Genome rearrangements and megaplasmid loss in the filamentous bacteriumKitasatospora viridifaciensare associated with protoplast formation and regeneration

Abstract

AbstractFilamentous Actinobacteria are multicellular bacteria with linear replicons.Kitasatospora viridifaciensDSM 40239 contains a linear 7.8 Mb chromosome and an autonomously replicating plasmid KVP1 of 1.7 Mb. Here we show that lysozyme-induced protoplast formation of the multinucleated mycelium ofK. viridifaciensdrives morphological diversity. Characterization and sequencing of an individual revertant colony that had lost the ability to differentiate revealed that the strain had not only lost most of KVP1 but also carried lesions in the right arm of the chromosome. Strikingly, the lesion sites were preceded by insertion sequence elements, suggesting that the rearrangements may have been caused by replicative transposition and homologous recombination between both replicons. These data indicate that protoplast formation is a stressful process that can lead to profound genetic changes.RepositoriesGenomic sequence data for strain B3.1 has been deposited in the NCBI SRA database under accession code SAMN11514356.