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Image of petri dish and picking robot for an article about colony picking protocols.
Published On: December 1st, 2020

Picking colonies—whether bacterial or fungal—from agar plates is a core step in culturing isolated, single-strain colonies for life science research.The process of selecting, picking, and inoculating these agar plate colonies is known as a colony picking protocol. Colony picking protocols can slightly vary across labs, but the basic steps are the same in general. Before exploring what those steps are, it’s important to be clear on what those spots on the agar plate (also known as colonies) are.

What is a Bacterial/Fungal Colony?

A colony grown on a solid medium such as agar can include bacteria, yeast or fungi grown from a single mother cell. Labs culture colonies to obtain pure samples of a type of microorganism to be used in a variety of applications—from the production of synthetic enzymes to other forms of protein. A fungal, yeast, or bacterial colony grows to form a mass with specific characteristics, and these characteristics are what we use to identify the type of microorganism that is cultured.

Colony morphology describes the physical characteristics of a bacterial colony and is helpful in selecting a pure colony of the desired bacteria. Key things to observe when picking colonies from agar plates include the form, margin, elevation, surface appearance, opacity, and color of the colonies.

After identifying a colony—whether by eye or under a microscope—you can then proceed to isolate the desired colony.

Colony Picking Protocol: Basic Steps

Colony picking is the process of selecting a colony of pure, single-strain microbes to duplicate them for further use. Colonies isolated in this stage are used in various other processes, including protein purification, mass spectrometry, and PCR, making colony picking an essential step. Below is what a simplified colony picking protocol looks like:

  1. A suitable colony grown on an agar plate is isolated for picking.
  2. The colony is isolated with a colony-picking tool such as a toothpick, inoculation loop, or pipette tip.
  3. It is then inoculated in a solid or liquid cell culture medium where it is incubated overnight to encourage replication.
  4. The colonies produced are then used in other research stages or stored until ready to be replicated again.

Executing Your Colony Picking Protocol Through Automation

Manually picking colonies is a simple, routine task. However, unlike other routine lab processes, it requires a high degree of precision to obtain the best results. With an automated colony picker, labs can significantly increase their productivity as a robot can accurately identify and pick the right colonies much faster than a human could, and eliminates the potential misplacement errors inherent with a repetitive manual task.

A colony picking robot can be programmed to select bacterial colonies according to specific colony morphologies, transfer the colonies to multiple plates/wells in seconds, and accurately record tracking information.

Since an automated colony picker uses advanced image analysis when picking colonies, it can greatly reduce errors in the lab. It also reduces the need for humans to work on colony picking, allowing staff to focus on other tasks or problem-solving activities.

Are you interested in automated colony picking protocols and systems? Contact us and we’ll be in touch with suggestions on what would work best in your laboratory.