Streaking bacteria on a Petri Plate from -70C frozen culture

Abstract

This protocol describes how to obtain isolated single colonies of any bacterial strain by streak plating, from a -70C frozen stock culture.

Steps

Creating a streak plate

Label bottom of LB agar plate with name, date, E. coli strain, and any additional contents such as antibiotics.

Note

Streak plates from stocks should be replaced weekly and are kept in the blue tray in the small fridge nearest our bench.

Working aseptically, use inoculation loop to take E. coli from the frozen stock by swirling loop on surface of stock until slushy.

Note

Note: Alternatively, a pipette tip can be used to take from E. coli stock and to produce streaks. This will further help to avoid contamination.

Streak loop across one side of the agar plate. Discard loop (if using disposable plastic loop).

Rotate the plate 90°, and starting at the end of the last set of streaks, use a fresh disposable loop (or sterilize the reusable loop) to create streaks on this side of the plate. Working clockwise, repeat with next two sides of the plate, using a fresh loop each time.

Incubate plate at37°C, upside down to prevent condensation.

Abstract

Steps

Creating a streak plate

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