RESUMO
Seed oils from oleaginous plants are rich in fatty acids (FAs) that play important roles in the health of the consumers. Recent studies indicate that FA also can play an important role in communication and regulation of virulence in bacteria. Nevertheless, evidence demonstrating protection against bacterial infections mediated by their quorum sensing inhibition (QSI) activity is scarce. In this study, sunflower, chia, and amaranth oils, were assayed for their QSI capacity by inhibiting violacein production and alkaline exoprotease activity of Chromobacterium violaceum. In vitro assays revealed that the oils exhibited QSI activities, whereas in vivo they delayed death of mice inoculated intraperitoneally with the bacterium. Gas chromatography coupled with mass spectrometry analysis of the oils indicated the presence of saturated FA (SAFA) and unsaturated FA as main components. Through a structure-activity relationship study of free FAs, bactericidal effect was identified mainly for polyunsaturated FAs, whereas QSI activity was restricted to SAFA of chains 12-18 carbon atoms in length. These data correlate with a possible interaction suggested by molecular docking analysis of lauric, myristic, and stearic acids with the CviR protein. Our study highlights the antiquorum sensing potential of SAFA, which may be future antivirulence therapeutic agents for the treatment of bacterial infections.
Assuntos
Antibacterianos/farmacologia , Chromobacterium/efeitos dos fármacos , Ácidos Graxos/farmacologia , Magnoliopsida/química , Óleos de Plantas/farmacologia , Percepção de Quorum/efeitos dos fármacos , Sementes/química , Amaranthus/química , Animais , Antibacterianos/química , Antibacterianos/uso terapêutico , Infecções Bacterianas/tratamento farmacológico , Infecções Bacterianas/microbiologia , Chromobacterium/metabolismo , Chromobacterium/patogenicidade , Exopeptidases/metabolismo , Ácidos Graxos/química , Ácidos Graxos/uso terapêutico , Ácidos Graxos Insaturados/química , Ácidos Graxos Insaturados/farmacologia , Ácidos Graxos Insaturados/uso terapêutico , Cromatografia Gasosa-Espectrometria de Massas , Helianthus/química , Indóis/metabolismo , Camundongos , Simulação de Acoplamento Molecular , Óleos de Plantas/química , Óleos de Plantas/uso terapêutico , Salvia/química , Relação Estrutura-Atividade , Fatores de Virulência/metabolismoRESUMO
Digestive capabilities, such as the rates nutrient hydrolysis and absorption, may affect energy intake and ultimately feeding behavior. In birds, a high diversity in gut biochemical capabilities seems to support the existence of a correlation between the morphology and physiology of the intestinal tract and chemical features of the natural diet. However, studies correlating the activity of digestive enzymes and the feeding habits at an evolutionary scale are scarce. We investigated the effect of dietary habits on the digestive physiological characteristics of eight species of passerine birds from Central Chile. The Order Passeriformes is a speciose group with a broad dietary spectrum that includes omnivorous, granivorous and insectivorous species. We measured the activity of three enzymes: maltase, sucrase and aminopeptidase-N. Using an autocorrelation analysis to remove the phylogenetic effect, we found that dietary habits had no effect on enzymatic activity. However, we found that granivorous and omnivorous species had higher levels of disaccharidase activities and insectivores had the lowest. The major difference in enzymatic activity found at the inter-specific level, compared to the reported lower magnitude of enzyme modulation owing to dietary acclimation, suggests that these differences to some extent have a genetic basis. However, the lack of a clear association between diet categories and gut physiology suggested us that dietary categorizations do not always reflect the chemical composition of the ingested food.
Assuntos
Digestão/fisiologia , Dissacaridases/metabolismo , Exopeptidases/metabolismo , Comportamento Alimentar/fisiologia , Intestinos/enzimologia , Passeriformes/fisiologia , alfa-Glucosidases/metabolismo , Animais , Índice de Massa Corporal , Chile , Dieta , Filogenia , Especificidade da Espécie , Sacarase/metabolismoRESUMO
Digestive capabilities, such as the rates nutrient hydrolysis and absorption, may affect energy intake and ultimately feeding behavior. In birds, a high diversity in gut biochemical capabilities seems to support the existence of a correlation between the morphology and physiology of the intestinal tract and chemical features of the natural diet. However, studies correlating the activity of digestive enzymes and the feeding habits at an evolutionary scale are scarce. We investigated the effect of dietary habits on the digestive physiological characteristics of eight species of passerine birds from Central Chile. The Order Passeriformes is a speciose group with a broad dietary spectrum that includes omnivorous, granivorous and insectivorous species. We measured the activity of three enzymes: maltase, sucrase and aminopeptidase-N. Using an autocorrelation analysis to remove the phylogenetic effect, we found that dietary habits had no effect on enzymatic activity. However, we found that granivorous and omnivorous species had higher levels of disaccharidase activities and insectivores had the lowest. The major difference in enzymatic activity found at the inter-specific level, compared to the reported lower magnitude of enzyme modulation owing to dietary acclimation, suggests that these differences to some extent have a genetic basis. However, the lack of a clear association between diet categories and gut physiology suggested us that dietary categorizations do not always reflect the chemical composition of the ingested food.
Assuntos
Animais , Digestão/fisiologia , Dissacaridases/metabolismo , Exopeptidases/metabolismo , Comportamento Alimentar/fisiologia , Intestinos/enzimologia , Passeriformes/fisiologia , alfa-Glucosidases/metabolismo , Índice de Massa Corporal , Chile , Dieta , Filogenia , Especificidade da Espécie , Sacarase/metabolismoRESUMO
In soil ecosystems, bacteria must cope with predation activity, which is attributed mainly to protists. The development of antipredation strategies may help bacteria maintain higher populations and persist longer in the soil. We analyzed the interaction between the root-colonizing and biocontrol strain Pseudomonas fluorescens CHA0 and three different protist isolates (an amoeba, a flagellate, and a ciliate). CHA0 produces a set of antibiotics, HCN, and an exoprotease. We observed that protists cannot grow on CHA0 but can multiply on isogenic regulatory mutants that do not produce the extracellular metabolites. The in vitro responses to CHA0 cells and its exoproducts included growth inhibition, encystation, paralysis, and cell lysis. By analyzing the responses of protists to bacterial supernatants obtained from different isogenic mutants whose production of one or more exometabolites was affected and also to culture extracts with antibiotic enrichment, we observed different contributions of the phenolic antifungal compound 2,4-diacetylphloroglucinol (DAPG) and the extracellular protease AprA to CHA0 toxicity for protists and to the encystation-reactivation cycle. The grazing pressure artificially produced by a mixture of the three protists in a microcosm system resulted in reduced colonization of cucumber roots by a regulatory isogenic CHA0 mutant unable to produce toxins. These results suggest that exometabolite production in biocontrol strain CHA0 may contribute to avoidance of protist grazing and help sustain higher populations in the rhizosphere, which may be a desirable and advantageous trait for competition with other bacteria for available resources.
Assuntos
Antibacterianos/farmacologia , Eucariotos/efeitos dos fármacos , Exopeptidases/farmacologia , Cianeto de Hidrogênio/farmacologia , Comportamento Predatório/efeitos dos fármacos , Pseudomonas fluorescens/metabolismo , Animais , Antibacterianos/metabolismo , Antibiose , Contagem de Colônia Microbiana , Cucumis sativus/microbiologia , Eucariotos/classificação , Eucariotos/microbiologia , Eucariotos/fisiologia , Exopeptidases/metabolismo , Cianeto de Hidrogênio/metabolismo , Controle Biológico de Vetores , Doenças das Plantas/microbiologia , Raízes de Plantas/microbiologia , Comportamento Predatório/fisiologia , Pseudomonas fluorescens/genética , Solo/parasitologia , Microbiologia do SoloRESUMO
We have partially characterized some biochemical properties of exoproteinases secreted into culture medium by the mycelial form of Paracoccidioides brasiliensis, a dimorphic fungus that causes human disease in Latin America. Proteinase activity was analyzed in solid- and liquid-phase systems using zymography and Azocoll, respectively. Minimal or no gelatinase activity was observed by zymography in the crude filtrates among proteins with a relative mobility greater than 200 kDa. When the crude filtrate was fractionated by isoelectric focusing or ion exchange chromatography, we observed striking activation of gelatinases, both those of high apparent molecular mass and alkaline isoelectric points (pI), as well as those of lower molecular mass and acidic pI. The apparent high molecular mass gelatinases, pI 10, showed optimal activity at pH 7.0. They were totally inhibited by phenylmethylsulfonylfluoride and partially inhibited by incubation with previously neutralized fractions of pI 5.4 and 6.1. The latter inhibition could be reversed by exposure to 10% isopropanol. These results provide evidence of regulatory mechanisms controlling proteinase activity in secreted proteins. The principal mechanism appears to be the formation of reversible complexes with endogenous inhibitors.
Assuntos
Exopeptidases/metabolismo , Proteínas Fúngicas , Glicoproteínas/metabolismo , Oligossacarídeos/metabolismo , Paracoccidioides/enzimologia , Inibidores de Proteases/farmacologia , Serina Endopeptidases/metabolismo , Antígenos de Fungos/metabolismo , Meios de Cultura , Regulação Enzimológica da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Concentração de Íons de Hidrogênio , Focalização Isoelétrica , Paracoccidioides/crescimento & desenvolvimentoRESUMO
The exoprotease from Oenococcus oeni produced in stress conditions was purified to homogeneity in two steps, a 14-fold increase of specific activity and a 44% recovery of proteinase activity. The molecular mass was estimated to be 33.1 kDa by gel filtration and 17 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). These results suggest that the enzyme is a dimer consisting of two identical subunits. Optimal conditions for activity on grape juice were 25 degrees C and a pH of 4.5. Incubation at 70 degrees C, 15 min, destroyed proteolytic activity. The SDS-PAGE profile shows that the enzyme was able to degrade the grape juice proteins at a significantly high rate. The activity at low pH and pepstatin A inhibition indicate that this enzyme is an aspartic protease. The protease activity increases at acidic pH suggesting that it could be involved in the wine elaboration.