Development Of Chromogenic Medium And Detection Method Of Bifidobacterium

The beneficial function in intestinal Bifidobacterium has been subjected to people's attention, so more and more bifidobacteria are being added to food and health care products, so detecting the existence and content of bifidobacteria in these products is particularly important for the quality assurance and monitoring. At present, the most widely used detection method of Bifidobacterium is still the national standard one. Although this method can accurately count the content, the testing duration is long, and the operation is complicated.This study is aimed to find an accurate and rapid detection method of bididobacteria. Based on LBS agar, some promoters or inhibitors were added in the cultivation medium of bifidobacteria, as well as some chromogenic substrate. Through orthogonal experiment and variance analysis, the optimum formulation of Bifidobacterium chromogenic medium was screened.On the optimum Bifidobacterium chromogenic medium, the Bifidobacterium can grow well with characteristic blue color, while other non-bifidobacteria, such as Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Salmonella sp., Escherichia coli and Staphylococcus aureus, were inhibited or displayed white color, which demonstrated that the medium selected in this study is accurate and effective. Correspondingly, the chromogenic plate counting method of Bifidobacterium was established. Among the Bifidobacterium type strains and other food borne type strains, the specificity and detection limit of this method were evaluated; Among 200 natural samples purchased from the market, the detection cost, time, and accuracy were evaluated. All the evaluation processes used the national standard detection method as reference. Consequently, after 48 h cultivation at 36 oC on the chromogenic medium, the positive samples can easily distinguished with clear blue color and then directly counted, and the detection cost was significantly lower than the national standard test method; the specificity of the chromogenic medium was high, being evaluated by 200 natural samples, with a similar accuracy as the national standard method and there was no significant difference(F=3.7946, P > 0.05). The bifidobacteria chromogenic medium and detection method developed in this study has the advantages of low cost, rapidness, high specificity, good accuracy, which can meet the needs of Bifidobacterium detection in food industry.