RESUMEN
Proteins are indispensable components of living organisms, which are derived mainly from diet through metabolism. Dietary proteins are degraded by endogenous digestive enzymes to di- or tripeptides and free amino acids (AAs) in the small intestine lumen and then absorbed into blood and lymph through intestinal epithelial cells via diverse transporters. Microorganisms are involved not only in the proteins' catabolism, but also the AAs, especially essential AAs, anabolism. Probiotics regulate these processes by providing exogenous proteases and AAs and peptide transporters, and reducing hazardous substances in the food and feed. But the core mechanism is modulating of the composition of intestinal microorganisms through their colonization and exclusion of pathogens. The other effects of probiotics are associated with normal intestinal morphology, which implies that the enterocytes secrete more enzymes to decompose dietary proteins and absorb more nutrients.
Asunto(s)
Aminoácidos/metabolismo , Proteínas en la Dieta/metabolismo , Enterocitos/metabolismo , Microbioma Gastrointestinal/fisiología , Absorción Intestinal/fisiología , Probióticos/metabolismo , Amoníaco/metabolismo , Alimentación Animal/análisis , Alimentación Animal/microbiología , Animales , Transporte Biológico/fisiología , Proteínas Portadoras/clasificación , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Proteínas en la Dieta/administración & dosificación , Enterocitos/citología , Expresión Génica , Humanos , Oligopéptidos/metabolismo , Probióticos/análisis , Probióticos/farmacologíaRESUMEN
Dietary proteins are linked to the pathogenic Escherichia coli (E. coli) through the intestinal tract, which is the site where both dietary proteins are metabolized and pathogenic E. coli strains play a pathogenic role. Dietary proteins are degraded by enzymes in the intestine lumen and their metabolites are transferred into enterocytes to be further metabolized. Seven diarrheagenic E. coli pathotypes have been identified, and they damage the intestinal epithelium through physical injury and effector proteins, which lead to inhibit the digestibility and absorption of dietary proteins in the intestine tract. But the increased tryptophan (Trp) content in the feed, low-protein diet or milk fractions supplementation is effective in preventing and controlling infections by pathogenic E. coli in the intestine.
Asunto(s)
Diarrea/metabolismo , Proteínas en la Dieta/metabolismo , Escherichia coli Enteropatógena/metabolismo , Escherichia coli Enterotoxigénica/metabolismo , Infecciones por Escherichia coli/metabolismo , Escherichia coli Shiga-Toxigénica/metabolismo , Alimentación Animal/análisis , Animales , Diarrea/dietoterapia , Diarrea/microbiología , Diarrea/patología , Dieta con Restricción de Proteínas/métodos , Proteínas en la Dieta/uso terapéutico , Escherichia coli Enteropatógena/efectos de los fármacos , Escherichia coli Enteropatógena/patogenicidad , Escherichia coli Enterotoxigénica/efectos de los fármacos , Escherichia coli Enterotoxigénica/patogenicidad , Infecciones por Escherichia coli/dietoterapia , Infecciones por Escherichia coli/microbiología , Infecciones por Escherichia coli/patología , Microbioma Gastrointestinal , Humanos , Absorción Intestinal/efectos de los fármacos , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiología , Mucosa Intestinal/patología , Proteínas de la Leche/metabolismo , Proteínas de la Leche/uso terapéutico , Escherichia coli Shiga-Toxigénica/efectos de los fármacos , Escherichia coli Shiga-Toxigénica/patogenicidad , Triptófano/metabolismo , Triptófano/farmacologíaRESUMEN
Corncob residue, a waste in xylose or xylitol production, was utilized to produce 2,3-butanediol (2,3-BD) via simultaneous saccharification and fermentation (SSF). This study developed the optimal conditions for production of 2,3-BD by using a heat-resistant strain, Enterobacter cloacae UV4, to perform SSF of the corncob residue. Urea, lactic acid, sodium citrate, and MgSO4 , selected by the Plackett-Burman experiment, were determined to be significant independent variables to conduct the response surface experiment. With the optimized medium, a total production of 28.923 g/L for 2,3-BD and acetoin (BA) was obtained at 60 H. Furthermore, 43.162 g/L of BA production and 0.553 g/L/H of productivity were obtained by fed-batch SSF, which was 0.424 g diol/g consumed corncob residue. The results suggest that the waste corncob residue could be used as an available substrate for the production of 2,3-BD by E. cloacae UV4, as well as a potential resource to improve the economics of microbial compound production.