SURVIVAL OF PATHOGENIC BACTERIA IN AN ADVERSE ENVIRONMENT

It is know that pathogenic bacteria are sensitive to changes in environmental conditions. This applies to Enterobacteriaceae, as well, where optimum temperature is 37-degrees-C. Wastewater of various qualities are also hostile environments to these bacteria. The aim of the present study was to investigate the influence of temperature on the die-off of enteric bacteria in waste stabilization ponds at the temperature range 40-60-degrees-C. Survival of indicator microorganisms at the control pond effluent was higher than at increased temperature pond effluent (40-degrees-C, 50-degrees-C, 60-degrees-C). Survival percentages of the indicators at the elevated temperature pond compared to the control pond were 0.12% to 73.33%. The pathogenic bacteria Salmonella typhimurium and Shigella sonnie were introduced in dialysis bags placed in the ponds. The number of the pathogenic bacteria decreased by a few orders of magnitude within days, depending on the temperature and the strain. Following certain periods of time, the bacteria held in the heated pond and in some instances in the control pond, lost their ability to agglutinate with specific antibody. The phenomenon of bacteria showing negative specific agglutination requires further research. It is thought that this phenomenon might indicate an unknown heat survival mechanism of the pathogenic bacteria in adverse environment.