Fundamentals of Microbiology (2+2)

Spread Plate Technique

For spread plating, agar plates have to be poured and surface-dried in advance. Melt non-selective or general purpose medium by placing the flask of the medium in a water bath. Cool the medium to 45 ° C and pour into petri dishes in such a way that each plate is poured with approximately 20 ml of the medium and allow setting. Dry the surface of the medium either in a 56 ° C incubator or in a laminar flow chamber for 20 min.

Arrange the pre-dried plates in duplicate. Label appropriately. Inoculate 0.1ml each of the 10^-3, 10^-4, 10^-5 and 10-6 dilutions on the surface of the respective plates. Using a sterile bent glass rod, spread the inoculum uniformly well on the surface of each plate. The rod should be sterilized by dipping in alcohol and flaming between spreading operations of each plate. After about 30 min, incubate the plates at 37 ° C or room temperature for 48 h.