High Production of Polysialic Acid [Neu5Acα(2-8)-Neu5Acα(2-9)]nbyEscherichia coliK92 Grown in a Chemically Defined Medium. Regulation by Temperature

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Abstract
The capsular polysaccharide of Escherichia coli K92 consists of a linear polymer of Neu5Ac with alternating .alpha.(2-8) and .alpha.(2-9) linkages. It accumulates when the bacterium is grown at 37.degree. C in a defined medium containing D-xylose and L-asparagine as carbon and nitrogen sources. Release of the capsular polymer into the medium was maximal (450 .mu.g .times. ml-1) in the stationary phase of growth (76 h). This medium could be useful for obtaining sufficient polymer to develop effective vaccines. The enzyme, CMP-Neu5Ac synthetase, was not detected in cells grown at 20.degree. C. The lack of this enzyme explains the absence of polymer biosynthesis when the bacterium was grown at 20.degree. C.