Purification & characterisation of haemolysin from Serratia marcescens B-91

Background & objectives : Serratia marcescens an opportunistic human pathog en, is frequently encountered in a variety of debilitating diseases. Relati vely little is known about its virulence traits though mast clinical isolat es secrete a distinct haemolysin which is considered asa useful marker for pathogenicity of Serratia. In this study purification and characterisation of S. marcescens B-91 haemolysin have been attempted. Methods : S. marcescens B-91 haemolysin was purified to homogeneity from th e growth medium using ammonium sulphate fractional precipitation and gel fi ltration through Sephadex G-75 column. Homogeneity was determined by gel el ectrophoresis and purified haemolysin was tested for its stability and othe r characteristics. Results : The haemolysin was characterised to be a 45 kDa molecular weight protein on SDS-polyacrylamide gel electrophoresis. It was inactivated at 60 -100 degreesC within 30 min, and on overnight treatment with 2 per cent for maldehyde, It was also susceptible to the action of pronase, protease and t rypsin. Interpretation & conclusions : The results indicate that the fragile stabil ity of S. marcescens haemolysin is dependent on the storage temperature, Th e purified haemolysin can be used for understanding the role of haemolysin in the pathogenesis of S. marcescens and also for evaluation of immunoproph ylactic activity.