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Image of petri dish for an article entitled, “Your guide to bacterial colonies.”
Published On: January 12th, 2021

A majority of life science research involves culturing and testing microbes, especially bacteria. In culturing these microbial samples, the lab often needs to pick a specific colony and duplicate it.So what is a bacterial colony, and why is it so vital in biological research? A bacterial colony is a mass of bacteria grown from a single mother cell, typically on a solid agar medium.

By culturing a bacterial colony from a single cell, researchers will have reliable, pure material for testing or production of proteins. Read on for more information.

Bacterial Colony Morphology

Describing a bacterial colony’s characteristics is important in any research as it helps with bacteria identification. It also enables you to select the right colony for use in the next stage of a process flow.

Growing a colony for this purpose usually involves spreading a sample of bacteria on a culture plate. You then need to identify bacteria with a colony picking protocol, and that requires you to be familiar with bacterial colony morphology. Different species of bacteria can present other physical characteristics when grown on an agar medium as described below:

  • Form – Describes the basic shape of the colony when viewed from the top—which includes circular, irregular, filamentous, and rhizoid.
  • Elevation – Describes the cross-sectional shape of the colony when viewed from the side. Includes raised, flat, convex, umbonate, crateriform, and pulvinate elevations.
  • Margin – Describes the shape of the edge of the colony when magnified. Common examples include entire (smooth), undulate (wavy), erose (serrated), filamentous, lobate, and curled.
  • Surface – Describes how the surface of the colony looks. Examples include smooth, rough, glistening, dull, rugose, mucoid, viscous, etc.
  • Opacity – Describes the bacterial colony’s opacity, such as opaque, transparent, translucent, and iridescent.
  • Color – Describes the color of the colony, which can be white, red, purple, etc.

Uses of Bacterial Colonies in Life Science

Culturing bacterial samples and selecting a specific colony is used in many applications, including microbiome studies, biofuels research, and more. Since research labs require high throughput and accuracy, many utilize tools like colony picking robots and automated liquid handling machines when processing their samples.

Colony culturing and picking are often part of complex and extensive workflows, making growing and replicating the right bacterial colonies essential. The bacterial colonies produced are often used in colony PCR, protein purification, mass spectrometry, enzymatic assays, and various other processes.

Automation When Working with Bacterial Colonies

Like many laboratory research aspects, the growing and picking of bacterial colonies can be automated with robotics and automation software.

In fact, labs can use automation throughout the workflow, from preparing the bacterial samples for plating to isolating the molecules or proteins of choice from the picked colonies.

A colony picking robot can accurately select the required bacterial colony by using advanced imaging hardware and algorithms. It can determine how many cells are in a colony, on the average from colony size, automatically identify the desired colonies according to customizable parameters such as radius, color, or separation and pick the colonies that fit the preset parameters. It can also automatically record and store information on the selected colonies ensuring you have complete documentation.

Working with bacterial colonies is an essential part of any biological lab as they are often the main component used in research and within the production of proteins and enzymes. Therefore, accurately identifying colony morphology and picking the right colony can significantly improve your lab results.

For more information on bacterial colony picking and colony picking lab equipment, contact Hudson Robotics today.