E. coli Expression System

The E. coli expression system holds its reputation as the most widely employed and cost-effective method for recombinant protein expression. Its simplicity in structure, well-defined genetic background, ability to achieve exceptionally high target protein yields, and short cultivation periods contribute to its widespread adoption across basic research and industrial bioprocessing.

Why Pick the E. coli Expression System?

• Cost-Effective E. coli is relatively inexpensive to culture compared to eukaryotic systems, making it ideal for budget-conscious and large-scale protein production.
• High Yield Capable of producing high quantities of recombinant proteins—often comprising a significant proportion of total cellular protein.
• Speed & Rapid Turnover A fast growth rate and short generation time allow for quick turnaround from gene synthesis to purified protein, supporting high-throughput screening.
• Simple Culture Conditions Grows reliably in standard, inexpensive media under conventional laboratory conditions without requiring specialized fermentation equipment.
• Fusion Tag Compatibility Amenable to a broad array of fusion tag systems (e.g., His, GST, MBP) that improve target solubility, assist in detection, and simplify purification.
• Broad Versatility Versatile enough to express a wide variety of targets, including soluble cytoplasmic proteins, enzymes, and non-complex eukaryotic fragments.

Service Process & Deliverables

1. Plasmid Construction

15 – 20 Days

Workflow Process

• Codon optimization and custom gene synthesis
• Restriction digestion of PCR products and vector ligation
• Transformation into TOP 10 competent E. coli cells
• Colony screening and sequence confirmation

Key Feature

Vector Optimization: We simultaneously evaluate multiple expression vectors and fusion tags to determine which construct achieves the highest expression yield.

2. Transformation & Screening

5 Days

Workflow Process

• Transformation of recombinant plasmid into production hosts
• Single-colony small-scale induction testing
• SDS-PAGE expression verification and clone selection
• Preservation of superior high-yielding colonies

Key Feature

Parameter Tuning: Induction temperatures, IPTG concentrations, and host strains (e.g., BL21, Rosetta) are fine-tuned during preliminary trials to establish optimal culture conditions.

3. Scale-Up & Purification

12 – 15 Days

Workflow Process

• 1 L to 10 L large-scale fermentation culture expansion
• Cell lysis and clarification of soluble supernatant
• Chromatographic purification (Affinity, IEX, SEC)
• Buffer exchange into user-defined storage buffers

Key Feature

Multi-Condition Chromatography: We screen different chromatographic resins and wash profiles to establish an optimal purification method tailored to your target.

4. Inclusion Body Renaturation

5 Days

Workflow Process

• Inclusion body isolation and solubilization (if required)
• Refolding buffer formulation and screen testing
• Renaturation via dilution, dialysis, or column methods
• Refolded monomer purification and stabilization

Key Feature

Different buffering matrices are swiftly evaluated to recover bioactive protein, consistently attaining refolded target purity levels surpassing 90%.

5. Optional Downstream Services

3 – 5 Days

Available Options

• Endotoxin removal (<0.1 EU/µg or <0.01 EU/µg thresholds)
• Aseptic processing and 0.22 µm filter sterilization
• Lyophilization for extended storage stability
• Enzymatic tag cleavage and removal (additional fee)

Key Feature

Select from a flexible menu of optional downstream treatments designed to prepare your recombinant protein for sensitive in vitro or cell-based assays.

6. Quality Control & Release

5 Days

Workflow Process

• Purity determination via SDS-PAGE and HPLC (>85% to >98%)
• Accurate concentration quantification (BCA or A280)
• Endotoxin testing (if requested)
• Final lot packaging and shipment preparation

Key Feature

Every completed project is delivered with a detailed Certificate of Analysis (COA) documenting experimental QC data and analytical chromatograms.

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