Dual-Antibiotic Selection of Transformants: Isolates Escherichia coli colonies carrying plasmids with ampicillin (bla) and chloramphenicol (cat) resistance markers.

Maintenance of Two-Plasmid Systems: Ensures stable co-maintenance of amp- and cm-resistant plasmids in Escherichia coli co-expression or helper plasmid setups.

Colony Screening and Picking: Enables selection and picking of single colonies post-transformation under dual antibiotic pressure for downstream cloning.

Colony PCR and Insert Verification: Supports rapid screening of dual-resistant colonies to confirm presence and orientation of cloned inserts.

CFU Enumeration Under Dual Selection: Quantifies transformation efficiency and viability of Escherichia coli when both markers are required.

Co-Transformation and Conjugation Selection: Selects co-transformants or transconjugants that have acquired both ampicillin and chloramphenicol resistance.

Plasmid Stability Assays: Assesses retention of dual-marker plasmids in Escherichia coli across passages under selective pressure.

Protein Expression Workflows: Maintains expression strains harboring an ampicillin-selectable expression vector plus a chloramphenicol-selectable helper/regulatory plasmid.

Glycerol Stock Preparation: Generates long-term stocks from verified dual-resistant Escherichia coli colonies.

Contamination and Resistance Control Plates: Serves as a control to confirm dual-resistance phenotype and detect non-resistant contaminants.