Scandinavian Ropy Milk — Identification and Characterization of Endogenous Ropy Lactic Streptococci and Their Extracellular Excretion

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Abstract
Four bacterial strains isolated from Swedish ropy edible milk were subjected to tests for differentiating group N streptococci. One of the cultures was a variant of S. lactis, previously named S. lactis longi, and the other 3 were variants of S. cremoris with the suggested name S. cremoris longi. Viscosity of dairy products produced with S. cremoris longi was unstable. At optimum growth temperatures stability depended upon the number of serial transfers and on the length of culture incubation. The viscous material produced by S. cremoris longi was most likely a glycoprotein. It consisted of 47% total protein, 20% methyl pentoses, 9.3% protein-bound hexose-like material and a 2.8% sialic acid. A substantial portion of the molecule remains to be identified.
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