Genetic and regulatory mechanisms of antibiotic production in microbes

The increasing global crisis of antimicrobial resistance (AMR), projected to maintain 10 million lives annually by 2050, has the discovery of novel antibiotics as a pressing biomedical imperative. Microorganisms, especially actinobacteria of the genus Streptomyces remain the most creative natural sources of clinically applicable to antibiotics, with their biosynthetic potential encoded within discrete genomic loci termed biosynthetic gene clusters (BGCs). The identification of thousands of BGCs through advanced genome mining platforms such as antiSMASH and BiG-SCAPE, a substantial proportion of this biosynthetic repertoire remains transcriptionally silent under conventional laboratory conditions, representing an underexploited reservoir of pharmacological diversity.

Antibiotic biosynthesis is observed by a multilayered regulatory architecture integrating pathway-specific transcriptional activators (e.g., ActII-ORF4, RedD), global regulators (e.g., AdpA, DasR, AfsR), quorum sensing molecules including γ-butyrolactones, and post-transcriptional mechanisms mediated by small regulatory RNAs and riboswitches. The environmental sign mainly carbon catabolite repression and phosphate limitation through the PhoP/PhoR two-component system; exert critical modulation over secondary metabolite output. The synthetic biology approaches, including CRISPR-dCas9-mediated transcriptional activation and heterologous BGC expression, are discussed as transformative strategies for unlocking cryptic clusters.

This mini review aims to combine the recent study on the genetic architecture of BGCs encompassing polyketide synthase (PKS), non-ribosomal peptide synthetase (NRPS), and hybrid biosynthetic machineries and to negatively examine the hierarchical regulatory networks managing antibiotic production, including cluster-situated regulators, global pleiotropic regulators, quorum sensing cascades, and epigenetic mechanisms.