Release of Surface Enzymes in Enterobacteriaceae by Osmotic Shock

Abstract

The process of osmotic shock, which has been used to release degradative enzymes from Escherichia coli, can be applied successfully to other members of the Enterobacteriaceae. Cyclic phosphodiesterase (3[image]-nucleotidase), 5[image]-nucleotidase (diphos-phate sugar hydrolase), acid hexose phosphatase, and acid phenyl phosphatase are released from Shigella, Enterobacter, Citrobacter and Serratia strains. Some strains of Salmonella also release these enzymes. Members of Proteus and Providencia groups fail to release enzymes when subjected to osmotic shock and do not show a lag in regrowth, although they do release their acid-soluble nucleotide pools. In contrast to E. coli, release of enzymes from other members of the Enterobacteriaceae studied is affected by growth conditions and strain of organism. None of the organisms were as stable to osmotic shock in exponential phase of growth as was E. coli. Exponential phase cells of Shigella, Enterobacter, and Citrobacter could be shocked only with 0.5 mM MgCl2 to prevent irreparable damage to the cells. This group of degradative enzymes is probably loosely bound to the cytoplasmic membrane through the mediation of divalent cations.