基于PI荧光图像计数的乳制品荧光性质分析

Analysis of the Fluorescence Properties of Dairy Products Based on Propidium Iodide Fluorescence Image Counting

摘要:

为分析添加PI染料时乳制品中不同的荧光成分如酪蛋白、黄油、维生素B1、维生素B2、维生素C等对荧光图像观察的影响，探究了不同乳制品及其成分在PI染色观察条件下的荧光性质，并以酿酒酵母为目标菌，研究了10种乳制品中酿酒酵母PI荧光图像计数结果。结果表明，酪蛋白、黄油、维生素B1、维生素B2、维生素C等成分及10种乳制品在发射光615 nm均可产生荧光，但不影响PI染色的酿酒酵母荧光计数的观察结果。使用荧光显微镜对添加105~107 CFU/mL酿酒酵母菌液的10种乳制品进行PI染色计数，并将荧光图像计数结果与平板计数结果进行比较。其中经荧光图像计数后得到的菌液浓度对数值分别在5.69~5.93、6.18~6.28、7.13~7.21之间，对应平板计数结果的对数值分别5.49~5.63、6.02~6.06、7.02~7.06之间，二者结果一致。使用 PI 进行荧光图像计数时，乳制品荧光虽然存在但不会对酿酒酵母荧光图像观察与计数造成影响。

Abstract:

The fluorescence properties of various components, such as casein, butter, vitamin B1, vitamin B2, and vitamin C, in dairy products treated with propidium iodide (PI) dye were examined to assess their effects. Saccharomyces cerevisiae was selected as the target bacterium to investigate bacterial counts using PI fluorescence images in ten dairy products. The findings demonstrated that casein; butter; vitamins B1, B2, and C; and ten other types of dairy products produced fluorescence at an emission wavelength of 615 nm, but they had no effect on fluorescence in S. cerevisiae treated with PI. Bacterial counts were determined in ten dairy products inoculated with 105~107 CFU/mL of S. cerevisiae using PI staining and fluorescence microscopy. The bacterial count results obtained from fluorescence imaging and plate counting were compared. Based on fluorescent image counting, the logarithmic values of the bacterial concentration were 5.69~5.93, 6.18~6.28, and 7.13~7.21, respectively, whereas the logarithmic values of plate counting were 5.49~5.63, 6.02~6.06, and 7.02~7.06, respectively. The results of the two methods were consistent. Thus, although dairy products and their components emit fluorescence, it does not affect the observation or bacterial counting in fluorescence images when PI is used.