Genetic Engineering Techniques in Gram-Negative Bacteria

The ability to manipulate the genetic content of Gram-negative bacteria has evolved into a multifaceted toolkit encompassing conjugative plasmid transfer, electroporation, recombineering and CRISPR-based editing. Conjugation exploits contact-dependent systems to mobilise plasmid DNA across cell envelopes, often utilising broad-host-range vectors and counter-selectable markers to introduce or delete genes in species that are otherwise difficult to transform. Electroporation and chemical transformation remain fundamental for introducing engineered constructs into model organisms such as Escherichia coli, Pseudomonas and Salmonella. Transposon delivery systems and site-specific recombinases facilitate random insertional mutagenesis or targeted chromosomal integration, enabling detailed functional studies of metabolic pathways and regulatory circuits. More recently, CRISPR-Cas systems have been adapted for precise genome editing, supporting allelic exchange, transcriptional regulation and marker-free modifications. Advances in fluorescent tags, orthogonal promoters and synthetic regulatory elements have further refined temporal and spatial control of gene expression. Collectively, these techniques underpin research into pathogenesis, antibiotic resistance, bioproduction and environmental bioremediation, and drive the design of microbial cell factories and rationally attenuated vaccines.

Research from Nature Portfolio

Real-time visualisation of conjugative plasmid transfer in single Gram-negative cells has revealed that DNA enters the recipient cell as single-stranded DNA, which is rapidly converted to double-stranded form at specific subcellular sites. The leading region of the plasmid carries promoters that are active in the single-stranded state, triggering early protein synthesis upon entry. Subsequent double-stranded promoters then drive the expression of maintenance and dissemination factors. This work provides a molecular framework for engineering plasmids with enhanced transfer kinetics and finely tuned gene expression cascades.

Genetic Engineering Techniques in Gram-Negative Bacteria publication trend

The graph below shows the total number of articles in genetic engineering techniques in gram-negative bacteria across all publications each year (not limited to Nature Index journals).

Technical terms

Conjugation: A mechanism of horizontal gene transfer in which plasmid DNA is transferred from a donor to a recipient cell via direct contact and a specialised secretion apparatus.

Plasmid vector: A circular DNA molecule engineered to carry genetic cargo, selectable markers and regulatory elements, often designed to replicate in multiple bacterial hosts.

Relaxase: An enzyme that nicks plasmid DNA at the origin of transfer and remains covalently bound to single‐stranded DNA during conjugation, facilitating translocation.

Counter‐selectable marker: A genetic element, such as sacB, that permits negative selection against cells retaining a vector, enabling seamless allelic exchange or marker‐free genome editing.

References

1. Real-time visualisation of the intracellular dynamics of conjugative plasmid transfer. Nature Communications (2023).
2. Nanopore sensing reveals a preferential pathway for the co-translocational unfolding of a conjugative relaxase–DNA complex. Nucleic Acids Research (2023).
3. Loading and unloading plasmid cargoes. Trends in Microbiology (2024).
4. Chromatic Bacteria – A Broad Host-Range Plasmid and Chromosomal Insertion Toolbox for Fluorescent Protein Expression in Bacteria. Frontiers in Microbiology (2018).