Evaluation of Mycobacterium-derived plasmids for application in oral Actinomyces species

Objectives: Genetic manipulation tools are essential for elucidating the pathogenic mechanisms of microorganisms. Several species of Actinomyces, including A. israelii, are present in the oral cavity and they are the causative agents of actinomycosis. However, efficient gene-editing tools for these species have not yet been developed. In this study, the aim was to evaluate the introduction of foreign genes into Actinomyces using plasmids derived from Mycobacterium, which belong to the same class as Actinomycetes.
Methods: A truncated derivative of pYT923, pYT923S, which contains the replication origin of the M. scrofulaceum plasmid pMSC262 was constructed and introduced into A. israelii by electrotransformation.
Results: pYT923S was successfully introduced into A. israelii. The transformation efficiency of A. israelii was approximately 7–66 CFU/μg of DNA, and all transformed colonies harbored pYT923S. The plasmid recovered from A. israelii replicated in Escherichia coli.
Conclusions: pYT923S was introduced into and maintained within A. israelii. Therefore, the pYT923S vector represents a useful genetic tool for Actinomyces and it is expected to facilitate future studies on the biology and pathogenicity of Actinomyces.