The acidic exopolysaccharide (EPS) secreted in large amounts by the symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum bv. trifolii is required for the establishment of an effective symbiosis with the host plant Trifolium spp. EPS biosynthesis in rhizobia is a very complex process regulated at both transcriptional and post-transcriptional levels and influenced by various nutritional an...

Rhizobium leguminosarum bv. trifolii pssA encodes a glucosyl-isoprenylphosphate (IP)-transferase involved in the first step of exopolysaccharide (EPS) synthesis. It was found that the pssA gene is an important target for regulation of this biosynthetic pathway. The data of this study indicate that pssA transcription is a very complex and mainly positively regulated process. A detailed analysis ...

The involvement of Rhizobium enzymes that degrade plant cell wall polymers has long been an unresolved question about the infection process in root nodule symbiosis. Here we report the production of enzymes from Rhizobium leguminosarum bv. trifolii that degrade carboxymethyl cellulose and polypectate model substrates with sensitive methods that reliably detect the enzyme activities: a double-la...

In a previous report, synthetic and natural biotin were stated to have identical growth-promoting properties for Lactobacillus arabinosus 17-5 (1). This paper gives a more detailed comparison of these substances in the growth of four other biotin-requiring microorganisms. The activities of synthetic dland I-biotin, dl-allobiotin, dl-diamino acid sulfate, desthiobiotin,’ and the probable biologi...

An investigation was carried out to determine the genetic structure in soil populations of Rhizobium leguminosarum bv. trifolii and viciae at each of two Oregon sites (A and C) that were 1 km apart. Although the soils were similar, the plant communities were quite different because grazing by domestic animals had been allowed (site A) or prevented (site C). Analysis of allelic variation at 13 e...

Se evaluó la biodegradación de polietilenglicol peso molecular 400 - PEG con el consorcio Pseudomonas sp. y Rhizobium trifolii en reactores Batch; para determinar las condiciones óptimas operación del reactor se preparó medio sales mínimas esenciales suplementado peptonaCSMEP; estos medios estimó comportamiento temperatura entre 15-37°C, pH un rango 5-9 concentración .1-2%. Con los resultados o...