1. Agar Plate
Agar is a gelatinous polymer substance derived from red algae and commonly used in a
biological laboratory setting as a substrate.
An agar plate is a Petri dish that contains agar as a solid growth medium plus nutrients,
used to culture microorganisms.
Individual microorganisms placed on the plate will grow into individual colonies, each
a clone genetically identical to the individual ancestor organism.
Plating must be done in a laminar flow cabinet or on the working bench next to a bunsen
burner.
Several methods are available to plate out cells. Some of them are spread plate,
Streaking, spot analysis, use of sterile glass beads and replica plating.
In streaking technique, a drop of the culture on the end of a thin, sterile loop of wire,
sometimes known as inoculators, is streaked across the surface of the agar leaving
organisms behind, a higher number at the beginning of the streak and a lower number at
the end.
Spot analysis is often used to check the viability of cells.
A third used technique is the use of sterile glass beads to plate out cells. In this technique
cells are grown in a liquid culture of which a small volume is pipetted on the agar plate
and then spread out with the beads.
Replica plating is another technique in order to plate out cells on agar plates.
