Isolation and characterization of Francisella novicida mutants defective in lipopolysaccharide biosynthesis

In order to identify genes involved in LPS biosynthesis we isolated random mutants generated by transposon insertion in Francisella novicida. The resu lting mutant bank yielded mutants with three distinct LPS phenotypes, and t hree representative mutants were chosen for further study. One mutant that had short O-antigen chains was sensitive to serum; this mutant and one othe r were more sensitive to killing by deoxycholate than control strains. The third mutant was resistant to deoxycholate killing but slightly sensitive t o serum. The three mutants varied in their ability to grow in macrophages. The DNA sequences interrupted by the transposon in two of the three mutants showed similarity to known LPS biosynthetic genes at the deduced amino aci d level. (C) 2000 Federation of European Microbiological Societies. Publish ed by Elsevier Science B.V. All rights reserved.