The effect of pH and environmental temperature on the virulence factors of Yersinia spp

Yersinia species are gram negative bacteria that are responsible to cause diarrhea in humans. Due to insufficient knowledge on the effect of pH and temperature in virulence properties of Yersinia spp, this study was conducted to evaluate these factors on virulence properties Yersinia. This was an experimental study performed in two stages on 12 virulence and 7 non-virulence such as Y. enterocolitica, Y. intemedia, Y. fredeniksenii, and Y. kristensenii, which were isolated from different sources. In the first part the impact of pH and temperature on bacterial growth and in the second part of the study the effects of pH and temperature on virulence characteristics of Yersinia spp. were studied by using auto- agglutination test, dependence on calcium, crystal violet, esculin and salicin tests, invasion of Hep-2 cell and RPMI-1640. Temperature and pH were effective on bacterial growth independently without influencing each other. The results showed that temperature was effective on virulence characteristics while pH did not reduce the virulence effect. Furthermore, crystal violet, RPMI-1640 and invasion of Hep-2 cell were more effective in virulence factor. Besides some strains maintained the virulence property during the growth, this might be due to stability of plasmid in such strain. The results showed that both pH and temperature were effective on the growth, but only temperature is effective on virulence properties.