Lab session 1

Media preparation Media sterilization Use and care of the microscope

Media – nutrients Used to grow microbes Glucose – energy Peptones – breakdown products of protein Good source of nitrogen, amino acids Yeast extract - vitamins

Liquid medium – nutrient broth Large amount of culture Solid medium – nutrient agar Agar – solidifying agent Extracted from red algae Polysaccharide

Granules of agar from a commercial source Add that to nutrient broth Heat the mixture to dissolve granules Solution cools down to 40oC agar becomes a solid

Agar – good solidifying agent Microbes cannot breakdown agar Cannot metabolize No nutritional value Stays a solid even in incubators Study colony morphology Isolate a specific species from a sample

Agar – sterilized in the autoclave Temperature 121oC, pressure 15psi, 15 minutes Heat labile solutions – solutions of enzymes Filtration Microbes stay on the surface of filter Solution free of microbes goes through the filter

Dry sterilization Glassware – pipets Oven – 180oC for 2 hours Chemical sterilization Disinfectant –clean table tops

Microscope Use of oil immersion objective Focusing an object Total magnification Cleaning and storing