Bacteria

Patent metadata

Field	Value
Publication number	US-11272716-B2
Application number	US-201716329727-A
Country	US
Kind code	B2
Filing date	Aug 24, 2017
Priority date	Sep 1, 2016
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

The present invention relates to a bacterial cell with texturizing property, starter cultures comprising the cell, and dairy products manufactured using the bacterial cell.

First claim

The invention claimed is:

1. A method for increasing viscosity in a fermented milk product, comprising inoculating and fermenting a milk substrate with a mutant lactic acid bacterium (LAB) exhibiting one or more properties selected from:
(a) containing from 0 to less than 10 parts per million (ppm, mg/kg dry weight) of Fe 2+ ions;
(b) containing from 0 to less than 6 ppm of Mn 2+ ions;
(c) containing from 0 to less than 16 ppm in total of Fe 2+ ions and Mn 2+ ions;
(d) carrying a mutation in a gene related to the uptake of a divalent metal ion;
(e) having a changed fur gene expression caused by one or more of: a mutation that causes partial or full inactivation of the fur gene, a mutation that causes partial or full deletion of the fur gene, and a mutation that causes insertion of DNA into the fur gene;
(f) having reduced mnth gene expression caused by one or more of: a mutation that causes partial or full inactivation of the mnth gene, a mutation that causes partial or full deletion of the mnth gene, and a mutation that causes insertion of DNA into the mnth gene;
(g) having reduced fatc gene expression caused by one or more of: a mutation that causes partial or full inactivation of the fatc gene, a mutation that causes partial or full deletion of the fatc gene, and a mutation that causes insertion of DNA into the fatc gene; and
(h) being resistant to tellurite, as determined by an ability to form a colony on M17 agar plates containing 0.1 mM K 2 TeO 3 ,
wherein the mutant LAB generates a viscosity in milk greater than about 50 Pa·s, measured as shear stress, after inoculating 9.5% reconstituted skim milk with 10 8 CFU/ml milk of the mutant LAB and fermenting for 16 hours at 37° C.

2. The method of claim 1 , wherein the mutant LAB exhibits one or more properties selected from:
(a) containing from 0 to less than 10 parts per million (ppm, mg/kg dry weight) of Fe 2+ ions;
(b) containing from 0 to less than 6 ppm of Mn 2+ ions; and
(c) containing from 0 to less than 16 ppm in total of Fe 2+ ions and Mn 2+ ions.

3. The method of claim 1 , wherein the mutant LAB exhibits one or more properties selected from:
(d) carrying a mutation in a gene related to the uptake of a divalent metal ion;
(e) having a changed fur gene expression caused by one or more of: a mutation that causes partial or full inactivation of the fur gene, a mutation that causes partial or full deletion of the fur gene, and a mutation that causes insertion of DNA into the fur gene;
(f) having reduced mnth gene expression caused by one or more of: a mutation that causes partial or full inactivation of the mnth gene, a mutation that causes partial or full deletion of the mnth gene, and a mutation that causes insertion of DNA into the mnth gene;
(g) having reduced fatc gene expression caused by one or more of: a mutation that causes partial or full inactivation of the fatc gene, a mutation that causes partial or full deletion of the fatc gene, and a mutation that causes insertion of DNA into the fatc gene; and
(h) being resistant to tellurite, as determined by an ability to form a colony on M17 agar plates containing 0.1 mM K 2 TeO 3 .

4. The method of claim 1 , wherein the mutant LAB has a perturbed divalent metal ion metabolism (DMIM) as compared to its mother strain.

5. The method of claim 4 , wherein the divalent metal ion is selected from one or more of Fe 2+ , Mg 2+ , and Mn 2+ .

6. The method of claim 1 , wherein the mutant LAB has been obtained by mutagenesis.

7. The method of claim 1 , wherein the mutant LAB has been obtained by genetic engineering.

8. The method of claim 1 , wherein the mutant LAB has been obtained by a process comprising growth in a medium having a concentration of one or both of Fe 2+ and Mn 2+ of from 0 to below 0.25 μg/g.

9. The method of claim 1 , wherein the mutant LAB belong to the species Lactobacillus bulgaricus.

10. The method of claim 1 , wherein the mutant LAB belong to the species Streptococcus thermophilus.

11. The method claim 1 , wherein the mutant LAB is selected from Streptococcus thermophilus strain CHCC15712 deposited at Deutsche Sammlung von Mikroorganismen and Zellkulturen GmbH, Braunschweig, Germany, under accession number DSM25955, and mutants thereof wherein less than 0.1% of the nucleotides in the bacterial genome of the mutant have been changed relative to CHCC15712 and wherein the mutant exhibits the same or improved properties with respect to exopolysaccharide (EPS) production as CHCC15712.

12. The method of claim 1 , wherein the mutant LAB is provided in a composition comprising a metal ion chelator.

13. The method of claim 1 , wherein the milk substrate has a concentration of one or both of Fe 2+ and Mn 2+ of from 0 to below 0.25 μg/g.

14. The method of claim 1 , wherein the milk substrate comprises Fe 2+ ions and the method further comprises removing Fe 2+ ions from the milk substrate before, during or after inoculation with the mutant LAB, to obtain a milk substrate having a Fe 2+ concentration from 0 to below 0.25 μg/g.

15. The method of claim 1 , wherein the milk substrate comprises Mn 2+ ions and the method further comprises removing Mn 2+ ions from the milk substrate before, during or after inoculation with the mutant LAB, to obtain a milk substrate having a Mn 2+ concentration from 0 to below 0.25 μg/g.

Assignees

• Chr Hansen As

Inventors

• Derkx Patrick
• Janzen Thomas
• Soerensen Kim Ib

Classifications

• C12N1/20 Primary

  Bacteria; Culture media therefor · CPC title

• A23C9/1238

  using specific L. bulgaricus or S. thermophilus microorganisms; using entrapped or encapsulated yoghurt bacteria; Physical or chemical treatment of L. bulgaricus or S. thermophilus cultures; Fermentation only with L. bulgaricus or only with S. thermophilus · CPC title

• A23C19/0323 Primary

  using only lactic acid bacteria, e.g. Pediococcus and Leuconostoc species; Bifidobacteria; Microbial starters in general (using moulds A23C19/0682) · CPC title

• C12R2001/46

  Streptococcus {; Enterococcus; Lactococcus} · CPC title

• C12N1/205

  Bacterial isolates · CPC title