Characterisation of a Pasteurella multocida esterase gene which confers a hemolytic phenotype in Escherichia coli under anaerobic conditions

Investigation of the hemolytic phenotype under anaerobic growth conditions of an avian Pasteurella multocida strain, PBA100, resulted in the identific ation and characterisation of a gene encoding an esterase enzyme, mesA, tha t conferred a hemolytic phenotype in Escherichia coli under anaerobic condi tions. MesA appeared to be expressed and functional under anaerobic and aer obic conditions in both E. coli and P. multocida. A P. multocida mesA mutan t was generated which resulted in the loss of acetyl esterase activity unde r anaerobic conditions. However, this mutation did not cause any attenuatio n of virulence for mice nor a detectable change to the anaerobic hemolytic phenotype of P. multocida. In E. coli MesA appeared to cause hemolysis indi rectly by the induction of the latent E. coli K-12 cytolysin, sheA. (C) 200 0 Federation of European Microbiological Societies. Published by Elsevier S cience B.V. All rights reserved.