This engineered strain is deficient in the uptake of aerobactin, a high-affinity siderophore often associated with bacterial fitness in low-iron environments. It is a targeted modification to reduce the "competitiveness" of the probiotic.
For Research Use Only. Not intended for use in food manufacturing or medical procedures (diagnostics or therapeutics). Do Not Use in Humans.
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Product Information
Product Overview
This engineered strain is deficient in the uptake of aerobactin, a high-affinity siderophore often associated with bacterial fitness in low-iron environments. It is a targeted modification to reduce the "competitiveness" of the probiotic.
Target
Escherichia coli Nissle 1917
Applications
Often combined with other deletions to create a "minimal iron" acquisition profile. This ensures the probiotic remains localized to the gut lumen where iron is more available, preventing it from invading deeper tissues or the bloodstream.
Product Identity & Gene Details
Chassis Strain
Escherichia coli Nissle 1917
Target Gene(s)
iutA
Gene Function
The outer membrane receptor for ferric-aerobactin complexes.
Modification Type
Single gene knockout (Siderophore receptor)
Genetic Architecture
Promoter System
Native promoter
Selection Marker
Standard Antibiotic Marker or Markerless/Scarless (No resistance genes)
Delivery & Service Standards
Deliverables
Glycerol Stocks
Shipping Conditions
Dry Ice Shipping
Lead Time
4-8 weeks
Documents
Certificate of Analysis (COA) or Project Report
Verification
PCR Sequencing
Engineered Strain Recovery & Handling
Immediate Post-Delivery Steps
1. Transfer to Storage: Immediately transfer the cryovials to a -80°C ultra-low temperature freezer. 2. Avoid Fluctuations: Do not store the vials in a "frost-free" freezer, as the temperature cycles can damage the cell membranes of the engineered strains.
Strain Recovery Protocol
To ensure maximum viability, follow this standard recovery procedure: 1. Preparation: Prepare the appropriate selective agar medium (e.g., LB agar + specific antibiotic as listed in the COA). 2. Partial Thawing (The "Scratch" Method): * Place the cryovial on dry ice. Do not thaw the entire vial. Use a sterile inoculation loop or pipette tip to "scratch" a small amount of ice from the surface of the frozen stock. 3. Streaking: Streak the cells onto the selective agar plate to obtain single colonies. 4. Incubation: Invert the plate and incubate at the specified temperature (e.g., 37°C for E. coli or 30°C for S. cerevisiae) for 16-24 hours. 5. Subculturing: Pick a single, well-isolated colony to inoculate into liquid media for your experiments.
Usage Precautions & Best Practices
Antibiotic Pressure
1. Maintenance: For strains containing plasmids or specific resistance markers, always use the correct concentration of antibiotics in both solid and liquid media to prevent plasmid loss or contamination.
2. Markerless Strains: If the strain is a "scarless" integrated knockout, antibiotic pressure is not required for maintenance, but periodic genotypic verification is recommended.
Induction Conditions
1. If your strain uses an inducible promoter (e.g., T7/IPTG or Arabinose), ensure the culture reaches the optimal OD600 (typically 0.6-0.8) before adding the inducer. 2. Verify the optimal induction temperature, as engineered strains often produce better results at lower temperatures (e.g., 16-25°C) to prevent inclusion body formation.
Disposal
All waste (vials, tips, plates) must be autoclaved at 121°C for at least 20 minutes or chemically disinfected before disposal.
