Huber R E, Hurlburt K L
Can J Microbiol. 1984 Mar;30(3):411-5. doi: 10.1139/m84-060.
Growth on lactose was found to be restricted in an Escherichia coli strain deficient in its ability to transport glucose and galactose. If the latter sugars were removed from the medium as they were being produced, a wild-type strain grew only poorly, while the transport-deficient strain did not grow at all. These results suggested that all of the products of beta-galactosidase action on lactose are released into the medium before being metabolized. This contention was strongly supported by the finding that the appearance of products in the medium was equal to lactose disappearance at three limiting lactose concentrations and by an experiment which showed that essentially all of the label from added lactose ( [1-14C]glucose) was found in the medium as glucose when chased with unlabelled lactose.
在一种缺乏转运葡萄糖和半乳糖能力的大肠杆菌菌株中，发现其利用乳糖生长受到限制。如果在培养基中产生后将后两种糖移除，野生型菌株生长不良，而缺乏转运能力的菌株根本不生长。这些结果表明，β-半乳糖苷酶作用于乳糖的所有产物在被代谢之前都释放到了培养基中。这一观点得到了有力支持，即在三种乳糖限制浓度下，培养基中产物的出现量与乳糖消失量相等，并且通过一项实验表明，当用未标记的乳糖进行追踪时，添加的乳糖（[1-¹⁴C]葡萄糖）中的几乎所有标记都以葡萄糖的形式出现在培养基中。
