo , Metabolismo dos Carboidratos , Ésteres/metabolismo , Fermentação , Cetonas/metabolismoRESUMO
The role of the enzymes uridine-5'-diphospho-(UDP) glucose pyrophosphorylase and UDP galactose 4-epimerase in exopolysaccharide production of Gal- ropy and non-ropy strains of Streptococcus thermophilus in a batch culture was investigated. Growth of the ropy and non-ropy strains was accompanied by total release of the galactose moiety from lactose hydrolysis in modified Bellinker broth with lactose as the only carbon source. This was associated with a greater exopolysaccharide production by the ropy strain. The polymer produced by both strains in cultures with lactose or glucose as carbon sources contained glucose, galactose and rhamnose, indicating that glucose was used as a carbon source for bacterial growth and for exopolysaccharide formation. UDP-glucose pyrophosphorylase activity was associated with polysaccharide production during the first 12 h in a 20 h culture in the ropy strain, but not in the non-ropy strain. UDP-galactose 4-epimerase was not associated with exopolysaccharide synthesis in any strain. The evidence presented suggests that the glucose moiety from lactose hydrolysis is the source of sugar for heteropolysaccharide synthesis, due to a high UDP-glucose pyrophosphorylase activity.
Assuntos
Lactose/metabolismo , Polissacarídeos Bacterianos/biossíntese , UDPglucose 4-Epimerase/metabolismo , UTP-Glucose-1-Fosfato Uridililtransferase/metabolismo , Iogurte , Galactose/biossíntese , Genótipo , FenótipoRESUMO
The commercial sources of microbial beta-galactosidases (lactases) include the yeasts species Kluyveromyces marxianus, Kluyveromyces lactis and Candida kefyr which are used to hydrolyse lactose in milk due to their optimum pH. On the other hand, lactases obtained from the moulds Aspergillus niger and Aspergillus oryzae have an acid optimum pH and therefore are used to hydrolyse lactose in whey to obtain whey syrups to be used as raw materials in the food industry. The lactose intolerance problem has led to many studies concerning lactose hydrolysis by means of these microbial enzymes to obtain milk suitable for people with lactose maldigestion and special diets for ill persons, elderly population and intolerant babies due to secondary deficiency of lactose. Most industries obtain hydrolyzed lactose milk with free enzyme; however, there are some developments of immobilized lactase catalysts which are being used mainly in whey.
Assuntos
Laticínios , Lactose/metabolismo , Leite/enzimologia , beta-Galactosidase/metabolismo , Animais , Hidrólise , Leveduras/enzimologiaRESUMO
A mixture of Kluyveromyces fragilis biomass and coagulated whey proteins was obtained by fermentation of whole whey. This product had a chemical composition similar to that of washed products reported in the literature with high-crude protein and low-ash contents. The product had a high content of sulphur-containing amino acids and tryptophan, which are usually limiting in yeast biomass. Lysine content was inexplicably lower than the expected value, being the limiting amino acid in this case. The chemical score of the protein was 91%. From the biomass-whey proteins product a protein isolate could be recovered with a yield of 80%. The protein content of the isolate was 75%, and the nucleic acids were reduced by 90.8%. The cell-wall debris were also considerably reduced.