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.

Disclosed are a yoghurt for regulating intestinal tract, preparation method therefor, and use thereof, where the yogurt is prepared from raw materials comprising the following parts by weight: 90-97 parts of raw milk, Lactobacillus gasseri of (0.7-5)×10.sup.8 CFU/100 g raw milk, Streptococcus thermophilus of (0.1-9)×10.sup.10 CFU/100 g raw milk, Lactobacillus bulgaricus of (0.1-9)×10.sup.10 CFU/100 g raw milk, Lactobacillus acidophilus of (0.5-7)×10.sup.8 CFU/100 g raw milk, Lactobacillus plantarum of (0.5-7)×10.sup.8 CFU/100 g raw milk, Lactobacillus paracasei of (0.1-9)×10.sup.7 CFU/100 g raw milk, and other probiotics, and prebiotics such as inulin. The yogurt may regulate the balance of intestinal flora and prevent constipation and gestational diabetes in overweight and/or obese pregnant women during the gestation period.

The present invention relates to a Streptococcus thermophilus strain, wherein the strain is galactose-fermenting, wherein the strain carries a mutation in the DNA sequence of the glcK gene encoding a glucokinase protein, wherein the mutation inactivates the glucokinase protein or has a negative effect on expression of the gene, and wherein the strain carries a mutation in the promoter region of the GalK gene encoding a galactokinase protein.

A method of fixating and stabilizing nitric oxide metabolites within fermented natural substance according to an embodiment of the present disclosure includes adding a fermentative strain to nitrogen-containing natural substance and carrying out fermentation. The fermentation efficiency is maximized by optimizing the fermentation conditions so that the productivity of nitric oxide metabolites is significantly improved. Thus, eating a fermented natural substance in which nitric oxide metabolites are fixated and stabilized by the method of the present invention would be helpful for maintaining the homeostasis of human body, in which nitric oxide synthase is either absent or insufficient, based on vasodilation and activation of a neurotransmitter and immune function as medical efficacy of nitric oxide.

The present invention relates to fermented plant-based compositions and methods of making the same.