Selective cultivation of ampicillin-resistant Escherichia coli: Isolation of bla-expressing transformants on LB agar containing 50 µg/mL ampicillin.

Plasmid cloning and maintenance: Propagation and stable retention of plasmid vectors in Escherichia coli under beta-lactam selection.

Transformation screening: Recovery and selection of colonies following chemical or electroporation-based transformation.

Single-colony isolation and CFU enumeration: Streaking for clonal isolates and quantifying transformant frequency on selective plates.

Blue-white screening (with X-Gal/IPTG): When supplemented, enables lacZ α-complementation screening on an ampicillin background.

Colony PCR and downstream analysis: Picking colonies as templates for PCR, restriction analysis, and sequencing.

Pre-culture selection for protein expression: Verifying correct plasmid-bearing clones prior to induction in liquid culture.

Library and mutagenesis screening: Selecting variants from combinatorial or site-directed mutagenesis libraries using ampicillin selection.