Extracellular polysaccharide production by a <i>Rhizobium</i> sp. isolated from legume herb <i>Crotalaria</i> <i>saltiana </i>Andr.

Abstract

A symbiont, isolated from root nodules of <i>Crotalaria saltiana</i> Andr., was identified as <i>Rhizobium</i> sp. It<i> </i>produced large amount of extracellular polysaccharides (EPS) in broth culture in yeast extract mannitol (YEM) medium. The EPS production and growth started simultaneously, though they have different stationary phases. The symbiont produced maximum EPS (16 <img src='/image/spc_char/micro.gif' border=0>g/mL) when the medium was supplemented with preferable carbon (glucose) 2%, nitrogen (glycine) 0.1%, and vitamin (biotin) 1 <img src='/image/spc_char/micro.gif' border=0>g/mL. Attempts were made to optimize the cultural requirements for growth and EPS production. The EPS produced by the symbiont contained glucose and galactose. The possible role on <i>Rhizobium</i> root nodule symboiosis has been discussed in the light of EPS production.