Method of producing Streptococcus thermophilus mutant strains

Patent metadata

Field	Value
Publication number	US-11564399-B2
Application number	US-201816615904-A
Country	US
Kind code	B2
Filing date	May 31, 2018
Priority date	May 31, 2017
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

The present invention is directed to a method of producing a Streptococcus thermophilus strain comprising the steps of a) Providing a mother strain in the form of Streptococcus thermophilus DSM32502, b) Growing a culture of the mother strain in the presence of a bacteriophage, to which the mother strain is not resistant, to obtain a number of mutant strains, which are resistant to the said bacteriophage, c) Measuring the acidification time of the bacteriophage-resistant mutant strains and the mother strain in a milk base and selecting at least one mutant strain with a reduced acidification time as compared to the mother strain to obtain a fast-acidifying mutant strain.

First claim

The invention claimed is:

1. A mutant Streptococcus thermophilus strain which is a mutant of the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32502, wherein the mutant strain carries a mutation which renders the strain resistant to the bacteriophage CHPC1057 deposited at DSMZ under Accession Number DSM23962, and wherein the mutant strain has an acidification time less than 99% of that of the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32502.

2. A mutant strain according to claim 1 , which carries a mutation which renders the strain resistant to bacteriophage CHPC1008 deposited at DSMZ under Accession Number DSM32517.

3. A mutant strain according to claim 1 , wherein the mutant strain has an acidification time of less than 95% of the acidification time of the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32502.

4. A mutant strain according to claim 1 , wherein the mutant strain has a texturizing capacity of at least 95% of that of the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32502, wherein texturizing capacity of each strain is assessed by fermenting a milk base with the respective strain to obtain a fermented milk product, and assessing shear stress of the fermented milk product at a temperature of 13° C. and shear rate of 300 s −1 .

5. A mutant Streptococcus thermophilus strain selected from the group consisting of the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32503, the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32504, the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32505, the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32506, and the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32507.

6. A method of producing a fermented milk product, comprising fermenting a starter culture comprising the mutant strain of claim 1 .

7. A fermented milk product containing the mutant strain of claim 1 .

8. A mutant strain of Streptococcus thermophilus mother strain CHCC23369 deposited at DSMZ under Accession Number DSM32502, wherein the mutant strain is resistant to bacteriophage CHPC1057 deposited at DSMZ under Accession Number DSM23962, wherein the mutant strain has an increased texturizing capacity as compared to the mother strain, and an acidification time less than 99% that of the Streptococcus thermophilus strain deposited at DSMZ under Accession Number DSM32502.

Assignees

• Chr Hansen As

Inventors

• Trihaas Jeorgos
• Janzen Thomas
• Derkx Patrick

Classifications

• A23C2220/202

  Genetic engineering of microorganisms used in dairy technology · CPC title

• C12N15/01

  Preparation of mutants without inserting foreign genetic material therein; Screening processes therefor · CPC title

• C12N1/205

  Bacterial isolates · CPC title

• A23Y2240/75

  Human Necessities · mapped topic

• A23Y2220/15

  Human Necessities · mapped topic