Competence repression by the SPβ prophage in Bacillus subtilis revealed by transcriptomics across culture conditions

SPβ prophage in Bacillus subtilis is strongly induced by competence, and competence-inducing conditions show reduced competence gene expression and transformation efficiency in SPβ lysogens.

• Why it matters: Prophage effects are usually tested only under limited lab stresses, leaving unclear which ecological states trigger prophage–host interaction and how it shapes host DNA uptake.
• What they did: Using publicly available transcriptomes, the authors identified competence as a driver of prophage gene expression, then compared SPβ lysogens versus cured or non-lysogenic strains under competence-inducing conditions with transformation assays and a late competence transcriptional reporter.
• The result: In competence-inducing conditions, both SPβ lysogen strain sets showed lower competence gene expression than non-lysogenic counterparts, matching reduced transformation efficiency and reporter activity, implying prophage repression constrains host DNA uptake and evolvability.

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