Less Is More: Toward a Genome-Reduced Bacillus Cell Factory for “Difficult Proteins”

• DOI: 10.1021/acssynbio.8b00342
• Publication Date: 2018-12-12T20:50:12Z
• Authors: Rocío Aguilar Suárez; Jörg Stülke; Jan Maarten van Dijl
• Keywords: 0301 basic medicine; 570; 0303 health sciences; Genome; Bacterial Proteins/genetics; Bacterial/genetics; Bacillus; Industrial Microbiology/methods; Industrial Microbiology; 03 medical and health sciences; Bacterial Proteins; Metabolic Engineering; Metabolic Engineering/methods; Bacillus/genetics; Genome, Bacterial

The availability of complete genome sequences and the definition of essential gene sets were fundamental in the start of the genome engineering era. In a recent study, redundant and unnecessary genes were systematically deleted from the Gram-positive bacterium Bacillus subtilis, an industrial production host of high-value secreted proteins. This culminated in strain PG10, which lacks about 36% of the genome, thus representing the most minimal Bacillus chassis currently available. Here, we show that this "mini Bacillus" strain has synthetic traits that are favorable for producing "difficult-to-produce proteins". As exemplified with different staphylococcal antigens, PG10 overcomes several bottlenecks in protein production related to the secretion process and instability of the secreted product. These findings show for the first time that massive genome reduction can substantially improve secretory protein production by a bacterial expression host, and underpin the high potential of genome-engineered strains as future cell factories.