유산균 측정을 위한 형광측정법의 안전성 평가

Abstract

The intrinsic fluorescence method is effective for microbial identification and characterization, but there is a need for such a method for monitoring fermentation-related bacteria in fermented food. This methodology is based on monitoring live bacteria that contain a variety of intracellular biomolecules harboring specific emitting photons following excitation by ultraviolet (UV) radiation that characterize their intrinsic fluorescence; however, UV photons can damage cells. Therefore, a safety assessment of the developed method is required before it is used in the food industry to distinguish and enumerate food-associated bacteria. In this study, six lactic acid bacteria (LAB) strains were exposed to UV for four weeks (total irradiation time: 3,009 min) and their safety, including hemolytic activity, undesirable biochemical characteristics, and antibiotic resistance, was evaluated. Moreover, LAB growth inhibition by a UV treatment was also investigated. The results indicated that the six UV-treated LAB strains did not pose any health risk, as they were not hemolytic, exhibited no undesirable biochemical activity, and no antibiotic resistance. Nevertheless, prolonged UV radiation (3,009 min) caused LAB growth inhibition, and that the effect was different depending on the LAB strain and LAB culture medium. Among the six LAB strains, the growth of two strains cultivated in MRS at -1.5℃ was inhibited by long-term UV radiation. On the other hand, the same treatment with UV radiation did not affect the growth of any of the six strains cultivated in kimchi filtrate. Therefore, the intrinsic fluorescence method can be used safely in the food (kimchi) industry for the identification of LAB strains and monitoring their growth during fermentation.