Cyclic 3-1 - 2 Glucans Cyclosophorans

The cyclosophorans are secreted into the culture medium but are also found associated with the cell [31]. Cellular concentrations range between 5 and 20% of the total dry cell weight. They are located primarily in the periplasmic space. Their secretion from the cell varies greatly for the different species and is influenced by the stage of growth and conditions of growth such as the composition of the medium and the temperature [39,40]. Large amounts of extracellular cyclosophorans are found after the stationary phase of the culture has been reached [39-41]. 

The cyclosophorans are sometimes substituted with anionic substituents such as 1-phosphoglycerol, succinic acid, and methyl malonic acid [42-46] 1-phos- 

Several species of Bradyrhizobium synthesize cyclic dextrins that have both P-1- 6 and P-1 3-linked D-glucose residues [52-54]. These cyclodextrins are similar to the cyclic P-1 — 2 D-glucose dextrins elaborated by A. tumefaciens and 

D-glucan apparently has similar roles for the bacteria, as do the cyclosophorans. 

A cyclodextrin containing only P-1 3-linked D-glucose residues (a cyclo-laminarinose) has been found to be elaborated by a recombinant strain of Rhizo-bium meliloti TY7, a cyclic P-1 2 D-glucan-deficient mutant that carries a genetic locus for the cyclo P-1 — 6/p-l 3 D-glucan elaborated by B. japonicum 

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Cyclosophorans Agrobacterium sp., Rhizobium sp., Xanthomonas sp. Cyclic (1 — 2)- 8-D-glucans... 

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