RESUMEN
Although most vitamins are present in a variety of foods, human vitamin deficiencies still occur in many countries, mainly because of malnutrition not only as a result of insufficient food intake but also because of unbalanced diets. Even though most lactic acid bacteria (LAB) are auxotrophic for several vitamins, it is now known that certain strains have the capability to synthesize water-soluble vitamins such as those included in the B-group (folates, riboflavin and vitamin B(12) amongst others). This review article will show the current knowledge of vitamin biosynthesis by LAB and show how the proper selection of starter cultures and probiotic strains could be useful in preventing clinical and subclinical vitamin deficiencies. Here, several examples will be presented where vitamin-producing LAB led to the elaboration of novel fermented foods with increased and bioavailable vitamins. In addition, the use of genetic engineering strategies to increase vitamin production or to create novel vitamin-producing strains will also be discussed. This review will show that the use of vitamin-producing LAB could be a cost-effective alternative to current vitamin fortification programmes and be useful in the elaboration of novel vitamin-enriched products.
Asunto(s)
Lactobacillaceae/metabolismo , Complejo Vitamínico B/biosíntesis , Avitaminosis/prevención & control , Suplementos Dietéticos , Ácido Fólico/biosíntesis , Alimentos Fortificados , Humanos , Probióticos , Riboflavina/biosíntesis , Vitamina B 12/biosíntesisRESUMEN
AIMS: To evaluate the efficiency of the vitamin B(12-)producing Lactobacillus reuteri CRL1098 strain in preventing the symptoms caused by a nutritional cobalamin-deficient diet in pregnant female mice and their weaned offspring. METHODS AND RESULTS: Pregnant female mice were divided into three groups: animals fed with a B(12)-deficient diet (DD), animals fed with DD plus L. reuteri CRL1098 and animals fed with a B(12)-sufficient diet. The animals received the different feedings from the end of gestation up to weaning. At the end of the trials, they and their corresponding offspring were bled to determine haematological, immunological and histological parameters. The administration of the pseudovitamin B(12)-producing strain prevented the symptoms observed in female and weaned young animals fed with a nutritional B(12)-deficient diet. CONCLUSIONS: Our data suggest that the pseudovitamin B(12) produced by L. reuteri CRL1098 is biologically active and effective in preventing the pathologies caused by the nutritional deficiency of B(12) both in pregnant mice and their offspring. SIGNIFICANCE AND IMPACT OF THE STUDY: The ability of L. reuteri CRL1098 to prevent a nutritional vitamin deficiency was demonstrated for the first time. The addition of a GRAS micro-organism to complement the B(12) content in deficient foods is an interesting biotechnological alternative.
Asunto(s)
Limosilactobacillus reuteri/metabolismo , Preñez/fisiología , Probióticos , Vitamina B 12/biosíntesis , Deficiencia de Vitamina B/prevención & control , Alimentación Animal , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Femenino , Fenómenos Fisiologicos Nutricionales Maternos , Ratones , Ratones Endogámicos BALB C , Estado Nutricional , Embarazo , Vitamina B 12/sangre , Aumento de PesoRESUMEN
The citrate metabolism of Lactobacillus helveticus ATCC 15807 was studied under controlled-pH fermentations at pH 4.5 and pH 6.2. The micro-organism was able to co-metabolize citrate and lactose at both pH from the beginning of growth, which enhanced the rate of lactose consumption and lactic acid production, compared with cultures without citrate. The effect of citrate on cell growth was dependent on the balance between the ratio of dissociated to non-dissociated forms of the acetic acid produced and the extra ATP gained by the cells, both facts related to the citrate metabolism. The citrate catabolism determined a change in the fermentation pattern of L. helveticus ATCC 15807 from homolactic to a mixed-acid profile, regardless of the external pH. Within this new fermentation pattern, acetate was the major product formed (13-20 mM), followed by succinate (2.4-3.7 mM), while acetoine, dyacetile or butanediol were not detected. The mixed-acid profile displayed by L. helveticus ATCC 15807 was linked to NADH(2) oxidase activity rather than the acetate kinase enzyme.
Asunto(s)
Ácido Acético/metabolismo , Ácido Cítrico/metabolismo , Lactobacillus helveticus/metabolismo , Ácido Succínico/metabolismo , Acetoína/análisis , Adenosina Trifosfato/biosíntesis , Butileno Glicoles/análisis , Diacetil/análisis , Fermentación , Concentración de Iones de Hidrógeno , Lactobacillus helveticus/crecimiento & desarrollo , Lactosa/metabolismo , Complejos Multienzimáticos/metabolismo , NADH NADPH Oxidorreductasas/metabolismoRESUMEN
AIMS: The objective of this study was to evaluate the effect of bile salts and cholesterol in the lipid profile of Lactobacillus reuteri CRL 1098 and to determine the relationship existing between these changes: the in vitro removal of cholesterol and the tolerance of the cells to acid and cold stress. METHODS AND RESULTS: Lactobacillus reuteri CRL 1098 was grown in the following media: MRS (deMan Rogosa Sharpe; MC, control medium), MB (MC with bile salts), MCH (MC with sterile cholesterol) and MBCH (MC with bile salts and cholesterol). Fatty acids were determined by analytical gas-liquid chromatography, and phospholipids and glycolipids by colorimetric techniques. The cells from different culture media were subjected to cold and acid stress. The MB cultures displayed a decrease in phospholipids and a low ratio of saturated : unsaturated fatty acids. The presence of the unusual C18 : 0,10-OH and C18 : 0,10-oxo fatty acids was the prominent characteristic of the bile salts growing cells. The relative increase in glycolipids and the changes in the fatty acids profiles of the MB cells would be responsible for the cholesterol remotion. The changes induced by bile salts in the lipid profile did not improve the tolerance of L. reuteri CRL 1098 to freezing and acid stress. CONCLUSIONS: The changes in lipid profiles reported in this study would play a key role in the response of Lactobacilli to environmental stress. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides useful information about the effect of bile salts on the cell membrane of L. reuteri, a probiotic enterolactobacillus. The steady-state response of the cells subjected to bile stress seems to be the appropriate model for evaluating the bacterial behaviour in detergent-containing gastrointestinal tracts, where the bile salts stress would presumably be continuous.
Asunto(s)
Ácidos y Sales Biliares/farmacología , Colesterol/farmacología , Lactobacillus/efectos de los fármacos , Lípidos de la Membrana/análisis , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Cromatografía de Gases/métodos , Cromatografía en Capa Delgada/métodos , Frío , Colorimetría/métodos , Medios de Cultivo , Ácidos Grasos/análisis , Glucolípidos/análisis , Concentración de Iones de Hidrógeno , Lactobacillus/metabolismo , Fosfolípidos/análisisRESUMEN
AIMS: The objective of this work was to evaluate the fermentation pattern of and the exopolysaccharide (EPS) production by Lactobacillus helveticus ATCC 15807 in milk batch cultures under controlled pH (4.5, 5.0 and 6.2). METHODS AND RESULTS: EPS concentration was estimated by the phenol/sulphuric acid method and the chemical composition of purified EPS by HPLC. Fermentation products and residual sugars were determined by HPLC and enzymatic methods. The micro-organism shifted from a homofermentative to a heterofermentative pattern, producing acetate (9.5 and 5.8 mmol l(-1)) at pH 5.0 and 6.2, respectively, and acetate (7.1 mmol l(-1)) plus succinate (1.2 mmol l(-1)) at pH 4.5. At pH 5.0 and 6.2, acetate derived from citrate while at pH 4.5 it came from both citrate and pyruvate splitting. The EPS has a MW of 10(5)-10(6) and contains phosphate (81% in average), rhamnose (traces), and glucose and galactose in a ratio of 1 : 1 (pH 6.2) and 2 : 1 (pH 4.5 and 5.0). The highest production (549 mg l(-1)) corresponded to pH 5.0 and the lowest (49 mg l(-1)) to pH 6.2. CONCLUSIONS: The heterofermentative pattern of Lact. helveticus ATCC 15807 was linked to alternative pyruvate pathways and/or citrate metabolism according to the environmental pH. The EPS production was improved under low environmental pH conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides relevant information of the effect of pH on the metabolism of citrate and EPS production by Lact. helveticus. It may contribute to improve technological aspects of ropy and citrate-utilizing lactic acid bacteria.
Asunto(s)
Lactobacillus/crecimiento & desarrollo , Lactobacillus/metabolismo , Polisacáridos Bacterianos/biosíntesis , Animales , Ácido Cítrico/metabolismo , Medios de Cultivo , Fermentación , Concentración de Iones de Hidrógeno , Leche/metabolismo , Ácido Pirúvico/metabolismoRESUMEN
Taurocholic acid transport in Lactobacillus reuteri CRL 1098 was determined. The bile acid is incorporated inside the cells by an active and saturable transport showing a typical kinetics of Michaelis-Menten with values of Km and Vmax of 0.35 mm and 20 mm, respectively.
Asunto(s)
Lactobacillus/metabolismo , Ácido Taurocólico/metabolismo , Transporte Biológico , Medios de Cultivo , Escherichia coli , Cinética , Lactobacillus/enzimología , Lactobacillus/crecimiento & desarrolloRESUMEN
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.
Asunto(s)
Hipercolesterolemia/prevención & control , Lactobacillus/fisiología , Probióticos , Animales , Colesterol/sangre , HDL-Colesterol/sangre , LDL-Colesterol/sangre , Grasas de la Dieta/administración & dosificación , Ratones , Triglicéridos/sangreRESUMEN
Sugar uptake and phosphoenolpyruvate phosphorylation assays have shown that the heterofermentative strain Lactobacillus reuteri CRL 1098, of likely probiotic value, can transport D-fructose through an inducible fructose-specific phosphotransferase system (K(m) 95 microM) and D-glucose mainly through a proton motive force-driven permease. These data open new perspectives for metabolic and regulatory studies in this bacterium.
Asunto(s)
Glucosa/metabolismo , Lactobacillus/enzimología , Proteínas de Transporte de Membrana/metabolismo , Sistema de Fosfotransferasa de Azúcar del Fosfoenolpiruvato/metabolismo , Transporte Biológico , Fructosa/metabolismo , Lactobacillus/crecimiento & desarrollo , Fuerza Protón-MotrizRESUMEN
Swiss Albino mice were fed a diet enriched with fat to produce hypercholesterolemia. The further administration of Lactobacillus reuteri CRL 1098 (10(4) cells/d) to hypercholesterolemic mice for 7 d decreased total cholesterol by 38%, producing serum cholesterol concentrations similar to that of the control group (67.4 mg/ml). This low dose of L. reuteri caused a 40% reduction in triglycerides and a 20% increase in the ratio of high density lipoprotein to low density lipoprotein without bacterial translocation of the native microflora into the spleen and liver. These data suggest that L. reuteri CRL 1098 is an effective hypocholesterolemic adjuvant at a low cell concentration for mice.
Asunto(s)
Hipercolesterolemia/terapia , Lactobacillus , Probióticos , Animales , Traslocación Bacteriana , Colesterol/sangre , Grasas de la Dieta/administración & dosificación , Hipercolesterolemia/etiología , Lactobacillus/crecimiento & desarrollo , Lactobacillus/fisiología , Lipoproteínas HDL/sangre , Lipoproteínas LDL/sangre , Hígado/microbiología , Ratones , Bazo/microbiología , Triglicéridos/sangreRESUMEN
The effect of bile on beta-galactosidase activity and cell viability was investigated using two strains of Lactobacillus reuteri that were subjected to freeze-drying. In the presence of 0.15% oxgall, beta-galactosidase activity of the whole cells was significantly increased. After lyophilization, the cultures that had been treated with oxgall showed a low survival rate without changes in beta-galactosidase activity. The poor resistance of the cells to damage from freeze-drying might be related to the presence of membranous structures containing simple folds and buds of the cell membrane, as was observed by transmission electron microscopy.