Production of Antibody Fragments in the Gram-Positive Bacterium Bacillus megaterium

For many applications antibody fragments like scFv or Fab are an alternative to full size IgGs. These fragments can be produced in bacterial host systems, which are less time and cost intensive than mammalian cell culture, the production host for more complex IgGs. The Gram-negative bacterium Escherichia coli has been employed for the production of recombinant antibody fragments for over 20 years, but certain disadvantages could not be eliminated, such as its inefficient secretory capacity due to its outer membrane. The Gram-positive, apathogenic soil bacterium Bacillus megaterium has been studied for the secretion of antibody fragments directly into the culture medium, thereby easing the downstream processing. Here, we describe the production of antibody fragments in B. megaterium, from preparation of protoplasts for transformation to purification of the recombinant protein by IMAC