DNA–DNA hybridizations were performed in microdilution
wells; photobiotin was used for the DNA labelling
(Ezaki et al., 1989). Reciprocal hybridization experiments
were carried out at 45 uC for 2 h in the presence of 50 %
(v/v) formamide, using biotinylated DNA and unlabelled,
single-strand DNA that had been bonded, non-covalently,
to microplate wells. For each hybridization, the highest
and lowest values from eight replicate wells were excluded
before the means of the six remaining values were
calculated and recorded as a relatedness value. The DNA–
DNA relatedness values among the four novel strains
were high (at least 94.8 %), whereas those between
strain YIT 11221T and L. delbrueckii subsp. bulgaricus YIT
0181T (91.6 %), L. delbrueckii subsp. delbrueckii YIT 0080T
(88.7 %), L. delbrueckii subsp. indicus YIT 11751T (90.1 %)
and L. delbrueckii subsp. lactis YIT 0086T (89.0 %) were
slightly lower. These values indicate that the four novel
strains belong to a single taxon within the species L.
delbrueckii (Table S2).