Properties of the Hemolytic Activities of Escherichia coli

Abstract

Some properties of the cell-free and cell-associated hemolysins of Escherichia coli were studied. Several strains of E. coli that were isolated from intestines of pigs with edema disease produce large quantities of cell-free hemolysin when grown in the presence of an extract of meat. The component of meat that stimulates production of cell-free hemolysin is not extracted by lipid solvents and is not dialyzable. The cell-free hemolysin is an acidic substance that occurs in two forms. It is inactivated by trypsin but not by lecithinase, lysozyme, ribonuclease, or deoxyribonuclease, shows optimum activity between pH 7 and 8, and requires calcium ion for activity. It does not appear to be an enzyme. The kinetics of the lytic reaction are most consistent with the hypothesis that one molecule of cell-free hemolysin is sufficient to lyse one erythrocyte and that it is inactivated in the lytic reaction. The cell-free hemolysin does not sufficiently damage the cell during the prelytic period to cause lysis after the hemolysin-calcium-erythrocyte complex has been disrupted. The cell-associated hemolysin was not separated from the cell by autolysis, freezing, sonic treatment, or treatment with trypsin or lysozyme. It appears to be closely associated with the metabolic status of the cell. Organisms that are highly hemolytic under usual conditions of assay immediately lose most of their hemolytic capability in the presence of sodium cyanide, streptomycin, nalidixic acid, and rifampin.

Study of haemolytic activity of some Campylobacter spp. on blood agar plates

“…Sakazaki et al (1971) found that basal media containing a high content of animal tissue extracts sthulated haemolysis by V. cholerae in culture. Similar observations of increased haemolysin production by E. coli in media containing animal tissue extracts were made by Short & Kurtz (1971). It appears that, as with V. cholerae or E. coli, the campylobacters have complex requirements to stimulate haemolysis in culture.…”

“…Peptones and extracts from animal tissue stimulate haemolytic activity or production of haemolysin in culture media by certain Gram-negative bacteria, e.g. eltor strains of Vibrio cholerae (Sakazaki et al 1971) and strains of Escherichia coli (Short & Kurtz 1971). It was therefore decided to use Heart Infusion (HI; Difco) and Brain Heart Infusion (BHI; Oxoid) which both contain high concentrations of animal tissue extracts, to study haemolytic activity of the campylobacters.…”

Genetics of hemolysin of Escherichia coli

“…Alpha-hemolysins expressed by E. coli from a variety of sources are antigenically cross-reactive (33) and have similar, although not identical, physical properties. They are, in general, heat labile (4,18,27,33,38,42), acidic (21,27,31) proteins (18,27,31,42) with a molecular weight of 58,000 (10) to 120,000 (41). They require Ca2+ for full activity (28,31,39) and are most active at pHs 7 to 8 (31,42).…”

Domains of Escherichia coli hemolysin (HlyA) involved in binding of calcium and erythrocyte membranes

“…HlyA is thought to lyse cells by forming pores in the membranes of target cells (2)(3)(4)15). The hemolytic activity of HlyA is calcium dependent (1,28,29,31). In a preceding paper, we demonstrated that the binding of E. coli hemolysin to erythrocytes is calcium dependent (5).…”