The metabolism and genetics of Streptococcus thermophilus (presently Streptococcus salivarius ssp. thermophilus) have only been investigated recently despite its widespread use in milk fermentation processes. The development of recombinant DNA technology has allowed impressive progress to be made in the knowledge of thermophilic dairy streptococci. In particular, it has permitted a careful analysis of phenotypically altered variants which were derived from a mother strain by plasmid or chromosomal DNA reorganization. While natural phage defense mechanisms of S. thermophilus remain poorly documented, information on the bacteriophages responsible for fermentation failures has accumulated. The lysogenic state of two S. thermophilus strains has also been demonstrated for the first time. Gene transfer techniques for this species have been established and improved to the point that targeted manipulation of their chromosomal determinants is now feasible. Cloning and expression vectors have been constructed, and a few heterologous genes were successfully expressed in S. thermophilus. The first homologous genes, involved in carbohydrate utilization, have been cloned and sequenced, shedding some light on the molecular organization of key metabolic steps.

中文翻译：

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嗜热链球菌的分子遗传学。

尽管嗜热链球菌（目前为唾液链球菌嗜热链球菌）的代谢和遗传学最近才被研究，尽管其在牛奶发酵过程中得到了广泛应用。重组DNA技术的发展使嗜热乳链球菌的知识取得了令人瞩目的进展。特别地，它允许仔细分析通过质粒或染色体DNA重组从母株衍生的表型改变的变体。尽管嗜热链球菌的天然噬菌体防御机制仍然文献记载不足，但有关导致发酵失败的噬菌体的信息已经积累。还首次证明了两个嗜热链球菌菌株的溶原状态。已经建立和改进了该物种的基因转移技术，以至于现在可以对它们的染色体决定簇进行靶向操作。已经构建了克隆和表达载体，并且在嗜热链球菌中成功表达了一些异源基因。涉及碳水化合物利用的第一个同源基因已被克隆和测序，为关键代谢步骤的分子组织提供了一些线索。