Multi-Host Expression Systems

Four expression platforms, E. coli, Pichia yeast, baculovirus/insect cells, and mammalian cells: screened in parallel to deliver soluble, functional protein from milligram to gram scale.

Choosing the Right Host

No single host suits every target. NBF runs parallel optimisation across hosts at the start of each project to identify the fastest, highest-yielding route to functional protein.

Platform Strengths Typical Use
E. coli Lowest cost, fastest setup, highest cell densities, mature genetics Single-domain proteins, nanobodies, peptides, soluble cytoplasmic targets
Yeast (Pichia) Eukaryotic post-translational modifications, secreted protein, methanol-induced Secreted proteins, glycoproteins where simpler glycans suffice
Insect (BEVS) Complex post-translational modifications, high success rate for soluble protein Membrane proteins, complex multi-subunit assemblies, virus-like particles
Mammalian Human-like glycosylation, dominant host for therapeutic biologics Antibodies, Fc-fusions, glycoproteins, research-grade and biotherapeutic proteins
Strain panels, vector libraries and detailed condition matrices for each host are listed on the UQ Resource Centre page.

E. coli Bacterial Expression

The fastest, most cost-effective route to recombinant protein. NBF maintains a comprehensive panel of E. coli expression strains: BL21(DE3) and variants (pLysS, CodonPlus-RIL, Star), Rosetta, Arctic Express, Tuner, and the disulfide-friendly Shuffle T7 Express: coupled with a vector library covering pOPIN, pET and pGEX backbones.

Production is supported from screening shake flasks through to twin 10 L stirred-tank fermenters for high-density bacterial cultures. Optimisation parameters include strain selection, induction temperature (37 °C, 30 °C or 15 °C cold-shock), chaperone co-expression, codon optimisation, and media formulation alternatives (TB, 2×YT, chemically defined).

Researcher preparing bacterial expression cultures at the bench

Yeast Expression (Pichia pastoris)

Combining the high cell density and ease of E. coli with the eukaryotic post-translational machinery needed for many secreted glycoproteins. Strain options include PichiaPink (Strains 1–4), GS115, X-33 and KM71H, with vector backbones for both methanol-inducible (AOX1 promoter, pPICZα) and constitutive (GAP promoter) expression.

Standard workflow includes strategy development, electroporation transformation, small-scale clonal screening, and scale-up to 10 L stirred-tank fermenters. Clonal variability assessment is built in by default, the most productive isolate from a panel of independent transformants is carried forward.

Yeast fermentation (Pichia pastoris)

Baculovirus / Insect Cell Expression (BEVS)

For complex eukaryotic targets that won't fold or assemble in E. coli or yeast: virus-like particles, multi-subunit complexes, membrane proteins, and demanding glycoproteins. NBF supports Bac-to-Bac (pFastBac-1, pFastBac Dual), flashBAC, BaculoGOLD and BaculoDirect technologies.

Cell line options span Sf9 (Spodoptera frugiperda), Mimic Sf9 (engineered with mammalian glycosyltransferases for human-like glycans), and High Five™ (Trichoplusia ni). Production scales from shake flask through to a 25 L WAVE bioreactor, with optimisation across cell line, MOI, temperature (typically reduced to 21 °C) and harvest timing (48–72 h post-infection).

Insect cell culture in a single-use bioreactor

Mammalian Cell Expression

The dominant host for therapeutic biologics, and the bridge from research-grade protein to clinical drug substance. NBF's mammalian platform is built around industry-standard CHO and HEK293 cell lines, with vector backbones (pcDNA3.1, pcDNA3.3, pOPIN mammalian) selected for regulatory acceptance and downstream scale-up.

Both transient transfection (rapid, 4–5 days post-transfection) and stable pool / stable cell line development are supported. The Beacon Optofluidics Platform accelerates single-cell cloning by evaluating thousands of clones in parallel, with high-throughput productivity screening and early characterisation feeding clone selection. From there, NBF integrates seamlessly into its own process development and Phase I-enabling manufacturing workflows under an ISO 9001 quality management system.

Mammalian cell culture in biosafety cabinet

Frequently Asked Questions

If a host hasn't been identified empirically for a related target, NBF recommends parallel screening across two or more hosts at the start of the project. As a starting point: simple soluble cytoplasmic proteins typically work best in E. coli; secreted glycoproteins suit Pichia or insect cells; multi-subunit or membrane proteins favour insect cells; and antibodies, Fc-fusions or biotherapeutic candidates are produced in mammalian cells. Many projects ultimately benefit from comparing two hosts head-to-head.
For research-grade material: shake flask up to 20 L for any host system; stirred-tank bioreactors up to 10 L for bacteria and yeast; WAVE rocking-motion bioreactors up to 25 L for insect and mammalian cells. For clinical-grade mammalian production, NBF's manufacturing suite supports up to 50 L bioreactor scale under ISO 9001 quality management.
Approximate timelines from confirmed construct: E. coli screening, 1–2 weeks; small-scale yeast or insect cell expression, 4–6 weeks; transient mammalian expression, 2–4 weeks. Stable mammalian cell line development is the longest workflow, typically 4–8 months depending on protein complexity and required quality attributes.
Transient expression introduces plasmid DNA into host cells to produce protein over days to weeks, ideal for rapid research-grade material. Stable expression integrates the gene of interest into the host cell genome, creating a cell line that consistently produces the protein over many generations. Stable lines are required for large-scale and clinical-supply manufacturing.
CHO (Chinese Hamster Ovary) cells are the most widely used host for commercial production of therapeutic proteins and monoclonal antibodies, with well-characterised regulatory acceptance, robust suspension growth, and human-compatible glycosylation. HEK293 cells offer rapid transient expression and human-style glycosylation, making them ideal for early-stage research and difficult mammalian targets. NBF uses both routinely, often in head-to-head comparison.
NBF maintains access to a range of commercial mammalian cell lines, including Lonza CHO-K1 GS-KO and Thermo Fisher Freedom ExpiCHO. Additional cell lines can be onboarded on request to suit your programme's specific requirements.
NBF and PEF were both recombinant protein research and production facilities based at the University of Queensland. PEF focused primarily on microbial production and non-therapeutic proteins. In 2026, PEF and NBF joined forces under the NBF banner to provide an end-to-end facility for recombinant protein manufacture from multiple expression systems for research, industrial and therapeutic use.

NBF is proudly supported by

NCRIS Therapeutic Innovation Australia The University of Queensland