TTC在菌落总数检测中的应用探讨

Application of TTC in the Detection of Aerobic Plate Count

目的:在检测样品中的菌落总数时,为了区分平板上生长的菌落与样品颗粒,在平板计数琼脂中添加2,3,5-三苯基氯化四氮唑,观察不同浓度的2,3,5-三苯基氯化四氮唑对菌落计数的影响。方法:根据国标《食品安全国家标准食品微生物学检验菌落总数测定》(GB 4789.2—2016),在每100 mL PCA琼脂培养基中分别添加0.05 mL、0.10 mL、0.15 mL、0.20 mL、0.25 mL、0.30 mL、0.35 mL、0.40 mL和0.50 mL 1%的2,3,5-三苯基氯化四氮唑,并同时将不添加2,3,5-三苯基氯化四氮唑溶液的PCA琼脂培养基作为对照,观察菌落生长情况。结果:当100 mL平板计数琼脂中2,3,5-三苯基氯化四氮唑含量在2.0~3.5 mg时,实验中所选取的标准菌株菌落能着色且生长状态良好。结论:培养基中2,3,5-三苯基氯化四氮唑含量过低,细菌不易着色;过高,会抑制细菌生长,影响对样品中菌落结果的判断。

Objective: When detecting the total number of colonies in the sample, in order to distinguish the colonies growing on the plate from the sample particles, add 2,3,5-triphenyltetrazolium chloride to the plate counting agar, observe the different concentrations of 2,3,5-effect of triphenyltetrazolium chloride on colony count. Method: According to the GB 4789.2—2016, each 100 mL of PCA AGAR medium was supplemented with 0.05 mL, 0.10 mL, 0.15 mL, 0.20 mL,0.25 mL, 0.30 mL, 0.35 mL, 0.40 mL and 0.50 mL of 1% 2,3, 5-triphenyl tetrazolium chloride, respectively. At the same time, PCA AGAR medium without 2,3, 5-triphenyltetrazolium chloride solution was used as control to observe the growth of colonies. Result: When the content of 2,3,5-triphenyltetrazolium chloride in 100 mL plate counting agar was 2.0~3.5 mg,the colonies of the standard strains selected in the experiment could be colored and grow well. Conclusion: If the content of 2,3,5-triphenyltetrazolium chloride in the medium is too low, the bacteria are not easy to color;if the content is too high, it will inhibit the growth of bacteria and affect the judgment of the colony results in the sample.