Bacteroides Gene Editing Service
1. ResearchBackground
Bacteroides are the most abundant and representativeobligate anaerobic Gram-negative bacteria in the human gut microbiota. Theyplay critical roles in polysaccharide metabolism, host immune systemregulation, and colonization resistance. With deeper insights into themicrobiota–gut–brain axis and symbiotic mechanisms, precise and efficient geneediting technologies have become essential tools for dissecting Bacteroidesfunctional genes, developing engineered probiotics, and exploring therapeuticstrategies.
Against thisbackground, Shutong Biotech provides Bacteroides-targeted gene editingsolutions based on CRISPR/Cas and suicide plasmid-mediated homologousrecombination. We offer customized services for gene knockout, point mutation,and gene integration (overexpression) in various Bacteroides species,including Bacteroides thetaiotaomicron, Bacteroides fragilis, andothers, with verified positive mutant strains delivered. We are committed toproviding professional and reliable Bacteroides genome engineeringsolutions for global research clients.
2. StrainCharacteristics and Biological Background
(1) Gram StainProperty: Bacteroides are typical Gram-negative bacteria.
(2) Morphologicaland Physiological Traits: Obligately anaerobic, non-spore-forming, andpossessing complex capsular polysaccharide structures. Their outer membranecontains unique lipopolysaccharide (LPS) distinct from that of common entericpathogens.
(3) Clinical andEcological Significance: They are major carbohydrate-degrading bacteria inthe gut. While most are commensal, species such as Bacteroides fragilisare clinically relevant in intra-abdominal infections.
(4) Metabolismand Applications: Equipped with powerful polysaccharide utilization loci(PULs), Bacteroides serve as an ideal model for studying gut symbiosis,complex carbon metabolism, and host–microbe interactions.
3. Reported EditingStrategies in Literature
To address thechallenges of obligate anaerobiosis and low transformation efficiency in Bacteroides,mainstream strategies reported in literature include:
3.1 CRISPR/CasSystems (e.g., Cas9 or Cas12a)
(1) Mechanism:Cas proteins are guided by sgRNAs to perform precise cleavage of the targetgenome.
(2) Advantages:As a powerful counter-selection tool, it greatly improves the efficiency ofmarker-free editing, especially for large-fragment deletions or geneintegration.
3.2Counter-selection Systems
Suicide plasmidsharboring the tdk gene are commonly used, combined with5-fluorodeoxyuridine (FUdR) for counter-selection to achieve precisechromosomal replacement.
3.3 Conjugation
To overcome unstableelectroporation efficiency in Bacteroides, Escherichia coli(e.g., S17-1) is typically used as a donor strain to efficiently deliverediting plasmids into recipient Bacteroides via conjugation.
3.4 TransformationEfficiency Optimization
For different Bacteroidesspecies, conjugation time, donor-to-recipient ratio, and medium components areoptimized to overcome entry barriers caused by thick capsules.
4. Core ApplicationAreas
(1) FunctionalGenomics: Precise deletion of polysaccharide utilization loci (PULs) toinvestigate competitive advantages in the complex intestinal environment.
(2) Host–MicrobeInteractions: Knockout of virulence factors or surface polysaccharidesynthesis genes to dissect regulatory mechanisms on the intestinal immunesystem.
(3) SyntheticBiology Chassis Construction: Insertion of therapeutic protein expressioncassettes at safe genomic loci to develop novel “living biotherapeutic product”delivery systems.
(4) MetabolicPathway Engineering: Optimization of short-chain fatty acid (SCFA)synthesis pathways via gene overexpression or point mutations.
5. Project Workflowand Validation
We provide one-stopservices from design to delivery to ensure accurate editing results:
(1) ProtocolDesign and Vector Construction: Design of knockout plasmids targeting Bacteroidesloci.
(2) BacterialTransformation and Screening: Overcome difficulties in obligate anaerobetransformation and screen integrated clones.
(3) SecondRecombination and Resolution: Induce second recombination viacounter-selection or CRISPR cleavage.
(4) MultilevelValidation: Positive mutants are confirmed by PCR identification and Sangersequencing.
6. Gene EditingProject Introduction
6.1 Core Services
(1) Gene Knockout/ Inactivation
Precise deletion ofspecific metabolic or signaling pathway genes for gene function research.
(2) Gene Knock‑in/ Overexpression
Integration ofreporter genes (e.g., fluorescent proteins) or functional genes at definedchromosomal loci.
(3) Marker‑freeEditing
No introduction ofantibiotic resistance markers, enabling iterative multiple rounds ofmodification in the same strain.
(4) MultigeneEditing
Sequential orsimultaneous editing of multiple metabolic targets for construction of complexengineered strains.
6.2 TechnicalAdvantages
(1) ExtensiveExperience
Covers major Bacteroidesspecies including B. thetaiotaomicron (Bt), B. fragilis (Bf), andB. vulgatus (Bv).
(2) CustomizedDesign
Optimized strategiestailored to research goals such as polysaccharide metabolism and intestinalcolonization.
(3) ComprehensiveValidation
Detailed sequencingreports and genotyping identification results are provided throughout theproject.
7. Case Study
Development of aCRISPR/Cas‑Based Genome Editing Tool for the Human Gut Commensal Bacteroides
(1) ResearchBackground
Bacteroides is the most abundant genus in the human gutmicrobiome (accounting for 20–30% of gut microbiota), and plays a key role inmaintaining intestinal health, metabolic regulation, and immune homeostasis.
Dysfunction of Bacteroidesis closely associated with obesity, inflammatory bowel disease, colorectalcancer, and other disorders.
Although Bacteroidesrepresents an ideal model for studying gut microbial functions, its geneticengineering tools remain limited:
Methods such as NBUtransposon mutagenesis and allele exchange suffer from low editing efficiency,rely on selectable markers, and do not support marker‑free editing.
While CRISPR/Cas hasbeen widely adopted in other bacteria, optimized systems for strictly anaerobicBacteroides remain underdeveloped.
There is an urgentneed for efficient editing tools to dissect Bacteroides gene functions(e.g., polysaccharide utilization loci, PULs), metabolic pathways, andecological roles in the gut.
This study aims tofill this gap by establishing a CRISPR/Cas system for precise, marker‑freegenome editing in Bacteroides.
(2) ExperimentalDesign
The research teamdesigned an all‑in‑one plasmid system integrating CRISPR/Cas components,homologous repair templates, and host‑adapted elements.
Key design features:
CRISPR System Selection
Three Cas proteinswere evaluated for editing efficiency: FnCas12a (T‑rich PAM), SpRY (near‑PAMless),and SpCas9 (canonical system).
Cas expression wascontrolled by inducible promoters (e.g., aTc‑inducible P1TDPGH023) to avoidtoxicity from constitutive expression.
Plasmid Construction and Delivery
A Bacteroides–E.coli shuttle vector was constructed and delivered into Bacteroidesvia conjugation.
sgRNAs were designedto target specific genes (e.g., Bt1754), with homology arms for template‑directedrepair.
Optimized Workflow
A five‑stepprocedure was established: plasmid construction, conjugation, Cas induction,mutant screening, and plasmid curing.
Key Assays
Promoter activitywas evaluated using a luciferase reporter system; the inducible P1TDPGH023promoter outperformed constitutive promoters.
Species‑specificsgRNAs were designed for diverse Bacteroides species including B.thetaiotaomicron and B. fragilis.
(3) ExperimentalConclusions
Editing Efficiency and Optimization
The FnCas12a systemachieved the highest efficiency: 60% for gene deletion in B.thetaiotaomicron, compared to 40% for SpRY and SpCas9.
Inducible promotersimproved editing efficiency by more than 10‑fold over constitutive promoters.
Large‑Fragment Deletion
The systemsuccessfully deleted PUL clusters up to 50 kb (e.g., RGI‑PUL), with nearly 100%efficiency for 5–10 kb deletions.
Multifunctional Validation
GFP reporter geneknock‑in reached over 80% efficiency, enabling fluorescent labeling.
The systemfunctioned across species, with 60–100% efficiency in B. fragilis, B.ovatus, B. uniformis, and B. vulgatus.
Deletion ofmetabolic genes such as Bt1754 impaired growth on fructose media,confirming gene function.
Plasmid curingenabled iterative editing without residual antibiotic markers.
(4) ApplicationSignificance
Scientific Value
Provides a precisetool for investigating Bacteroides PUL metabolic networks andhost–microbe interactions, clarifying the role of polysaccharide degradationpathways in gut ecology.
Supports multiplexgene editing and accelerates functional genomics research.
Biotechnological Applications
Enables engineeringof strains with enhanced colonization capacity and delivery of therapeuticmolecules (e.g., anti‑inflammatory factors) for metabolic disease treatment.
Facilitates gutmicrobiome engineering and lays the foundation for synthetic microbialconsortia and controlled intestinal environments.
Technical Advantages and Future Outlook
Highly efficient:editing cycle shortened to 2–3 weeks, greatly outperforming traditionalmethods.
Broadly applicable:compatible with multiple Bacteroides species, promoting standardizationin gut microbiota research.
Future integrationwith base editing and transcriptional regulation will further enable precisioncontrol of gut microbes.
WorkWith Us
Partner with us, and you will gain a highlyexperienced and technically proficient gene editing collaborator.
We are committed to accelerating your researchand projects with professional expertise, rigorous workflows, and efficientcommunication.
Contact us today for your customized geneediting strategy and quotation!
