Keywords : Hemolysin
Study the effect of the toxin extracted from the E.coli bacteria in the pathogenesis and virulence of E.coli
journal of kerbala university,
Volume 12, Issue 0, Pages 217-227
A local isolation of E.coli bacteria used in these study, and The toxin (Hemolysin) were extracted from it after their culture in the Chemical Defined Media (CDM). Hemolysin extraction was done and partialy purification applied, by using ammonium sulfate. It was found that filtrate contained hemolytic activity at a level higher than that before purification and was the highest dilution gave the hemolytic activity on blood cells 1/32 (320 units / ml)before the partial purification, but after partial purification found that dilution (1/64 ) caused degradation of 50% of the blood cells compared to the standard curve of sodium chloride, LD50 of the mouse for the toxin was calculated and the effect of LD50 of the toxin on the value of LD50 of the bacteria E.coli (non hemolytic) isolated from the stool, The results of the research confirmed role of the toxin on the pathogenesis and virulence of E.coli bacteria through lowering LD50 of this bacteria when injected in the mice with LD50 of the toxin (1.56 micrograms / mL) from (3.16 × 107 cells / mL) to (2.3 × 106 cells / mL).
The injection of different concentrations of the toxin in mice effect on the viability of the mice where the concentration of the toxin that gave hemolytic activity (100, 90%) gave the percentage loss of 100%, while the concentration of the toxin that gave hemolytic activity 50% cause death of of 50% of the mice. Also injection of concentrations different from the toxin, the concentrations that gave hemolytic activity (100,90,70,50,25%), with the lethal dose of the E.coli bacteria is not producing toxin led to increase the proportion of the loss of the mice.