A life cycle of branched aerial mycelium- and multiple budding spore-forming bacterium Thermosporothrix hazakensis belonging to the phylum Chloroflexi

Abstract

As far as known, sporulation modes in prokaryotes include formation of endospores exemplified by Firmicutes bacteria, myxospores by myxobacteria and arthrospores by actinomycetes. Here we describe Thermosporothrix hazakensis strain SK20-1^T belonging to the phylum Chloroflexi with a life cycle including a novel prokaryotic sporulation mode. Microscopic observations showed that strain SK20-1^T formed multiple exospores per mother cell by budding in branched aerial mycelia. Although branched aerial mycelia are characteristic of actinomycetes, multiple budding sporulation has not been previously described in prokaryotes. The strain SK20-1^T could be a model microbe for cellular differentiation with multiple budding spore formation.