Analysis and prevention of biofilm structure formation generated by escherichia coli on drinking water pumps

A biofilm is an aggregate of microorganisms in which cells adhere to each other and to a living or nonliving surface. Escherichia coli, which is known as coli bacilli, is a member of the bacterial flora of the lower intestine of mammals, can also cause serious diseases. E.coli is used as an ?indicator? of pollution in the water treatment systems. It has the capacity of forming biofilm on surfaces in vivo and in vitro. Within the biofilm structure, it becomes resistant to tough environmental conditions, antibiotics and disinfectants. Thus, the risk of diseases that caused by E.coli, increases.In this study, the structure of experimentally formed E.coli biofilm on the surfaces of the water pumps, have been analyzed by scanning electronic microscope and crystal violet staining on the first, fourth and seventh days. In addition, affects of mechanical and chemical disinfection methods have been studied to solve the problem created by biofilm structure that might threaten the public health. Samples (n: 192) were divided in two groups. Ninety-six samples have been disinfected only by sodium hypochlorite solution (n:48, 500 ppm and n:48, 5000 ppm), while the remaining 96 samples have been first mechanically cleaned by brushing and then disinfected by sodium hypochlorite solution (n:48, 500 ppm and n:48, 5000 ppm). All samples have been analyzed by scanning electronic microscope and crystal violet staining on the first and the forth day of the study. Findings have been compared statistically.As a result, it has been found that E.coli starts forming a biofilm structure on the first day, and builds the densest structure on the fourth day but gradually loses its density on the seventh day. When methods of disinfection were applied, no bacterium was found on the surface of the material. There was no difference between the chemical and physical plus chemical disinfection. In addition, no difference has been observed between the effects of 500 ppm and 5000 ppm sodium hypochlorite solutions. In the light of the foregoing results, it is advisable to use 500 ppm (%0.05) sodium hypochlorite solution every four days for the disinfection of drinking water pumps.