Method for culturing lactic acid bacterium and method for producing fermented milk

A method comprising:

• a culture solution preparation step of preparing a culture solution containing whey degraded by a proteolytic enzyme;
• a culture step of
• inoculating bacteriocin-producing, lactic acid bacteria, which belongs to Lactobacillus gasseri, into said culture solution,
• culturing said bacteriocin-producing, lactic acid bacteria until a pH of said culture solution inoculated with said bacteriocin-producing, lactic acid bacteria becomes lower than 5,
• after the pH becomes lower than 5, culturing said bacteriocin-producing, lactic acid bacteria while maintaining the pH of said culture solution inoculated with said bacteriocin-producing, lactic acid bacteria to be lower than 5 and not lower than 4.7 by adding an alkaline solution to said culture solution inoculated with said bacteriocin-producing, lactic acid bacteria;
• an add step of adding into a yogurt mix, a culture of said bacteriocin-producing, lactic acid bacteria produced by said culture step, and a starter, wherein the yogurt mix is a raw material milk for forming fermented milk;
• and
• a ferment step of fermenting said yogurt mix which includes the culture of said bacteriocin-producing, lactic acid bacteria and the starter,
• wherein the culture of said bacteriocin-producing, lactic acid bacteria is produced by said culture step which is done separately from said ferment step.