Non-CRISPR-mediated phage resistant Streptococcus thermophilus
AssigneeDsm IP Assets B.V.
InventorsRoelof Hendrik Matthijs Kouwen, Laurens Leendert Hanemaaijer, Douwe Van Sinderen, Brian McDonnell, Jennifer Mahony
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Abstract
The present invention provides a method for the construction of a bacteriophage-insensitive mutant of a Streptococcus thermophilus parent strain whereby the bacteriophage insensitivity is not based on the CRISPR resistance mechanism but based on another mechanism. The method provides a protocol by which this can be achieved by inactivating one or more of the CRISPR systems present in a given strain. The invention also provides the bacteriophage-insensitive mutants as well as their use in a process for making a dairy product.
Claims11
A method for the isolation of bacteriophage-insensitive mutants from a Streptococcus thermophilus parent strain comprising:
- a. inactivating the CRISPR resistance mechanism of the parent strain;
- b. exposing the parent strain obtained in step a. to a bacteriophage to obtain bacteriophage insensitive mutants;
- c. isolating the bacteriophage insensitive mutants;
- d. comparing the CRISPR loci of the parent strain with the CRISPR loci of the bacteriophage insensitive mutants;
- and
- e. selecting bacteriophage-insensitive mutants of which the CRISPR loci is identical to the CRISPR loci of the parent strain.
A bacteriophage-insensitive mutant of a Streptococcus thermophilus parent strain wherein the CRISPR loci of the bacteriophage-insensitive mutant are not identical to the CRISPR loci of the parent Streptococcus thermophilus strain, wherein the bacteriophage-insensitive mutant further comprises a non-CRISPR-mediated bacteriophage resistance, and wherein said Streptococcus thermophilus parent strain is a strain which was deposited as CBS138555 or CBS139996.
Dependencies are inferred from the claim text.