BIOL240 Lecture Notes - Lecture 9: Gelidium, Meat Extract, Carbohydrate
Document Summary
Nutrient broth/agar is most commonly used (all purpose/general purpose medium) Selective media -> contains chemical substances which will prevent growth of 1 or more groups of bacteria without inhibiting the growth of the desired one. Differential media -> contain certain chemicals which permit differentiation between types of bacteria. Nutrient broth consists of beef extract and peptone (partially digested protein) Agar -> complex carbohydrate, galactan, extracted from marine alga (gelidium), melts at 100 c, cools at 43 c. Sterile free of life, plates must be kept sterile. Principle lethal agent in steam sterilization is heat (microorganisms are killed), higher the temp the quicker it is to sterilize. Autoclave sterilize bacteriological media and surgical equipment, increase temp by building up steam pressure thus preventing boiling (temp at 121 c, gauge read between 15-16 psi, for 15-20 mins), further increasing of temp may alter ingredients in media.
