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

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 Streptococcus lactis, previously named Streptococcus lactis longi, and the other three were variants of Streptococcus cremoris with the suggested name Streptococcus cremoris longi.Viscosity of dairy products produced with Streptococcus 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 Streptococcus 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.