This modification is a "safety-first" engineering step aimed at removing the genotoxic potential of the native Nissle 1917 strain. It ensures that the probiotic can be used long-term in the human gut without the risk of causing DNA damage to the intestinal lining.
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 modification is a "safety-first" engineering step aimed at removing the genotoxic potential of the native Nissle 1917 strain. It ensures that the probiotic can be used long-term in the human gut without the risk of causing DNA damage to the intestinal lining.
Target
Escherichia coli Nissle 1917
Applications
Used in the development of safer probiotic supplements and gut-targeted therapeutics. It retains all the beneficial anti-inflammatory properties of EcN while eliminating concerns regarding its potential link to colorectal cancer.
Product Identity & Gene Details
Chassis Strain
Escherichia coli Nissle 1917
Target Gene(s)
clbA
Gene Function
An essential enzyme for the synthesis of colibactin, a secondary metabolite that can cause double-strand DNA breaks in eukaryotic cells.
Modification Type
Single gene knockout (Toxin biosynthesis inactivation)
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.
