摘要
为了研究食品、化妆品菌落总数测定中使用三苯甲基四氮唑(TTC)对细菌生长的影响和使用TTC的最适合浓度,本文分别用大肠埃希菌、创伤弧菌、铜绿假单胞菌、金黄色葡萄球菌、蜡样芽胞杆菌经纯化培养后调成n×108CFU/mL浓度作为测验用菌液,分别配制含0.1‰、0.2‰、0.3‰、0.4‰、0.5‰的TTC的平板计数琼脂,同时以不添加TTC的平板计数琼脂作为对照,观察菌落生长情况及进行菌落总数计数。结果显示,大肠埃希菌在0.1‰~0.5‰浓度TTC时均生长良好,测试组和对照组差异无统计学意义(P>0.05);创伤弧菌、铜绿假单胞在0.4‰TTC时生长良好,测试组和对照组差异无统计学意义(P>0.05);金黄色葡萄球菌、蜡样芽胞杆菌0.2‰TTC时生长良好,测试组和对照组差异无统计学意义(P>0.05),当添加TTC浓度为0.3‰时,革兰氏阳性菌的生长有较为明显的抑制作用,添加0.4‰菌落不能生长。鉴于以上试验结果,在进行食品、化妆品菌落总数测定时,建议使用浓度为0.1‰~0.2‰TTC平板计数琼脂,这样既能区分菌落与起样品残渣颗粒又不会抑制菌落生长,能提高菌落计数准确性。
In order to searching the most suitable concentration of TTC in plate count agar(PCA), the effect of TTC is investigated by the examination of bacteria aerobic count in food and cosmetics. Methods: The bacterial suspensions are prepared to n×108 CFU/mL with purified cultured bacteria, E.coli, V.alginolyticus,P.aeruginosa, S.aureus and B.cereus were used respectively. In the assays, the concentration of TTC added in PCA are 0.1‰, 0.2‰, 0.3‰, 0.4‰, 0.5‰ respectively, take TTC free PCA as control. After cultivation, we observed the situation of colony growth and count the total number of colonies. The results show that the E.coli grew well in plate count agar with TTC at any concentrations(P>0.05). V.alginolyticus and P.aeruginosa, grew well in PCA with TTC at concentration of 0.4‰(P>0.05), and there is no significant difference with the control group.S.aureus and B.cereus grew well in PCA with TTC at concentration of 0.2‰(P>0.05), and there is no significant difference with the control group.When the TTC concentration is 0.3‰, it could inhibit the growth of Gram-positive bacteria, and at the concentration of 0.4‰ TTC, Gram-positive bacteria colonies could not grew in. In view of the above assay results, it is recommended that the concentration of 0.1‰ -0.2‰ TTC in PCA could can play an effective indicator role in distinguish colonies from sample residue particles without inhibiting colony growth,which could improve the accuracy of colony counting when measuring the total number of colonies in food and cosmetics.
作者
王曦
李志勇
李婉华
WANG Xi;LI Zhiyong;LI Wanhua(Guangdong Institute of Food Inspection(Guangdong Inspection Center of Wine and Spirits,Guangzhou,Guangdong,510435,China;Guangzhou Customs District Technology Center;Guangzhou land bridge Testing Technology Co.Ltd.)
出处
《检验检疫学刊》
2019年第6期36-38,46,共4页
Journal of Inspection and Quarantine
