Tri-antibiotic plasmid selection in E. coli: Enrichment of cells harboring plasmids with gentamicin (7 µg/mL), kanamycin (50 µg/mL), and tetracycline (10 µg/mL) resistance markers.

Co-maintenance of multi-plasmid expression systems: Stable culture of strains carrying two or three compatible plasmids with gentamicin-, kanamycin-, and tetracycline-resistance for protein expression and pathway engineering.

Library construction and screening: Selection of combinatorial or CRISPR libraries requiring simultaneous maintenance of multiple antibiotic markers in E. coli.

Overnight growth for plasmid prep: Culturing tri-resistant clones for high-quality mini/midi/maxi preps without marker loss.

Co-transformation recovery and enrichment: Post-transformation outgrowth and selection when introducing multiple plasmids or cassettes with gentamicin/kanamycin/tetracycline markers.

Transposon or integration workflows: Selection after insertions using combinations of gentamicin, kanamycin, and tetracycline resistance cassettes.

Broad-host cloning applications: Maintenance of tri-marked vectors in Gram-negative hosts such as Pseudomonas or Agrobacterium tumefaciens where all three markers are required.

Starter cultures for scale-up: Seeding bioreactors or larger volumes while preserving tri-marker plasmid integrity.