The fast milk acidifying phenotype of Streptococcus thermophilus can be acquired by natural transformation of the genomic island encoding the cell-envelope proteinase PrtS

Table 1 Characteristics of S. thermophilus strains used in this work

Strain	Phenotype		Genotype		Transformation rate
	F	T	*prtS*	*strA*	(+ 1mM ComS17-24)[20]
LMG18311	F^-	T⁺	-	Trunc.	1.3 x 10^-1
CNRZ1066	F^-	T⁺	-	Trunc.
LMD-9	F⁺	T^-	+	+	5.4 x 10^-3
DGCC7790	F^-	T⁺	-	+
DGCC7710	F⁺	T⁺	+	+	1.0 x 10^-2
DGCC7853	F⁺	T^-	+	+
DGCC7879	F⁺	T^-	+	+
DGCC715	F⁺	T^-	+	+
DGCC7773	F^-	T⁺	-	Trunc.
DGCC7785	F^-	T⁺	-	Trunc.
DGCC7796	F⁺	T^-	+	+
DGCC7854	F⁺	T^-	+	+
DGCC7891/ND03	F^-	T⁺	-	+	1.4 x 10^-4
DGCC7666	F^-	T^-	-	Trunc.	4.2 x 10^-2
DGCC7694	F^-	T^-	-	+
DGCC7809	F⁺	T^-	+	+
DGCC7909	F^-	T⁺	-	Trunc.
DGCC7984	F⁺	T⁺	+	+
DGCC47	F^-	T⁺	-	Trunc.
DGCC7766	F^-	T^-	-	+
DGCC855	F⁺	NT	+	+
DGCC2057	F⁺	T⁺	+	+
DGCC2058	F^-	T⁺	-	+
DGCC9791	F^-	NT	-	+
DGCC7856	F^-	T^-	-	+
DGCC8014	F⁺	T⁺	+	+

All strains are from Danisco collection, excepted strains LMD-9 (ATCC collection), CNRZ1066 (CNRZ collection), ND03[29] and LMG18311 (LMG collection)
For phenotype, F⁺ and F^- respectively refer to fast and slow acidifying strains when grown in pasteurized milk, T⁺ and T^- respectively refer to the presence and absence of texturing properties when grown in pasteurized milk, and NT for not tested.
For genotype, + indicates that the gene is detected and entire, – indicates that prtS is no detected, Trunc. indicates a truncated version of srtA

ISSN: 1475-2859