Chemical mutagenesis of M. haemolytica strain TI619

Mannheimia haemolytica is one of the bacterial agents responsible for bovine respiratory disease (BRD). The capability of M. haemolytica to form a biofilm may contribute to the development of chronicBRD, and as a result, be more resistant to host innate immunity and antibiotics. A greater understanding of the association between M. haemolytica surface components and biofilm formation is needed to improve therapy and prevent BRD. Wild-type M. haemolytica made a poorly adherent and low-biomass, but aggregative biofilm. To examine the relationship between capsule and biofilm formation, a capsule-deficient mutant of M. haemolytica strain TI619 (mutant E09) was obtained following mutagenesis with ethyl methanesulfonate. The site of mutation was confirmed by sequencing and complemented in trans.