Nutrient Agar is used for the cultivation of bacteria and the enumeration of microorganisms in water, wastewater, and other materials. It consists of peptones, beef extract, and agar. This relatively simple composition provides the necessary ingredients for the growth of a large number of microorganisms that are not particularly pathogenic. Peptones are the main source of organic nitrogen, especially amino acids and polypeptides. Beef extract provides water-soluble components such as vitamins, salts, etc. Samples should be inoculated onto the medium as soon as possible after collection, and exposure of samples to air should be minimized. Incubate at 35 – 37 º C for 24-48 hours. Slanted tubes are used for cultures and for maintaining pure cultures. After incubation, most plates will show an area of mixed growth. However, one or more areas will show isolated colonies of the organisms contained in the sample.