Curdlan was produced in high yield by cultures of a newly isolated and improved mutant strain of Alcaligenes faecalis var. myxogenes. Curdlan forms a gel with specific properties and it should be a useful, new polymer not only as a food additive, but also for industrial purposes.
I. FindingsThe history of the discovery of curdlan is interesting. In 1962, Harada and his colleagues made great efforts to obtain microorganisms which could utilize petrochemical materials. They isolated an organism from soil, capable of growing on medium containing 10% ethylene-glycol as the sole carbon source (1) and named it Alcaligenes faecalis var. myxogenes 10C3 (2, 3). They found that this organism produced a new β-glucan which contained about 10% succinic acid and named it succinoglucan (4, 5) . The structure of the polysaccharide moiety of succinoglucan (6, 7) is shown below:-->Glcl-->4Glcl-->3Glcl-->3Glcl-->6Glcl-->4Glcl-->3Glcl-->3Glcl-->4Glcl-->3Gall-->4Glcl--> During investigations on the production of succinoglucan, one day they found that the culture medium did not become viscous and no succinoglucan was formed, but almost all the added glucose was consumed. They thought that some special compound(s), must have been produced instead of succinoglucan in the culture. So they examined the product and found that it was a neutral polysaccharide (8, 9). They named it curdlan in 1966 (10).Curdlan is composed of β-l,3-glucosidic linkages. A mutant strain 10C3K was isolated from the stock culture 10C3, which produced only curdlan. Strain 10C3K is a spontaneous mutant and it has stable ability to produce the exocellular polysaccharide whereas the ability of strain 10C3 is unstable(11). Thus, by chance, they succeeded in obtaining a suitable organism for pro duction of curdlan. Later Takeda Chemical Industries Ltd.isolated 265