Discerning the roles and relationships of EPS and the stringent response

Lee, W.G., Reeve, W.G., O'Hara, G.W. and Tiwari, R.P. (2009) Discerning the roles and relationships of EPS and the stringent response. In: The 16th International Congress of Nitrogen Fixation, 14 - 19 June, Big Sky, Montana.

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Abstract

Exopolysaccharides (EPS) represent an energy expensive composition of high molecular weight sugar polymers. Many physiological roles have been associated with EPS including pathogenesis, biofilm maturation, stress tolerance and symbiotic performance. Coincidentally, many of these functions are paralleled by the stringent response, a phase defined by a metabolic downshift in response to nutrient-limiting conditions. In many rhizobia, the synthesis of EPS and specific stationary phase regulators are required for the successful symbiosis with their legume host. Considerable research has examined the genetic and physical basis by which EPS is produced to initiate plant root infection, however, the physiological conditions that affect and coordinate these genes is not dearly understood. This work aimed to define the roles of EPS and the relationship to stationary phase in Sinorhizobiurn medicae whilst determining specific nutritional elements that affect the level of EPS synthesis.