LB Agar with Ampicillin (100 µg/mL), Miller Formulation, 20 mL Monoplate, 10/Pk

This product provides 20mL of LB (Luria-Bertani) Agar (Miller Formulation) supplemented with 100 µg/mL of Ampicillin, supplied in sterile petri dishes. This is the standard backbone medium for molecular biology workflows, designed to select for bacteria (typically E. coli) that have been successfully transformed with an ampicillin-resistant plasmid.

The "Selection" Mechanism: LB Agar is the nutrient-rich foundation for molecular cloning, but the addition of the antibiotic transforms it into a screening tool.

1. Miller Formulation: This specific variation (10g/L Tryptone, 5g/L Yeast Extract, 10g/L NaCl) provides the high salt content necessary for optimal membrane transport and osmotic balance during plasmid maintenance.

2. The Antibiotic Barrier: The addition of Ampicillin creates a strict selective environment.

   • The Reaction: Ampicillin inhibits cell wall synthesis in bacteria.

   • The Result: Wild-type E. coli will die on this plate. Only cells that have successfully taken up a plasmid carrying the bla gene (beta-lactamase) can degrade the antibiotic and survive to form colonies.

Usage Note: These plates are frequently used as the base for Blue/White Screening. While the ampicillin ensures that only plasmid-containing cells grow, researchers often add X-Gal and IPTG to the surface to distinguish which plasmids contain the specific DNA insert (white colonies) versus empty vectors (blue colonies).

Common Applications:

• Cloning Verification: Selecting transformants following ligation reactions.

• Plasmid Propagation: Growing specific colonies to isolate plasmid DNA (Mini-preps).

• Strain Maintenance: Preserving laboratory strains that harbor ampicillin-resistant vectors.

Key Features:

• Standard Concentration: 100 µg/mL Ampicillin is the universal standard for plasmid selection.

• High Salt (Miller): Optimized for robust E. coli growth.

• Convenience: Eliminates the cooling/pouring step where heat-sensitive ampicillin often degrades.

• Consistency: Uniform antibiotic distribution ensures reliable selection.

• Format: Sterile pre-poured agar plates (10-pack).

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