Physiological Characteristics and Production of Vitamin K2 by Lactobacillus fermentum LC272 Isolated from Raw Milk

In order to develop a new starter culture for fermented milk, Lactobacillus fermentum LC272 was isolated from raw milk and its physiological characteristics were investigated. The vitamin K2 concentration of L. fermentum LC272 was 184.94 μg/L in Rogosa medium and 63.93 μg/L in the reconstituted skim milk. The optimum growth temperature for L. fermentum LC272 was determined to be 40℃ and it took 24 h for the pH to reach 5.2 under this condition. L. fermentum LC272 was more sensitive to rifampicin relative of the other 15 different antibiotics tested, and showed most resistance to streptomycin. L. fermentum LC272 showed higher activities to leucine arylamidase and acid phosphatase. It was comparatively tolerant to bile juice and acid and displayed high resistance against Salmonella Typhimurium and Staphylococcus aureus with rates of 82.9 and 86.3% respectively. These results demonstrated that L. fermentum LC272 could be an excellent starter culture for fermented milk with high levels of vitamin K2 production.