From Methylomes to CRISPR Epigenetic Editing: New Paths in Antibiotic Resistance.

Antibiotic resistance (AR) has long been interpreted through the lens of genetic mutations and horizontal gene transfer. Yet, mounting evidence suggests that epigenetic regulation, including DNA and RNA methylation, histone-like proteins, and small non-coding RNAs, plays a similarly critical role in bacterial adaptability. These reversible modifications reshape gene expression without altering the DNA sequence, enabling transient resistance, phenotypic heterogeneity, and biofilm persistence under antimicrobial stress. Advances in single-molecule sequencing and methylome mapping have uncovered diverse DNA methyltransferase systems that coordinate virulence, efflux, and stress responses. Such epigenetic circuits allow pathogens to survive antibiotic exposure, then revert to susceptibility once pressure subsides, complicating clinical treatment. Parallel advances in CRISPR-based technologies now enable direct manipulation of these regulatory layers. CRISPR interference (CRISPRi) and catalytically inactive dCas9-fused methyltransferases can silence or reactivate genes in a programmable, non-mutational manner, offering a new route to reverse resistance or sensitize pathogens. Integrating methylomic data with transcriptomic and proteomic profiles further reveals how epigenetic plasticity sustains antimicrobial tolerance across environments. This review traces the continuum from natural bacterial methylomes to engineered CRISPR-mediated epigenetic editing, outlining how this emerging interface could redefine antibiotic stewardship. Understanding and targeting these reversible, heritable mechanisms opens the door to precision antimicrobial strategies that restore the effectiveness of existing drugs while curbing the evolution of resistance.