RESUMEN
Beijerinckia derxii, a free-living nitrogen-fixing bacterium, maintained an increasing nitrogenase specific activity during the stationary growth phase. To verify the destination of the nitrogen fixed during this phase, intra and extracellular nitrogenated contents were analyzed. Organic nitrogen and amino acids were detected in the supernatant of the cultures. An increase in intracellular content of both nitrogen and protein occurred. Cytoplasmic granules indicated the presence of arginine. The ability of a non-diazotrophic bacterium (E. coli) to use B. derxii proteins as a source of nitrogen was observed concomitantly with E. coli growth. There is a suggestion that B. derxii contributes to the environment by both releasing nitrogenated substances and accumulating substances capable of being consumed after its death.
Asunto(s)
Beijerinckiaceae/enzimología , Beijerinckiaceae/crecimiento & desarrollo , Nitrógeno/metabolismo , Nitrogenasa/metabolismo , Recuento de Colonia Microbiana , Medios de Cultivo , Escherichia coli/genética , Escherichia coli/metabolismo , Fijación del Nitrógeno , Proteínas/metabolismoRESUMEN
The interactions between the nitrogen-fixing microorganism "Beijerinckia derxii" with two non-diazotrophic bacteria, either "Escherichia coli" or a faculty sulphur-oxidizing chemolitroph, were studied in mixed cultures. Direct and indirect contact between "B. derxii" and "E. coli" were tested. "B. derxii" increased CFU numbers and/or maintained the viability of the non-diazotrophic bacteria, but neither growth nor nitrogenase activity of the nitrogen-fixing bacterium were affected by either partner