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bioRxiv · 10.1101/2025.06.04.657955

Ultra-high field strength electroporation enables efficient DNA transformation and genome editing in nontuberculous mycobacteria

Tang, D.·Wang, M.-G.·Wang, D.·Yang, D.·Cai, Y.·Luo, T.·He, J.-q.·Wang, Q.
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Abstract

Efficient DNA delivery is essential for genetic manipulation of mycobacteria and for dissecting their physiology, pathogenesis, and drug resistance. Although electroporation enables transformation efficiencies exceeding 105 CFU per {micro}g DNA in Mycobacterium smegmatis and Mycobacterium tuberculosis, it remains highly inefficient in many non-tuberculous mycobacteria (NTM), including Mycobacterium abscessus. Here, we discovered that NTM such as M. abscessus exhibit exceptional tolerance to ultra-high electric field strengths, and that hypertonic preconditioning partially protects cells from electroporation-induced damage. Using ultra-high electric field strength (3kV/mm) electroporation, we achieved dramatic improvements in plasmid transformation efficiency--up to 106-fold in M. abscessus, 83-fold in Mycobacterium marinum, and 24-fold in Mycobacterium kansasii--compared to standard conditions (1.25 kV/ mm). Transformation efficiency was further influenced by the choice of selectable marker. Ultra-high field strength electroporation also markedly enhanced allelic exchange in M. abscessus expressing Che9c RecET recombinases, increasing recovery of gene deletion mutants by over 1,000-fold relative to conventional electroporation. In parallel, oligonucleotide-mediated recombineering for targeted point mutations produced nearly 10,000-fold more mutants under ultra-high field conditions. Together, these findings establish ultra-high field electroporation as a robust, broadly applicable platform for genetic engineering of NTMs. This method substantially enhances transformation efficiency and enables construction of advanced genetic tools--including expression libraries and CRISPRi knockdown libraries--in species that have historically resisted genetic manipulation. ImportanceInfections caused by non-tuberculous mycobacteria (NTM), including Mycobacterium abscessus, are increasing globally, yet genetic manipulation of these pathogens remains technically challenging due to inefficient DNA delivery and low gene editing success. The ultra-high electric field strength electroporation strategy described here overcomes these barriers, enabling dramatic improvements in both transformation and genome editing efficiency. This advance paves the way for high-throughput functional genomics in NTMs, including the construction of genome-wide knockout, CRISPRi knockdown, and expression libraries. Broad adoption of this approach will accelerate discovery of genetic determinants of virulence and drug resistance, facilitating the development of antimicrobials and vaccines.

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Tang, D., Wang, M.-G., Wang, D., Yang, D., Cai, Y., Luo, T., He, J.-q., Wang, Q.. 2025-06-06. Ultra-high field strength electroporation enables efficient DNA transformation and genome editing in nontuberculous mycobacteria. https://doi.org/10.1101/2025.06.04.657955

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