TABLE 1.

Transformation frequencies of the 13 laboratory pneumococcal strains

Identification	Serotype	Transformants/∼108 pneumococci (mean ± SEM)	RTFa	Transformability	Reference(s)
R6	NTb	3.92 × 106 ± 0.61 × 106	1.00 ± 0.16	High	82
Rx1	NT	4.67 × 107 ± 0.21 × 107	11.91 ± 0.54	High	83, 84
ST556	19F	1.48 × 104 ± 0.23 × 104	0.003759 ± 0.000600	Intermediate	12, 85
Taiwan19F-14 (ATCC 700905)	19F	1.14 × 104 ± 0.14 × 104	0.003104 ± 0.000371	Intermediate	86
G54	19F	1.61 × 104 ± 0.19 × 104	0.004099 ± 0.000496	Intermediate	87
D39 (NCTC 7466)	2	3.63 × 103 ± 0.59 × 103	0.000925 ± 0.000151	Low	88
TIGR4 (ATCC BAA334)	4	1.39 × 103 ± 0.13 × 103	0.000353 ± 0.000034	Low	89
P376 opaque variant	6A	1.33 × 102 ± 0.75 × 102	0.000036 ± 0.000019	Low	90
P384 transparent variant	6A	1.21 × 103 ± 0.14 × 103	0.000330 ± 0.000004	Low	90
P763 opaque variant	6B	6.44 × 102 ± 1.24 × 102	0.000176 ± 0.000032	Low	91
P765 transparent variant	6B	2.69 × 103 ± 0.38 × 103	0.000734 ± 0.000097	Low	91
EF3030	19F	2.54 × 103 ± 0.24 × 103	0.000694 ± 0.000062	Low	92
A66.1	3	2.61 × 102 ± 1.58 × 102	0.000071 ± 0.000041	Low	83, 84

^aRTF, relative transformation frequency.

^bNT, nontypeable.