PRODUCTION OF CHOLERA-TOXIN-B SUBUNIT IN LACTOBACILLUS

The intracellular expression of the B subunit of cholera toxin (CTB) w as first achieved in Lactobacillus paracasei LbTGS1.4 with an expressi on cassette including the P25 promoter of Streptococcus thermophilus c ombined with the translation initiation region from the strongly expre ssed L. pentosus D-lactate dehydrogenase gene (ldhD). Secretion of CTB was next attempted in L. paracasei LbTGS1.4 and L. plantarum NCIMB882 6 with four different signal sequences from exported proteins of lacti c acid bacteria (Lactococcus lactis Usp45 and PrtP, Enterococcus faeca lis unknown protein and S. pyogenes M6 protein). Host-dependent secret ion of CTB was clearly observed: whereas none of the secretion cassett es led to detectable CTB in the extracellular fraction of L. paracasei LbTGS1.4, secretion of CTB molecules was clearly achieved with three of the selected signal sequences in L. plantarum NCIMB8826. (C) 1998 F ederation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.