Isolation, Enumeration, Identification and Confirmation of Lab Report

Isolation, Enumeration, Identification and Confirmation of Food-Poisoning Microbes from Food ( ) - Lab Report Example In our experiment we will test 10g of lettuce for presence of bacteria that presumably caused outbreak of food-poisoning in a local school. Several children have been complaining of diarrhea, abdominal pain and some have started passing blood in their stool. The lettuce was on the menu as a fresh salad 3 days earlier. We will try to conduct microbiological investigation of the bacteria that are present in the lettuce. Then we will identify if there are present any organisms that can cause food born infection. If organisms are found we will try to find the specific group of bacteria. Also we will have to calculate the concentration of these bacteria and made a conclusion if this concentration is sufficient to cause a disease. In order to test for presence for bacteria we will prepare the food sample for examination. The lettuce was placed in Maximum recovery diluent (MRD) which is an isotonic liquid that contains small concentrations of peptone and it is used to maintaining the viability of eventually present organisms in the food. We than placed the lettuce in 90ml of MRD and put it in the stomacher for 30 sec. The stomacher transforms the food sample into homogenous suspension and promotes the releasing the bacteria into the liquid medium (MRD). We than made different dilutions of the suspension (10-1 10-2 10-3 10-4 10-5 and 10-6) and inoculated them on different agar mediums. We used: Nutrition agar that was inoculated with 10-6 dilution of the suspension had 196 colony forming units, and according from the provided guidance, this dilution was used to calculate the colony forming units per gram according to the formula cfu/gram = No. of colonies x 10 x dilution factor. According to the formula the result nutrient agar produced 10140 cfu/gram. The Violet red bile glucose agar (VRBG) that was inoculated with dilution of 10-6