SODIUM-CHLORIDE STRESS RESULTS IN INCREASED POLY-BETA-HYDROXYBUTYRATEPRODUCTION IN RHIZOBIUM DDSS-69

Sodium chloride stress resulted in the accumulation of poly-beta-hydro xybutyrate (PHB) in Rhizobium cultures raised in unbalanced growth con ditions. This increase was a result of direct synthesis of PHB and not due to a reduced level of PHB breakdown which was evident from the sp ecific activities of beta-ketothiolase and beta-hydroxybutyrate dehydr ogenase. The accumulated PHB serves as a source of nutrition under car bon stress. Rhizobium DDSS 69 switches to alternate pathways of carboh ydrate and nitrogen metabolism under NaCl stress and the osmoprotectan t betaine reverses the osmotic responses induced by NaCl.