Characterization of Serratia marcescens, S. liquefaciens, S. plymuthica and S. marinorubra by Electrophoresis of their Proteinases

Abstract

Supernatant fluids from 5 day cultures in skim milk nutrient broth of 62 strains of S. marcescens, 24 of S. liquefaciens, 20 of S. plymuthica and 22 of S. marinorubra, together with 27 representative cultures of other genera, were submitted to agar gel electrophoresis. Proteinase activity was demonstrated by the casein-precipitating reaction. S. marcescens produced 1-4 cathodic proteinases and the patterns were in good accord with the classification of strains into biovars. S. liquefaciens often produced anodic and cathodic proteinases with differences between some biovars. S. plymuthica strains produced 1 common cathodic proteinase but no anodic proteinase. Each of the 3 biovars of S. marinorubra produced a specific proteinase. Other bacteria in the study (Erwinia carotovora, E. chrysanthemi and Aeromonas hydrophila) produced proteinases that differed from the Serratia enzymes in their electrophoretic mobility. Proteinase patterns could be useful in the identification of Serratia spp. and biovars.