Method for transforming a bacterium belonging to the

1. An isolated peptide comprising at least 7 amino acids and at most 24 amino acids, wherein the isolated peptide has an amino acid sequence as set forth in SEQ ID NO: 3 when the isolated peptide is 24 amino acids long and the isolated peptide comprises a portion of SEQ ID NO: 3 including at least PYFTGCL (SEQ ID NO: 128) when the isolated peptide includes 23 amino acids or less, and wherein said peptide induces or increases competence in a S. thermophilus strain.

2. The isolated peptide according to claim 1 , wherein said peptide induces or increases competence in the S. thermophilus strain LMD-9 in which the endogenous gene encoding SEQ ID NO:1 has been inactivated.

3. The isolated peptide according to claim 1 , wherein said peptide contains at most 23 amino acids, at most 22 amino acids, at most 21 amino acids, at most 20 amino acids, at most 19, at most 18, at most 17, at most 16, at most 15, at most 14, at most 13, at most 12, at most 11, at most 10, at most 9, or at most 8.

4. The isolated peptide according to claim 1 , wherein the C-terminal end of said isolated peptide has an amino acid sequence of TGCL (SEQ ID NO: 131).

5. The isolated peptide according to claim 1 , wherein said isolated peptide is selected from the group consisting of:

(SEQ ID NO: 112)

KKLKLFTLFSLLITILPYFTGCL,

(SEQ ID NO: 113)

KLKLFTLFSLLITILPYFTGCL,

(SEQ ID NO: 114)

LKLFTLFSLLITILPYFTGCL,

(SEQ ID NO: 115)

KLFTLFSLLITILPYFTGCL,

(SEQ ID NO: 116)

LFTLFSLLITILPYFTGCL,

(SEQ ID NO: 117)

FTLFSLLITILPYFTGCL,

(SEQ ID NO: 118)

TLFSLLITILPYFTGCL,

(SEQ ID NO: 119)

LFSLLITILPYFTGCL,

(SEQ ID NO: 120)

FSLLITILPYFTGCL,

(SEQ ID NO: 121)

SLLITILPYFTGCL,

(SEQ ID NO: 122)

LLITILPYFTGCL,

(SEQ ID NO: 123)

LITILPYFTGCL,

(SEQ ID NO: 124)

ITILPYFTGCL,

(SEQ ID NO: 125)

TILPYFTGCL,

(SEQ ID NO: 126)

ILPYFTGCL,

(SEQ ID NO: 127)

LPYFTGCL,

and

(SEQ ID NO: 128)

PYFTGCL.

6. The isolated peptide according to claim 1 , wherein said isolated peptide is or comprises the amino acid sequence PYFTGCL (SEQ ID NO: 128).

7. The isolated peptide according to claim 1 , wherein the peptide is synthetic.

8. A method for inducing and/or increasing competence in a bacterium belonging to the Streptococcus genus comprising incubating the bacterium in a medium comprising an isolated peptide according to claim 1 and/or a bacterium producing an isolated peptide according to claim 1 .

9. A kit-of-parts comprising:

a bacterium belonging to the Streptococcus genus in a first part; and

in a second part, an isolated peptide according to claim 1 and/or a bacterium producing an isolated peptide according to claim 1 .