Ultra-high electroporation unlocks genetic tools for non-tuberculous mycobacteria

Researchers have long struggled to manipulate the genomes of non-tuberculous mycobacteria (NTM), a group that includes pathogens such as Mycobacterium abscessus. Infections caused by NTM are increasing globally, but tools for probing how these bacteria cause disease, resist drugs, and survive in the environment have lagged behind because getting DNA into the cells is difficult and gene editing succeeds only rarely. In a study led by Qing-Lan Wang, scientists discovered that many NTM tolerate much higher electrical field strengths than previously used for electroporation, and that treating cells with a hypertonic shock before the procedure can partially protect them from electroporation damage. Building on those observations, Wang and colleagues tested an ultra-high electric field strength approach and compared it to standard electroporation conditions. Their goal was simple but ambitious: to make DNA delivery and genome editing in stubborn NTM species efficient enough to support modern genetic experiments, such as making deletion mutants, targeted point changes, and large expression or knockdown libraries.

Electroporation is already effective in some mycobacteria: transformation efficiencies exceeding 10^5 CFU per µg DNA have been reported in Mycobacterium smegmatis and Mycobacterium tuberculosis. But many NTM, including Mycobacterium abscessus, have resisted routine manipulation under standard conditions (1.25 kV/ mm). Using ultra-high electric field strength electroporation (3kV/mm), the team achieved dramatic improvements in plasmid transformation efficiency—up to 10^6-fold in Mycobacterium abscessus, 83-fold in Mycobacterium marinum, and 24-fold in Mycobacterium kansasii—relative to the standard conditions. The authors also found that transformation efficiency depended on the choice of selectable marker. Beyond plasmid uptake, ultra-high field electroporation markedly enhanced genome engineering: allelic exchange in Mycobacterium abscessus expressing Che9c RecET recombinases recovered gene deletion mutants at rates over 1,000-fold higher than conventional electroporation. Oligonucleotide-mediated recombineering for targeted point mutations produced nearly 10,000-fold more mutants under ultra-high field conditions. Together these methodical comparisons show the new settings consistently boost both simple transformation and sophisticated editing workflows.

The practical implications are large. By substantially increasing the ease and efficiency of DNA delivery and genome editing in NTMs, ultra-high field electroporation creates a platform that can support high-throughput functional genomics in species that were previously resistant to genetic manipulation. The approach enables construction of advanced genetic tools described by the authors—expression libraries, CRISPRi knockdown libraries, and genome-wide knockout collections—allowing researchers to systematically probe gene function across entire genomes. Because the method works across multiple NTM species and enhances both allelic exchange and oligonucleotide-mediated recombineering, laboratories can use it to identify genetic determinants of virulence, persistence, and drug resistance. Widespread adoption of ultra-high field electroporation could therefore accelerate discovery of targets for new antimicrobials and vaccines, improve our understanding of clinically important NTM like Mycobacterium abscessus, and open up experiments that were previously impractical due to low editing yields.