Olsson E
Vet Microbiol. 1982 Jul;7(3):253-66. doi: 10.1016/0378-1135(82)90038-4.
Casamino acids-yeast extract medium (CAY) and a tryptone-yeast extract medium (TY-1) were evaluated in testing for production of heat-stable enterotoxin (ST) by porcine strains of Escherichia coli using the infant mouse assay. More strains were ST-positive when grown in CAY medium than in TY-1 medium. Questionably or indeterminately ST positive strains were investigated in detail to determine whether or not they were weak ST producers. Growth in four different media and in different batches of CAY medium, inactivation of culture supernatant fluids at a lower temperature, addition of mitomycin C to growing cultures and preparation of periplasm-cytoplasm fractions of bacteria by sonication, all failed to yield ST positive samples. ST value limits (i.e. ratios of intestinal weight to remaining body weight of challenged mice), which clearly differentiated positive or negative strains for ST production, were set for CAY medium. A minimal salts-amino acids medium (MSA) was devised. Both in shake flask and fermenter cultures MSA medium gave better ST yields than CAY and a previously described defined medium.
使用幼鼠试验，对酪蛋白氨基酸 - 酵母提取物培养基（CAY）和胰蛋白胨 - 酵母提取物培养基（TY - 1）进行了评估，以检测猪源大肠杆菌菌株产生热稳定肠毒素（ST）的情况。在CAY培养基中生长的菌株比在TY - 1培养基中生长的菌株更多为ST阳性。对可疑或不确定的ST阳性菌株进行了详细研究，以确定它们是否为弱ST生产者。在四种不同培养基和不同批次的CAY培养基中生长、在较低温度下使培养上清液失活、向生长中的培养物中添加丝裂霉素C以及通过超声处理制备细菌的周质 - 细胞质组分，均未能得到ST阳性样本。为CAY培养基设定了ST值限度（即受攻击小鼠的肠重与剩余体重之比），该限度能清楚地区分ST产生的阳性或阴性菌株。设计了一种最低盐 - 氨基酸培养基（MSA）。在摇瓶培养和发酵罐培养中，MSA培养基产生的ST产量均高于CAY和先前描述的限定培养基。
