T7 Phage Engineering & Genome Editing

Q: Do you engineer T7 for expanded host range or drug-resistant strains?

Yes. Engineering the tail-fiber gene gp17 and other receptor-binding elements retargets T7 to specific E. coli derivatives (e.g., defined LPS mutants) or related Gram-negative species. We validate the retargeted host range across the isolates you provide during the consultation.

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OverviewServicesSample RequirementsAdvantagesApplicationsCase StudyFAQs

Overview

Service Overview

T7 bacteriophage is among the most thoroughly characterized virulent phages in molecular biology — a compact ~40 kb double-stranded DNA virus with an exceptionally fast lytic cycle and a fully defined genetic background. Its derived T7 promoter and RNA polymerase system underpin countless protein-expression and synthetic-biology platforms, making it a natural chassis for precise genome engineering.

Creative BioMart Microbe provides T7 Phage Genome Editing built on CRISPR-Cas9 counter-selection, homologous recombination, and in vitro genome assembly. We modify tail fibers, the T7 RNA polymerase, and cargo loci to expand host range, enhance killing, or embed synthetic-biology functions — delivering plaque-purified, sequence-verified phage. Each project pairs the editing strategy to your host strain and research goal.

From rapid bacterial clearance to T7-based surface display and diagnostic engineering, T7's short replication cycle makes it ideal for iterative editing. Our edited phages hand off to phage fermentation and large-scale production for GMP-compatible scale-up. Explore our related phage capabilities to plan a complete development path.

Schematic overview of the T7 phage genome editing platform, showing the T7 virion structure, linear genome map with key editing loci, and the three core editing strategies: CRISPR-Cas9 counter-selection, homologous recombination, and in vitro genome assembly.
Figure 1. Overview of the T7 phage genome editing platform.

T7 Characteristics & Biological Background

T7's compact genome and well-mapped genetics make it unusually tractable for engineering. The table below summarizes the attributes that shape our editing strategy.

Attribute	Description
Structural Attributes	Autographiviridae family with a typical icosahedral head and short tail; linear double-stranded DNA genome of ~39,937 bp.
Molecular Biology Significance	T7 RNA polymerase combines exceptional specificity with high transcription efficiency, anchoring the widely used T7 promoter-based prokaryotic expression system.
Research Model	An ideal model for DNA replication, transcriptional regulation, and viral assembly — among the best-characterized chassis viruses in synthetic biology.
Clinical & Therapeutic Potential	Targeted clearance of E. coli and other pathogenic bacteria in phage therapy; genome editing for host-range expansion or immunogenicity reduction.

Services

Service Workflow

Each T7 project begins with your inquiry and moves through a six-step pipeline, from consultation and design through editing, validation, and delivery. The phage's rapid replication cycle compresses turnaround into a single, efficient project flow.

Horizontal six-step workflow banner for T7 phage genome editing: inquiry and consultation, edit design and plasmid construction, host transformation and donor preparation, Cas9 counter-selection infection and mutant enrichment, plaque purification and sequence validation, and deliverables and scale-up consultation.

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Service Details

3D illustration of a T7 phage genome map with a highlighted non-essential gene region being excised.

Gene Knockout / Large-Fragment Deletion

We delete non-essential T7 genes or excise large genomic fragments to study viral assembly or reduce genome load. Using CRISPR-Cas9 counter-selection, recombineering, or in vitro fragment assembly, we deliver scarless knockouts. Each edited clone is plaque-purified and sequence-verified, with a full editing report.

3D illustration of a T7 phage capsid with a glowing inserted gene payload representing exogenous integration.

Exogenous Gene Integration

We insert reporter genes (e.g., fluorescent proteins) or functional enzyme genes into T7 non-essential regions such as the capsid gene 10B locus. Donor-plasmid homologous recombination or in vitro assembly positions the cargo without disrupting lysis. Deliverables include the integration-confirmed clone and sequencing proof.

3D illustration of a T7 tail fiber protein with a highlighted mutation site representing a precision point mutation.

Precision Point Mutation

We introduce single-base substitutions in tail fiber proteins (gp17) or T7 RNA polymerase active sites to tune host recognition and polymerase behavior. Site-directed donor templates combined with Cas9 enrichment yield scarless point mutants. Each mutant is plaque-purified and validated by whole-genome sequencing.

Service Specifications & QC Standards

Genome Editing Strategies

Strategy	Mechanism	Best For
CRISPR-Cas9 Counter-Selection (core)	Cas9/sgRNA cleaves wild-type genomes during infection; mutants survive and are enriched by negative selection	Point mutations, knockouts, and insertions across the T7 genome with high efficiency
Homologous Recombination	Infection of a donor-plasmid-containing host enables sequence exchange during the infection process	Exogenous integration and medium-size cargo insertion
In Vitro Genome Assembly & Rebooting	Genome is fragmented for point mutation or integration, then electroporated to restart replication	Multi-locus edits, large-fragment replacement, synthetic T7 construction

Deliverables & QC

Plaque-purified, high-titer T7 lysate.
Sanger or whole-genome sequencing confirmation of the edit.
Off-target and wild-type background assessment.
Host-range and lytic-spectrum characterization where relevant.
Project report with sgRNA or primer sequences and methods.

Sample Requirements

To initiate a T7 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 (T7 lysate or deposited strain) and/or host E. coli strain (e.g., BL21) 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 T7 genome sequence or annotation Preferred editing strategy or prior attempt data Screening or bactericidal assay protocols you want mirrored	Pathogenic strains restricted by local containment law without prior approval Phages requiring BSL-3 handling unless prior institutional biosafety approval is obtained Samples lacking any host or sequence context

Recommended Input Format by Edit Type

Edit Type	Preferred Input	Typical Timeline
Precision point mutation	T7 lysate + host strain + target gene/locus	2–3 weeks
Exogenous gene integration	T7 + donor design + host strain	3–4 weeks
Tail-fiber / host-range edit	T7 + multiple E. coli isolates	3–5 weeks
Large-fragment deletion	T7 + host strain + deletion coordinates	3–4 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.

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Our Advantages

High Success Rate — Optimized Cas9 screening pressure ensures precise acquisition of mutants from massive wild-type backgrounds, overcoming the intrinsically low rate of traditional homologous recombination.
Fast Delivery — Leveraging T7's extremely short replication cycle, one round of editing and plaque purification completes within 2–3 weeks.
End-to-End Validation — We deliver a complete verification report from single-plaque screening through whole-genome sequencing, confirming edit accuracy and clonal purity.
Orthogonal Expression Platform — The T7 RNA polymerase promoter system enables edited genomes to drive high-efficiency, orthogonal expression for biosensors and circuit payloads without interference from host transcription machinery.
GMP-Compatible Scale-Up — Validated edited T7 phages hand off to phage fermentation and large-scale production under documentation-ready workflows for therapeutic translation.

Applications

3D isometric illustration of a T7 phage genome with a highlighted non-essential gene representing functional genomics.

Functional Genomics

Precise deletion or modification of non-essential genes, such as early genes, reveals their effects on replication efficiency and the lytic cycle.

3D isometric illustration of a T7 phage releasing a depolymerase to break down a bacterial biofilm.

Phage Therapy Engineering

Integration of depolymerases or fluorescent proteins enhances biofilm degradation and enables real-time infection monitoring of target bacteria.

3D isometric illustration of a T7 phage tail fiber recognizing a specific bacterial receptor representing host-range expansion.

Host-Range Expansion

Tail-fiber protein coding-gene modification enables precise recognition and killing of specific drug-resistant strains and related hosts.

3D isometric illustration of a T7 phage wired into a genetic logic circuit representing synthetic biology.

Synthetic Biology

Engineered T7 phages carrying specific regulatory elements serve as biosensors or novel antibiotic alternatives in programmable circuits.

Case Study

Case Study 1: Continuous Evolution Contracts the Host Range of Bacteriophage T7

A continuous-evolution system coupling a chemostat to a phage-infected lagoon was used to contract the host range of bacteriophage T7. Evolving T7 in the presence of one permissive host and five restrictive strains, each displaying a distinct lipopolysaccharide (LPS) form, repeatedly steered mutations into the receptor-binding protein genes gp17, gp11, and gp12. Sequencing revealed amino acid substitutions clustering at the tip domain of Gp17 and at the phage-proximal regions of Gp11 and Gp12, altering LPS recognition specificity. Evolved specialists infected every restrictive strain at least 1000 times less efficiently than the permissive host, demonstrating that T7 host range can be contracted through receptor-binding protein engineering to exclude non-productive infections while maintaining recognition of the target LPS form.

Line plot showing T7 efficiency-of-plating across six host strains with distinct LPS forms over continuous-evolution time points, demonstrating host-range contraction.
Figure 2. Evolution of phage T7 in the presence of six strains. (Holtzman, et al., 2020)

Case Study 2: Programming CRISPRi to Control the Lifecycle of Bacteriophage T7

CRISPR interference was programmed to control the lifecycle of bacteriophage T7 using Streptococcus pyogenes dCas9 and single or multiplex sgRNAs. Targeting the early promoters A1, A2, and A3 within the non-coding internalisation signal and the T7 RNA polymerase gene gp1 enabled non-invasive manipulation of the phage lifecycle. Individual sgRNAs showed moderate effects on the time to lysis, while multiplex sgRNA arrays targeting multiple regions simultaneously increased the time to lysis by up to 25% and reduced plaque size by up to 8-fold, while the efficiency of plating remained unchanged. This demonstrates that dCas9-dependent CRISPRi can reprogram T7 infectivity without genetic engineering of the phage genome, offering a flexible approach for synthetic biology and biosensor applications.

Bar chart quantifying T7 phage time-to-lysis across single and multiplex sgRNA treatments, showing up to 25% delay with dCas9 induction.
Figure 3. Quantification of the time to lysis of T7 phage. (Bergmiller, 2025)

FAQs

Q: Why is T7 a preferred model for phage genome editing?

A: T7 is an obligately lytic, compact ~40 kb double-stranded DNA phage with an exceptionally fast replication cycle and a fully defined genetic map. Its T7 RNA polymerase promoter system is orthogonal and well characterized, so edits are easy to design, reboot, and validate — making T7 one of the most tractable viruses for engineering.

Q: How does CRISPR-Cas9 counter-selection work on T7, and why is it efficient?

A: During infection, Cas9 guided by an sgRNA cleaves the wild-type T7 genome. Because cleaved genomes cannot replicate, mutants that escape cleavage are enriched by negative selection, while wild-type genomes are progressively depleted. This lifts the intrinsically low mutation rate of traditional homologous recombination toward near-complete mutant recovery in a single round.

Q: Can you introduce precise point mutations in tail fiber or polymerase genes?

A: Yes. We introduce single-base substitutions in the tail-fiber protein gp17 to tune host recognition, or in T7 RNA polymerase active sites to adjust polymerase behavior. Site-directed donor templates combined with Cas9 enrichment yield scarless point mutants, each confirmed by whole-genome sequencing.

Q: What is the typical turnaround for a T7 editing project?

A: Leveraging T7's short replication cycle, one round of editing and plaque purification completes within 2–3 weeks. Exogenous gene integration, tail-fiber/host-range edits, and large-fragment deletions typically require 3–5 weeks. Multi-gene or library projects extend further depending on validation scope.

Q: Do you engineer T7 for expanded host range or drug-resistant strains?

A: Yes. Engineering the tail-fiber gene gp17 and other receptor-binding elements retargets T7 to specific E. coli derivatives (e.g., defined LPS mutants) or related Gram-negative species. We validate the retargeted host range across the isolates you provide during the consultation.

Q: What deliverables and QC come with an edited T7 phage?

A: Each completed project typically includes a plaque-purified, high-titer T7 lysate; Sanger or whole-genome sequencing confirmation of the edit; off-target and wild-type background assessment; host-range or lytic-spectrum data where relevant; and a project report with sgRNA or primer sequences and methods.

Q: How do edited T7 phages transition to larger-scale production?

A: Validated edited T7 phages hand off to our phage fermentation and large-scale production service, which operates documentation-ready, GMP-compatible workflows for therapeutic and industrial scale-up.

References:

Holtzman, T., et al. (2020). A continuous evolution system for contracting the host range of bacteriophage T7. Scientific Reports, 10(1), 307.
Bergmiller, T. (2025). Programming CRISPRi to control the lifecycle of bacteriophage T7. Frontiers in Microbiology, 11, 1497650.

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