Biology 11th Edition by Cecie Starr ,Ralph Taggart

تمرين 2

Annual costs of treating known cases of food poisoning are between 5 billion and 22 billion dollars, and pathogens in kitchens may cause at least half of the cases. Electron microscopes show microbes on wood or plastic cutting boards, even stainless steel knives. Carlos Enriquez and his colleagues at the University of Arizona sampled 75 dishrags and 325 sponges in some homes. The found Salmonella , E. coli , Pseudomonas , and Staphylococcus colonies in most of them. Bacteria can live for as long as two weeks in a wet sponge (which can be sanitized in one dishwasher cycle). If your class has access to a good light microscope, each of you bag one of your kitchen sponges or dishrags and compare what might be living with you.