The aims of EBSG are to construct engineered strains and to design production strategies for efficient secretion of native and heterologous proteins from Bacillus subtilis and related industrial micro-organisms

Bacillus species are prolific and commercially important producers of high quality industrial enzymes and of a few high value-added eukaryotic proteins, such as human Interleukin-3. This property is a major reason for their extensive industrial use. However, attempts to secrete heterologous proteins from Bacillus species at commercially significant concentrations have, with few exceptions, met with little success. Until recently, a major problem was the existence of fundamental gaps in our knowledge of the components of the secretion apparatus and their interactions with secretory proteins. Several of these gaps were removed by members of EBSG during the EU Framework 3 and 4 Biotechnology projects (BIO2 CT93 0254 and BIO4 CT96 0097.

As demonstrated by the partnership during the last 6 years, the Bacillus protein secretion machine encodes cellular quality control systems that efficiently remove misfolded or incompletely synthesised proteins. Paradoxically, these quality control systems were shown to represent major bottlenecks for the production of heterologous, high value-added proteins at commercially significant concentrations. Thus, while the inactivation of such quality control systems has the potential to improve the yields of secreted heterologous proteins, this could be achieved at the expense of product quality. An objective of this proposal is to provide an alternative system for the production of heterologous proteins. Currently many of these proteins are produced as inclusion bodies in the cytoplasm of Escherichia coli. This method of produces protein aggregates that contain both contaminating proteins, and misfolded, mistranslated and/or truncated versions of the target heterologous protein.