The Escherichia coli lacZ reversion mutagenicity assay

The Escherichia coli lacZ reversion assay, based on the set of episomal lac Z alleles engineered by Miller et al., provides an attractive system for st udies of mutagenesis and mutational specificity. Each strain in the lacZ se t reverts by a specific base substitution or frameshift event. Revertants a re selected by growth on lactose minimal medium. In this review, I describe the development of the assay and its subsequent modifications and improvem ents. Examples of its application are presented and detailed protocols for the implementation of the assay are given. (C) 2000 Elsevier Science B.V. A ll rights reserved.