RESUMEN
Objetivo: estudiar el efecto de la inoculación con Ensifer meliloti y Halomonas maura sobre el crecimiento y el valor nutricional y funcional de la leguminosa Medicago sativa L., cultivada bajo condiciones de salinidad. Método: las plantas de M. sativa se cultivaron con una solución de mezcla de sales CaSO4 , MgCl, NaCl and NaHCO3 y se coinocularon con su rizobio específico y la bacteria H. maura. Se determinaron los parámetros fisiológicos de las plantas, así como el contenido en nitrógeno y minerales, y se llevó a cabo un proceso de digestibilidad in vitro. Resultados: la salinidad ejerció un efecto negativo sobre las plantas; sin embargo, la coinoculación de las mismas incrementó su productividad, el contenido en nitrógeno, minerales totales, Ca y Mg. Además, los parámetros fisiológicos de potencial hídrico y concentración de leghemoglobina se incrementaron. Tanto la salinidad como la coinoculación de las plantas aumentaron la capacidad antioxidante de la leguminosa en los dializados y retenidos obtenidos tras someter a la planta a un proceso de digestibilidad in vitro. Conclusión: la coinoculación con E. meliloti y H. maura podría mejorar el cultivo de la alfalfa bajo condiciones específicas de salinidad, aumentando su composición nutricional y funcional, pudiendo considerarse en la formulación de suplementos nutricionales para el consumo humano (AU)
Objective: to study the effect of co-inoculation with Ensifer meliloti and Halomonas maura of the leguminous Medicago sativa L., on growth, nutritional and functional value, grown under salinity conditions. Methods: plants of M. sativa were grown in a solution with a mixture of salts (CaSO4 , MgCl, NaCl and NaHCO3 ) and were co-inoculated with its specific rhizobium and the halophilic moderated bacterium H. maura. Different physiologic parameters were determined, as well as, nitrogen and minerals content. Furthermore, an assay of in vitro digestibility was carried out. Results: salinity had a negative effect on the plants; however, co-inoculation increased yield, nitrogen content, total minerals, Ca and Mg. Moreover, physiologic parameters as water potential and leghemoglobin content in fresh nodules were higher compared to those of plants inoculated only with E. meliloti. Both, salinity and bacterial treatment with E. meliloti and H. maura increased the antioxidant capacity of the legume, in dialyzates and retentates collected after an in vitro digestibility assay. Conclusion: co-inoculation of plants with E. meliloti and H. maura could improve the alfalfa yield under specific salinity conditions, increasing the nutritional and functional value of the plants. M. sativa could be considered in the formulations of nutritional supplements for the human diet (AU)
Asunto(s)
Humanos , Medicago sativa , Preparaciones de Plantas/farmacocinética , Valor Nutritivo , Halomonas , Salinidad , Leghemoglobina/análisis , Suplementos Dietéticos/análisisRESUMEN
The moderately halophilic strain Halomonas maura S-30 produces a high-molecular-mass acidic polymer (4.7 x 10(6) Da) composed of repeating units of mannose, galactose, glucose and glucuronic acid. This exopolysaccharide (EPS), known as mauran, has interesting functional properties that make it suitable for use in many industrial fields. Analysis of the flanking regions of a mini-Tn5 insertion site in an EPS-deficient mutant of H. maura, strain TK71, led to the identification of five ORFs (epsABCDJ), which form part of a gene cluster (eps) with the same structural organization as others involved in the biosynthesis of group 1 capsules and some EPSs. Conserved genetic features were found such as JUMPstart and ops elements, which are characteristically located preceding the gene clusters for bacterial polysaccharides. On the basis of their amino-acid-sequence homologies, their putative hydropathy profiles and the effect of their mutations, it is predicted that EpsA (an exporter-protein homologue belonging to the OMA family) and EpsC (a chain-length-regulator homologue belonging to the PCP family) play a role in the assembly, polymerization and translocation of mauran. The possibility that mauran might be synthesized via a Wzy-like biosynthesis system, just as it is for many other polysaccharides, is also discussed. This hypothesis is supported by the fact that EpsJ is homologous with some members of the PST-exporter-protein family, which seems to function together with each OMA-PCP pair in polysaccharide transport in Gram-negative bacteria, transferring the assembled lipid-linked repeating units from the cytoplasmic membrane to the periplasmic space. Maximum induction of the eps genes is reached during stationary phase in the presence of 5 % (w/v) marine salts.
Asunto(s)
Proteínas Bacterianas/metabolismo , Halomonas/metabolismo , Familia de Multigenes/fisiología , Polisacáridos Bacterianos/biosíntesis , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Regulación Bacteriana de la Expresión Génica , Halomonas/citología , Halomonas/genética , Datos de Secuencia Molecular , Polisacáridos Bacterianos/químicaRESUMEN
Salipiger mucescens gen. nov., sp. nov. is a moderately halophilic, exopolysaccharide-producing, Gram-negative rod isolated from a hypersaline habitat in Murcia in south-eastern Spain. The bacterium is chemoheterotrophic and strictly aerobic (i.e. unable to grow under anaerobic conditions either by fermentation or by nitrate or fumarate respiration). It does not synthesize bacteriochlorophyll a. Catalase and phosphatase are positive. It does not produce acids from carbohydrates. It cannot grow with carbohydrates or amino acids as sole sources of carbon and energy. It grows best at 9-10 % w/v NaCl and requires the presence of Na+ but not Mg2+ or K+, although they do stimulate its growth somewhat when present. Its major fatty-acid component is 18 : 1omega7c (78.0 %). The predominant respiratory lipoquinone found in strain A3T is ubiquinone with ten isoprene units. The G + C content is 64.5 mol%. Phylogenetic analyses strongly indicate that this strain forms a distinct line within a clade containing the genus Roseivivax in the subclass alpha-Proteobacteria. The similarity value with Roseivivax halodurans and Roseivivax halotolerans is 94 %. In the light of the polyphasic evidence gathered in this study it is proposed that the isolate be classified as representing a new genus and species, Salipiger mucescens gen. nov., sp. nov. The proposed type strain is strain A3T (= CECT 5855T = LMG 22090T = DSM 16094T).
Asunto(s)
Polisacáridos Bacterianos/biosíntesis , Rhodobacteraceae/clasificación , Rhodobacteraceae/aislamiento & purificación , Microbiología del Suelo , Aminoácidos/metabolismo , Antibacterianos/farmacología , Bacterioclorofila A/análisis , Composición de Base , Metabolismo de los Hidratos de Carbono , Catalasa/análisis , ADN Bacteriano/química , ADN Bacteriano/aislamiento & purificación , ADN Ribosómico/química , ADN Ribosómico/aislamiento & purificación , Ácidos Grasos/análisis , Genes de ARNr , Magnesio/metabolismo , Microscopía Electrónica de Transmisión , Datos de Secuencia Molecular , Monoéster Fosfórico Hidrolasas/análisis , Filogenia , Potasio/metabolismo , Quinonas/análisis , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Rhodobacteraceae/fisiología , Rhodobacteraceae/ultraestructura , Solución Salina Hipertónica/farmacología , Análisis de Secuencia de ADN , Sodio/metabolismo , EspañaRESUMEN
Se realizó un estudio taxonómico de 123 cepas de la familia vibronaceae aisladas desde bivaldos y peces en las costas de Valparaíso. Todas las cepas fueron caracterizadas con 86 test fenotípicos que se agruparon usando el coeficiente Ssm y el análisis de la unión de UPGMA. Las especies fueron agrupadas en tres fenones con un nivel de similitud del 80 porciento. Estas especies fueron identificadas como aeromonas hydrophila, vibrio sp. y plesiomonas shigelloides