Selective Culture of Escherichia coli: Tri-antibiotic selection and maintenance of transformants carrying gentamicin, kanamycin, and tetracycline resistance markers.

Co-maintenance of Multiple Plasmids: Stable propagation of multi-vector systems with gent/kan/tet selectable markers in Escherichia coli.

Plasmid DNA Preparation: Growth of selective cultures for miniprep/midiprep/maxiprep workflows.

Protein Expression Workflows: Maintenance of expression strains under selection prior to induction and scale-up.

Cloning and Strain Construction: Overnight screening of recombinant colonies in liquid culture with 7/50/10 µg/mL antibiotic levels.

Starter Cultures and Scale-up: Preparation of inocula for flasks/bioreactors under tri-antibiotic pressure.

Glycerol Stock Preparation: Long-term storage of validated selective strains grown in LB with gent/kan/tet.

Antibiotic Resistance Verification: Functional confirmation of resistance cassettes by growth in 7 µg/mL gentamicin, 50 µg/mL kanamycin, and 10 µg/mL tetracycline.

Maintenance of Gram-negative Hosts: Cultivation of engineered Agrobacterium tumefaciens or Pseudomonas spp. carrying compatible resistance markers.