XS™ Bacillus Expression Systems

  • Introduction

    Bacillus subtilis is the latest strain addition to the Lonza's XS™ Toolbox. This organism has been thoroughly characterized and investigated; its genome has been completely sequenced and all essential genes and metabolic pathways are known. It has also achieved Generally Recognized as Safe (GRAS) status with the US FDA. Currently this organism is widely used for production of prokaryotic industrial enzymes.

    Lonza has developed two XS™ Bacillus Expression Systems for the production of recombinant biopharmaceuticals and vaccines.  XS™ Bacillus is an interesting option to explore for monomeric protein products possessing some intrinsic folding propensity. It is also an attractive host for biopharmaceutical production because it can express soluble properly folded heterologous protein, lacks endotoxin and grows easily to high cell densities in minimal media. These features make recovery and downstream processing easier, more efficient, and improves overall process yields.

    Lonza's XS™ Bacillus Systems Include:

    • Host: Proprietary Bacillus subtilis 168 derivative
    • Two complementary induction approaches: Sugar Inducible and Auto Inducible
    • Over 10 signal sequences to screen
    • Patented high cell density fed-batch fermentation protocols
    • Same multi-cloning site for all plasmids
  • Sugar Inducible

    Lonza’s patented XS™ Bacillus Sugar Inducible System is a positively regulated promoter and is induced by D-mannose. This XS™ System has been successful at expressing proteins in excess of 5 g/L in high cell density fermentations.
  • Auto Inducible

    Lonza’s auto inducible mannose promoter provides an alternative expression approach that eliminates the need for a D-mannose feed. In the XS™ Bacillus Auto Inducible System, induction occurs at the transition from a batch phase into a fed-batch phase. Auto induction takes place as the glucose level falls below a defined concentration. Throughout the fed-batch phase the desired product is expressed as the cells grow to high cell densities. This auto induction strategy often generates higher titers, up to 15 g/L, and offers the added cost-savings from the lack of D-mannose.