Comparative transcriptional analysis of Bacillus subtilis cells overproducing either secreted proteins, lipoproteins or membrane proteins.

Background: Bacillus subtilis is a favorable host for the production of industrially relevant proteins because of its capacity of secreting proteins into the medium to high levels, its GRAS (Generally Recognized As Safe) status, its genetic accessibility and its capacity to grow in large fermentations. However, production of heterologous proteins still faces limitations.

Results: This study aimed at the identification of bottlenecks in secretory protein production by analyzing the response of B.

A novel screening system for secretion of heterologous proteins in Bacillus subtilis.

High-level production of secretory proteins in Bacillus subtilis leads to a stress response involving the two-component system CssRS and its target genes htrA and htrB. Here, we used this sensing system in a reporter strain in which gfp is under control of P(htrA) , the secretion stress responsive promoter of htrA. Overexpression of heterologous secretory proteins in this strain results in green fluorescent cells, which can be separated from non-secreting, low fluorescent cells using a fluorescence-activated cell sorter (FACS).