BacilloFlex: A modular DNA assembly toolkit for Bacillus subtilis synthetic biology

Abstract

Bacillus subtilis is a valuable industrial production platform for proteins, a bacterial model for cellular differentiation and its endospores have been proposed as a vehicle for vaccine delivery. As such B. subtilis is a major synthetic biology chassis but, unlike Escherichia coli, lacks a standardized toolbox for genetic manipulation. EcoFlex is a versatile modular DNA assembly toolkit for E. coli synthetic biology based on Golden Gate cloning. Here we introduce BacilloFlex, an extension of the EcoFlex assembly standard to B. subtilis. Transcription units flanked by sequences homologous to loci in the B. subtilis genome were rapidly assembled by the EcoFlex standard and subsequently chromosomally integrated. At present, BacilloFlex includes a range of multi-functional B. subtilis specific parts with applications including metabolic engineering, biosensors and spore surface display. We hope this work will form the foundation of a widely adopted cloning standard for B. subtilis facilitating collaboration and the sharing of parts.