Dividing lines: compartmentalisation and division in Streptomyces.

Bacteria display diverse strategies for cell division, exemplified by the multicellular life cycle of Streptomyces, a genus within the Actinomycetota phylum. Filamentous growing Streptomyces utilise two distinct division modes: during vegetative growth, nonconstricting cross-walls divide the mycelial network into long multinucleate compartments, while during reproductive growth, sporulation septation results in a ‘multiple division event’ that produces dozens of unigenomic spores that can separate and disperse in the environment. The cellular mechanisms governing these two types of cell division in Streptomyces are inherently complex and present specific biological challenges that involve core cell division proteins and several genus-specific factors. This review highlights recent advances and open questions in our understanding of Streptomyces cell biology, with a focus on key cell division components and the interplay of the chromosome with the division machinery, enabling these organisms to grow as multicellular filaments and form unicellular spores.