lacZ

NEB 5-alpha · DH5α derivative

The published complete genome represents NEB 5-alpha, a named derivative of DH5α.

Do not treat this derivative as an identical reference for every DH5α stock.

Complete Genome Sequence of NEB 5-alpha, a Derivative of E. coli K-12 DH5α

An alpha-complementable lacZ allele

The genome paper reports ΔlacZ58(M15) in a φ80-derived insertion, while the ordinary chromosomal lac region is deleted. The allele supports alpha complementation.

This describes the published NEB 5-alpha stock. ZipHelix has not independently mapped the deletion boundaries or established an edit site.

Complete Genome Sequence of NEB 5-alpha, a Derivative of E. coli K-12 DH5α

Observed outcome · Related strain

lacZ deletion did not slow growth on galactose in this comparison

Table 5 reports the same galactose doubling time for the study wild type and its lacZ-deletion derivative. A lacY amber mutant grew more slowly.

Study strain: MG1655-derived NCM3387 compared with NCM3384

Conditions: Defined medium with galactose and IPTG; this is not a lactose-only growth result.

Physiological Studies of Escherichia coli Strain MG1655: Growth Defects and Apparent Cross-Regulation of Gene Expression

Gene function · Related strain

Lactose breakdown

lacZ encodes beta-galactosidase. Its enzyme activity supports lactose breakdown and chromogenic beta-galactosidase assays.

Study strain: K-12 MG1655

Conditions: A color assay requires a suitable substrate; expression and substrate access also matter.

NCBI Gene: lacZ (b0344)