λ Phage Engineering & Genome Editing
OverviewServicesSample RequirementsAdvantagesApplicationsCase StudyFAQs
Overview
Service Overview
With a compact ~48.5 kb dsDNA genome, cohesive-end (cos) packaging sites, and a genetically tractable lysis–lysogeny decision circuit, bacteriophage λ offers an unusually controllable substrate for genome engineering. Decades of research into its repressor–operator logic, site-specific recombination, and transduction have produced a deep molecular toolbox — one we now apply directly to engineering the phage itself.
Creative BioMart Microbe provides λ Phage Genome Editing built on CRISPR-Cas9 counter-selection as the primary approach, supported by BRED (Bacteriophage Recombineering of Electroporated DNA) and in vitro assembly. We edit the λ genome to control the lytic–lysogenic switch, insert genetic cargo, expand host range, and build novel vectors — carrying each project from sequence to validated, scalable phage. Our broader phage genome editing services portfolio spans lytic, temperate, and tool-development platforms.
Whether you need scarless knockouts for life-cycle studies, a J-protein-engineered host-range variant, or a larger-capacity λ vector, our team matches the strategy to your host and goal. Validated edited phages hand off to our phage fermentation and large-scale production service for documentation-ready scale-up.
Figure 1. The λ phage genome editing platform at Creative BioMart Microbe — a genetically tractable λ chassis with defined engineering loci, three complementary editing strategies, and downstream applications, all leading to sequence-verified, plaque-purified deliverables.
Lambda Phage Characteristics & Biological Background
The value of λ as an editing chassis comes from its biology. The table below maps the phage’s defining traits to how we exploit them during engineering.
| Trait |
Detail |
Engineering Relevance |
| Host specificity |
Primarily infects Escherichia coli via the LamB porin receptor |
A defined receptor and host background simplify edit delivery and plaque-based screening |
| Structural features |
Siphovirus morphotype (class Caudoviricetes; the morphology-based family Siphoviridae was abolished in the 2022 ICTV revision): icosahedral head with a long, non-contractile tail; the linear dsDNA genome circularizes through cos sites after entry |
cos sites support in vitro packaging, enabling assembly of recombinant genomes at defined sizes |
| Derived tools |
The λ-Red recombineering system (exo, bet, gam), originally derived from λ, is a widely adopted bacterial genome-editing tool |
Engineering λ in parallel feeds back into improved Red-mediated recombineering across hosts |
| Life cycle |
Lytic and lysogenic states are switched by the cI repressor–Cro regulatory circuit |
A programmable stability switch for controlled prophage induction and cargo delivery |
Services
Service Workflow
Each project moves through a standardized six-step pipeline — from initial consultation and edit design to a deliverable, sequence-verified λ phage — with the strategy customized per target and downstream use.
Editing Strategies
We choose the editing route based on target size, desired scar state, and throughput requirements. CRISPR-Cas9 counter-selection serves as our primary route, while BRED and in vitro assembly address scarless edits and whole-genome recoding needs.
| Strategy |
Mechanism |
λ-Specific Notes |
| CRISPR-Cas9 System (primary) |
Cas9 cleaves unmutated wild-type λ genomes; donor-repaired phages escape cleavage and are strongly enriched among recovered plaques |
Typically reaches high mutant purity without selectable markers; supports scarless single-base and insertion edits |
| BRED (Bacteriophage Recombineering of Electroporated DNA) |
Phage DNA and a mutagenic homologous fragment are co-electroporated into the host, where a recombinase installs the edit |
Ideal for markerless deletions, point substitutions, and small insertions without selectable markers |
| In Vitro Assembly & Rebooting |
Modular isothermal assembly rebuilds the genome in vitro; packaging or electroporation restarts replication |
Enables whole-genome recoding and synthetic λ vector construction beyond intact-genome cloning limits |
Service Details
Gene Knockout / Inactivation
The precise deletion of redundant genes or regulatory elements in λ controls the viral life cycle and isolates gene function. Using CRISPR-Cas9 counter-selection or BRED, we remove early, late, or regulatory loci without leaving resistance markers, then plaque-purify and sequence-verify the mutant. Deliverables include the edited λ and a full editing report, supporting functional and life-cycle studies.
Gene Knock-in / Overexpression
Insertion of exogenous functional fragments or promoter strengthening at non-coding λ loci adds reporter or cargo capacity. We deliver the donor by homologous recombination or isothermal in vitro assembly and select edited phage via Cas9 counter-selection, then validate by PCR and Sanger sequencing. Applications span fluorescent or lux reporters and genetic-cargo delivery. Each project yields plaque-purified, sequence-confirmed λ with documented integration sites.
Point Mutation / Scarless Modification
Single-base substitutions probe key λ proteins such as the cI repressor for thermostability or binding affinity. BRED or CRISPR-Cas9 introduces the change scarlessly, preserving the native genome except the intended nucleotide. We confirm the edit by Sanger sequencing and assess any phenotypic shift in lysogeny or lysis. Deliverables are the pure mutant λ and a concise mutational report.
Multi-Gene Sequential Editing
Synchronous or stepwise modification of multiple λ genome loci builds highly customized engineered phages. We chain CRISPR-Cas9 counter-selection rounds or combine BRED with assembly to edit several targets while controlling the lytic–lysogenic switch. Each intermediate is plaque-purified and sequenced before the next edit. Final deliverables include the multi-edited λ and layered validation records.
Deliverables & QC Standards
- Plaque-purified, high-titer λ lysate.
- Sanger or whole-genome sequencing confirmation of the edit.
- Wild-type background and off-target assessment.
- Host-range and lytic-spectrum characterization where relevant.
- Project report with sgRNA or primer sequences, maps, and methods.
Sample Requirements
To initiate a project, provide as much of the following as possible. Our team will advise on any gaps during the consultation.
| Required Information |
Optional Information |
Not Accepted |
- Target phage (isolated λ lysate or deposited strain) and host E. coli strain
- Desired edit: gene knockout, point mutation, insertion, or host-range change, with target coordinates where known
- Intended application and downstream use (research, therapeutic, industrial)
|
- Existing λ genome sequence or annotation
- Preferred editing strategy or prior attempt data
- Screening or plaque assay protocols you want mirrored
|
- Pathogenic strains restricted by local containment law without prior approval
- Phages requiring BSL-3 handling unless pre-authorized
- Samples lacking any host or sequence context
|
Recommended Input by Edit Type
| Edit Type |
Preferred Input |
Typical Timeline |
| Targeted point mutation / knockout |
λ lysate + E. coli host + target gene |
3–4 weeks |
| Gene knock-in / cargo insertion |
λ + donor design + host strain |
4–6 weeks |
| Host-range (J protein) engineering |
λ + mutant J design or selection scheme |
4–8 weeks |
| Multi-gene sequential editing |
λ + ordered edit plan |
6–10 weeks |
| Novel λ vector construction |
Cargo sequence + packaging constraint brief |
5–9 weeks |
Lysates should be shipped on dry ice with glycerol backups; genomic DNA is accepted in ethanol or TE at 4°C. Contact our team via contact us before sending BSL-2 materials.
Our Advantages
- Fast delivery cycle — A standardized six-step workflow delivers confirmed mutant λ phage within the shortest defensible timeframe for each edit type.
- High-efficiency screening — Our optimized CRISPR-Cas9 counter-selection consistently achieves high mutant-recovery rates across standard λ targets, suppressing wild-type background without markers.
- Scarless, marker-free editing — BRED and CRISPR routes introduce edits without selectable resistance genes, preserving a clean genome for downstream regulatory and therapeutic use.
- Temperate-system expertise — We engineer the lytic–lysogenic switch through cI/antisense and Cas12a circuits, enabling prophage control and programmable cargo delivery.
- λ-Red tool optimization — Beyond editing λ, we optimize phage-derived Red recombinase components and protocols, with recombineering performance validated in E. coli and other bacterial hosts.
- Documentation-ready scale-up — Validated edited phages hand off to phage fermentation and large-scale production under documentation-ready workflows.
Applications
Molecular Tool Optimization
Engineering λ-Red genes (exo, bet, gam) raises recombineering efficiency in E. coli and other bacteria, strengthening a widely used bacterial editing toolkit.
Synthetic Biology Chassis
λ accommodates complex genetic logic gates and reporter genes (lux, fluorescent proteins) for environmental signal sensing and circuit prototyping.
Host-Range Expansion
Tail-fiber J protein engineering redirects λ toward non-standard E. coli strains or closely related species, broadening its reach.
Novel Vector Development
Larger-capacity, more stable λ vectors support gene library construction and screening beyond routine plasmid limits.
Case Study
Case Study 1: CRISPR-Cas12a–Programmed λ Phage for Precision Targeting in Mixed Bacterial Cultures
A 2025 study engineered the temperate phage λ into a precision antibacterial agent by inserting the Lbcas12a gene and a galK-targeting crRNA into the nonessential b2 region of the λ cI857 prophage via homologous recombination. The synthetic phage expressed a functional Cas12a–crRNA complex that cleaved the host galK locus, suppressing lysogeny and driving selective cell death. By truncating the crRNA target-recognition sequence to 16 nt, the phage discriminated single-nucleotide variants, killing cells carrying the perfectly matched target while sparing a strain differing by only one nucleotide. In mixed E. coli cultures, a lacZ-marked version of the phage selectively eliminated the target population to below 1% of viable cells, while non-target cells persisted as lysogens. The study validates the λ b2 region as an insertion site for CRISPR cargo and supports programmable, sequence-specific phage engineering for precision microbiome modulation.
Figure 2. Control of cell death in mixed cell cultures with different galK phenotypes using λ phages carrying the CRISPR-Cas system and lacZ. (Lee, et al. 2025)
FAQs
Q: Why is λ considered the model temperate phage for genome editing?
A: λ is one of the best-understood temperate phages, with a fully sequenced ~48.5 kb genome, defined cos sites, and a well-mapped lytic–lysogenic switch. Its Red recombination system (exo, bet, gam) is itself a widely adopted bacterial editing tool, and the prophage state lets us engineer the genome stably before inducing lysis. That combination makes λ uniquely tractable for precise, reproducible editing.
Q: How does CRISPR-Cas9 counter-selection improve mutant recovery in λ?
A: Cas9 cleaves unmutated wild-type λ genomes during infection, creating powerful negative-selection pressure. Only phages whose genomes were repaired with the donor template escape cleavage, so edited mutants are strongly enriched among recovered plaques — typically reaching high purity and removing the need for resistance markers.
Q: What is BRED and when do you use it for λ?
A: BRED (Bacteriophage Recombineering of Electroporated DNA) co-electroporates λ DNA with a mutagenic homologous fragment into the host, where a recombinase mediates the edit. We use it for markerless deletions, single-base substitutions, and small insertions — especially when you want a scarless edit without CRISPR cargo or when editing loci outside Cas9 accessibility.
Q: Can you engineer the λ lytic–lysogenic switch?
A: Yes. We modify regulatory elements such as cI and antisense circuits, and can install CRISPR-Cas12a prophage systems, to tune when λ chooses lysis versus lysogeny. This supports bacterial gene delivery, synthetic biology chassis, and prophage induction studies where controlled switching is the deliverable.
Q: What host-range expansion is possible by modifying the λ J protein?
A: The distal C-terminal domain of the tail fiber J protein contacts the LamB receptor. We engineer J point mutations or domain swaps so λ recognizes non-standard E. coli strains or closely related species. Because the rest of the genome stays intact, you gain a broader host range while retaining the editing and packaging advantages of λ.
Q: What deliverables and QC do you provide for edited λ phage?
A: Every project delivers plaque-purified, high-titer λ lysate plus Sanger or whole-genome sequencing confirmation of the edit. We assess wild-type background and off-targets, characterize host range and lytic spectrum where relevant, and return a project report with sgRNA or primer sequences, maps, and methods.
Q: How do edited λ phages transition to larger-scale production?
A: Validated edited phages hand off to our phage fermentation and large-scale production service, which operates documentation-ready workflows for research, therapeutic, and industrial scale-up.
References:
- Lee, C. K., et al. (2025). Precision targeting of genetic variations in mixed bacterial cultures using CRISPR-Cas12a-programmed λ phages. Frontiers in Microbiology, 16, 1575339.
