Salinity-induced accumulation of poly-β-hydroxybutyrate in rhizobia indicating its role in cell protection

Poly beta -hydroxybutyrate (PHB) is an energy and carbon storage material accumulated in response to the limitation of an essential nutrient. The effect of different salt concentrations on growth and PHB accumulation of four different Sinorhizobium strains was examined. Irrespective of the strain, a defined trend in the accumulation of PHB inside the cells was observed. While minimum PHB content was accumulated at low or zero salinity, maximum was observed by the salt-tolerant strains at higher salt concentrations. This suggests a definite role for PHB in cell protection in saline conditions.