The genomic DNA used to determine the DNA G+C
contents of the novel and reference strains and to
investigate DNA–DNA relatedness values among the same
strains was extracted according to the method of Marmur
(1961). To assess its G+C content, DNA was enzymically
degraded into nucleosides (Mesbah et al., 1989) and then
separated by HPLC. The genomic DNA G+C contents of
the four novel strains (50.9–51.7 mol%) were very similar
to the corresponding values for the type strains of the four
recognized subspecies of L. delbrueckii (50.5–54.3 mol%).