Development of an arabinose-inducible gene expression system for nontuberculous mycobacteria

Nontuberculous mycobacteria (NTM) are emerging pathogens for which genetic tools remain limited. Here, we developed an arabinose-inducible gene expression system based on a modified pBAD24 vector adapted for mycobacterial hosts. The vector carries replication origins for mycobacteria and Escherichia coli, as well as selectable markers compatible with NTM. In Mycobacterium abscessus (Mycobacteroides abscessus), the system enabled dose-dependent induction of target gene expression by arabinose, as demonstrated by increased antibiotic resistance and quantitative RT-PCR analysis. Although basal expression was observed in the absence of arabinose, expression levels were tunable across arabinose concentrations. The system was also functional in Mycobacterium smegmatis (Mycolicibacterium smegmatis) and Mycobacterium bovis BCG, although the degree of basal expression varied among host species. These results establish a tunable inducible expression system for mycobacteria and provide a useful genetic tool for studies of NTM biology.