Hemolytic activity of Serratia marcescens

A cell-bound hemolytic activity was found in several strains of Serratia marcescens. One Serratia cell per ten erythrocytes was sufficient to cause complete lysis of human erythrocytes within 2 h in the liquid assay. The hemolytic activity resided in the membrane fraction and could be inactivated by incubating cells with proteases. The hemolytic activity was greatly enhanced in actively metabolizing Serratia cells and was partially controlled by the iron supply. Hemolysis was accompanied by degradation of erythrocyte membrane proteins (band 3 and 6, glycophorin) and was independent of the blood group. The exoprotease secreted by S. marcescens in large amounts was not involved in hemolysis. Comparison with various hemolytic strains of Escherichia coli showed that hemolysis of erythrocytes was more pronounced with S. marcescens than with E. coli. In contrast to hemolysis by E. coli, lysis of erythrocytes by S. marcescens was not enhanced by Ca²⁺ ions.Dedicated to Professor Dr. Gerhart Drews on the occasion of his 60th birthday     

A basal-defined medium for the study of proteolytic activity of Serratia marcescens.

A simple defined basal medium is presented for the study of proteolytic activity, induction and repression, and protease purification with Serratia marcescens. Since the medium contains no protein, it does not interfere with or present artifact to protein assays, column chromatography, or electrophoresis. The medium consists of the basal salts and buffer medium of Bromke and Hammel (1979) plus a carbon-energy source such as glycerol, calcium chloride for the cation requirement for protease activity, and an amino acid, preferably leucine. Growth parameters and proteolytic activities are presented for unsupplemented medium and for the medium supplemented with each of 18 amino acids. Unsupplemented medium completes the logarithmic phase in 12.5 h of incubation and has a constitutive level of proteolytic activity. Supplementation with any amino acid, except cysteine and tryptophan, increases significantly the proteolytic activity, but has a varied effect on growth parameters.     

Extracellular haemolytic activity of Serratia marcescens

Blood agar medium with dialysis membrane mounted between two layers of agar was applied to study the haemolytic activity of 28 strains of Serratia marcescens. Two kinds of lytic substances differing with their ability to pass through dialysis membrane were found. Haemolytic activity was not detected in cell-free filtrates from liquid cultures. The discrepancies between haemolytic activity in blood agar media and activity of liquid cultures were observed. Stable attachment of bacterial cells to the erythrocytes was not necessary to lysis. The possibility of extracellular haemolysin is discussed.     

Effect of sodium dodecylbenzenesulfonate and antifoaming agents on the endonuclease activity of Serratia marcescens

The effect of sodium dodecylbenzene sulfonate (sulfonol) and certain froth breakers on the activity of endonuclease was studied in the cultural broth of Serratia marcescens in order to find out whether sulfonol could be used for limiting the infection. Sulfonol was found to have no effect on the cultural growth; it increased the activity of endonuclease in the cultural broth, and the peak of the activity appeared earlier than in the control medium. Propanol B-400 was shown to be the best froth breaker.     

Action of hexaamminecobalt on the activity of Serratia marcescens nuclease

Using CD spectroscopic and kinetic analysis, a refined mechanism of Co(NH₃) ₆ ³⁺ action on activity of Serratia marcescens nuclease was elucidated. The mechanism was identical with previously found mechanisms of Mg²⁺ and C₇H₅O₂Hg⁺. Similarly to Mg²⁺ and C₇H₅O₂Hg⁺, Co(NH₃) ₆ ³⁺ binding to the DNA substrate induced changes in the secondary structure which resulted in changes of the enzymatic activity of the S. marcescens nuclease. Upon binding of 0.03 Co(NH₃) ₆ ³⁺ per DNA phosphate, highly polymerized DNA displayed A-form characteristics. The DNA transition from B-form to A-form intermediate was followed by a decrease of the nuclease activity. The diminishing nuclease activity was consistent with diminishing values of Km and Kcat. Co(NH₃)₆ ³⁺ binding to the highly polymerized DNA caused a 1.7–2.8-fold decrease in Km, and 13.3–19.9 decrease in Vmax compared with Mg-DNA complex. A vast excess of Co(NH₃)₆ ³⁺ did not affect the activity of S. marcescens nuclease if the DNA in the assay mixture remained in its B-form conformation. Preincubation of S. marcescens nuclease with Co(NH₃)₆ ³⁺ did not influence the tertiary structure of the enzyme.     

Cytotoxic activity of Serratia marcescens clinical isolates

Twenty Serratia marcescens isolates from clinical specimens were examined for their cytotoxic activity on four cell lines (HEp-2, Vero, CHO, J774). Most of the isolates were found to be cytotoxic to CHO (70%), Vero (75%) and HEp-2 cells (90%). CHO cells were the most sensitive to cell-free supernatants, followed by HEp-2 and Vero cells. Two strains produced cytotonic toxins which caused elongation of CHO cells. Moreover, twelve isolates (60%) revealed cytotoxic potential to macrophage cell line J774. The results indicate that these bacteria may destroy phagocytes and epithelial cells, which may lead to spread within the host.     

Purification and properties of L-asparaginase from Serratia marcescens

The purification and properties of a tumor inhibitory l-asparaginase from Serratia marcescens are described. The following properties of the enzyme were examined: kinetics of the enzyme reaction, catalytic activity as a function of pH, boundary sedimentation velocity, electrophoresis on polyacrylamide gel, immuno-electrophoresis against homologous and heterologous antisera, immunodiffusion, blood clearance rate in mice, and inhibition of the 6C3HED lymphoma in C3H mice. Complete regression of this tumor was obtained with a smaller dose of the enzyme from S. marcescens than with enzyme from Escherichia coli. The reason for this difference was not evident from a comparison of several properties of the two enzymes.     

Effect of carbon source on the biotransformation enzymesin Serratia marcescens

A microorganism capable of degrading camphor as the sole source of carbon was isolated from soil. The strain was identified as Serratia marcescens (NCIM 5115). The strain when grown in the peptone–glucose medium showed a doubling time of 2.7 h. This microorganism showed the presence of cytochrome P-450, cytochrome b₅ and the activities of cytochrome c reductase, dichlorophenol indophenol reductase, aminopyrine-N-demethylase and steroid 11--hydroxylase. A significant increase in all activities was observed when cells were incubated for 3h in a medium containing either 0.2% camphor, 1.0% n-hexadecane or 0.1% naphthalene when compared to the peptone–glucose medium.     

Polydispersity of Serratia marcescens nuclease at optimal pH values]

Treatment with dimethyl suberimidate, a cross-linking bifunctional agent, showed that Sm1 and Sm2 nucleases of Serratia marcescens B10M1 are polydisperse in solution and consist of monomers and dimers at the level of pH optimal for the enzyme activity. The data suggest that nucleases from the strain B10M1 and any other strain are polydisperse at pH optimum if their amino acid sequences are identical.