The construction of recombinant expression strains and the screening of high-performance clones represent the upstream foundation of the master cell bank (MCB) development process. Their purpose is to ensure high-yield, genetically stable strains with excellent passage and storage stability — a critical prerequisite for robust biopharmaceutical manufacturing.
According to pharmacopeia guidelines, master and working seed banks must be fully characterized in terms of their origin, genetic background, and construction process, including documentation for recombinant strain lineage and biological characteristics.
Yaohai Bio-Pharma: Expertise in Recombinant Strain Development
Building on our E. coli and yeast molecular construction platforms, Yaohai Bio-Pharma provides comprehensive services for recombinant strain construction, high-yield clone screening, and standardized material characterization, including plasmid and host cell verification with full traceability and certified Certificate of Analysis (CoA) documentation.
E. coli Expression System
Our E. coli expression platform includes the widely adopted pET vector series, paired with commonly used host strains such as DH5α, TOP10, BL21(DE3), BL21 Star(DE3), and BL21 AI. These systems enable flexible optimization of soluble, inclusion body, or secretory protein expression according to project needs.
Yeast Expression System
For Pichia pastoris (Komagataella phaffii), Yaohai utilizes pPIC9K, pPICZa, and Pinka-HC vector systems, alongside proven host strains such as SMD1168H, X-33, GS115, and PichiaPink strain 1–4, supporting both intracellular and secreted recombinant protein expression.
Key Service Highlights
1. Multi-Host Transformation Platforms
• E. coli: DH5α, TOP10, Trans10, and BL21-derived strains
• Yeast: SMD1168H, X-33, GS115, and PichiaPink strain 1–4
• Clear host lineage with full CoA documentation
• Patent-expired hosts are prioritized to minimize IP risks
2. Regulatory-Compliant Selection Systems
• Antibiotic-free or regulatory-guided selection markers available
• Fully compliant with global regulatory expectations (FDA, EMA, NMPA)
3. High-Throughput Clone Screening
• Platform supports screening throughput of 100+ clones per run
• Rapid identification of high-expression, stable-producing strains
4. Robust Documentation and Traceability
• Comprehensive construction records ensure full process traceability
• Fully aligned with regulatory requirements for recombinant cell line documentation
About Yaohai Bio-Pharma
Yaohai Bio-Pharma is a CRDMO with over a decade of experience in microbial expression systems. Focused on recombinant proteins, nucleic acid drugs, nanobodies, plasmid DNA, and novel vaccines, Yaohai provides full-lifecycle solutions from R&D to commercial manufacturing. The company is committed to building an open and integrated CRO/CDMO/MAH platform that drives innovation from discovery to commercialization, serving as a trusted partner to global biopharma companies.
