<jats:title>Summary</jats:title><jats:p>The secreted γ‐butyrolactone signalling molecule <jats:styled-content style="fixed-case">SVB1</jats:styled-content> regulates the biosynthesis of jadomycin in <jats:styled-content style="fixed-case"><jats:italic>S</jats:italic></jats:styled-content><jats:italic>treptomyces venezuelae</jats:italic>. Interestingly, this molecule is identical to <jats:styled-content style="fixed-case">SCB3</jats:styled-content>, a secreted regulator of secondary metabolism in <jats:styled-content style="fixed-case"><jats:italic>S</jats:italic></jats:styled-content><jats:italic>treptomyces coelicolor</jats:italic>. This is a departure for this class of signalling molecules as there are no previous reports of identical signalling molecules produced in different species. One implication of this work is that different species of bacteria could use shared extracellular signals to co‐ordinate secondary metabolism when and if it is advantageous to do so.