Selection of bla/AmpR plasmid transformants: Isolates colonies of carbenicillin-resistant Escherichia coli after chemical or electroporation transformation using LB (1.0% tryptone, 0.5% yeast extract, 1.0% NaCl, 1.5% agar) with 100 µg/mL carbenicillin.

Colony screening for recombinant clones: Enables blue–white or insert screening when supplemented with X-gal/IPTG, facilitating rapid identification of correct constructs in Escherichia coli.

Plasmid maintenance and propagation: Sustains selection pressure for bla-bearing vectors during streaking, passaging, and miniprep culture setup from single colonies.

Single-colony isolation and CFU enumeration: Supports streaking for isolation and quantitative plating to assess transformation efficiency and viability under carbenicillin selection.

Library and variant screening: Enables high-density colony arrays and replica plating on 100 × 100 mm plates for mutagenesis, cloning, and combinatorial libraries in Escherichia coli.

Pre-screening expression strains: Verifies plasmid retention in strains (e.g., T7-based) prior to induction and small-scale expression testing.

Glycerol stock initiation: Provides selective source colonies for long-term cryostorage of engineered Escherichia coli strains.

Quality control of antibiotic-dependent constructs: Confirms functionality of beta-lactamase selection markers and identifies antibiotic loss or plasmid segregation.