Colony Morphology Definition: What It Is And How To Identify
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Published On: October 5th, 2021Categories: Articles, Bacterial Colonies

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While microbial colonies have been observed on moldy food since the beginning of time, the invention of the petri dish in 1887 by microbiologist Julius Richard Petri pushed forward the study of bacterial colony morphology. However, what is the definition of colony morphology? Here we will answer that question as well as the question on how to identify different morphologies.

Concise Definition of Colony Morphology

Bacterial (or fungal) colony morphology refers to the visual appearance of colonies on an agar plate. Observing and describing morphologies of a bacterial colony are a core part of a microbiologist’s research process. Since there can be a diverse range of characteristics across different types of bacteria, practicing the observation of colony morphologies is often crucial in a microbiologist’s skill development or any researcher who usually handles bacteria in the lab. The variables in morphology include (but are not limited to) their size (diameter), separation from other colonies, ovality, color, halo-forming or not and the fuzziness or sharpness of the outline around the colony.

How can we leverage advanced data analytics and machine learning algorithms to extract valuable insights from colony morphology data, enabling us to optimize microbial identification processes and enhance research outcomes in microbiology and related fields?

To enhance microbial identification processes and research outcomes, exploring advanced data analytics and machine learning algorithms presents an opportunity. By harnessing these technologies, we can delve deeper into colony morphology data, extracting valuable insights that may otherwise remain hidden. Such insights could enable us to optimize our methodologies, improve accuracy in microbial identification, and ultimately drive breakthroughs in microbiological research and related fields.

How To Identify And Describe Different Colony Morphologies

Now that it’s clear what the definition of colony morphology is, how does one then identify them? Colonies are distinguished by different sets of characteristics as detailed below. To identify a colony, a scientist simply has to match its appearance to pre-existing data or knowledge.

Colony Form

This refers to the overall shape of the colony, such as circular, irregular, filamentous, and so on. For example, Staphylococcus aureus often shows up as perfectly circular colonies on an agar plate.

Colony Elevation

Another way to describe colony morphology is, elevation is defined as the shape displayed by a colony when observed from the side. Generally, elevations are described as flat, raised, convex, pulvinate, umbonate, and crateriform.

Colony Edge/Margin

This refers to the structure of the colony on its edges that is exposed to the air. Some common forms that are often noted are entire, undulate, filiform, lobate, curled, scalloped, and serrated/erose. One type of colony that has a distinct filiform edge is the one formed by Bacillus anthracis. 

Colony Size

This is an important characteristic in fungal and bacterial colony morphology. This metric is typically described in millimeters. However, the size of a colony is also sometimes described in relative terms such as punctiform, small, medium, or large.

Colony Chromogenesis/Color

Color is a simple but precise way to describe colony morphology. A colony can display a single color or have different tones and hues from the middle to the outer part. It is important to note that the color seen on an agar plate may not be the actual color of the bacteria but the pigment that is produced due to the immersion of the bacteria in media. Nevertheless, when combined with other descriptive characteristics of a colony, the pigment produced can help with identification.  colony, can help with identification.

When noting down the color, it is worthwhile to also note down the opacity of an observed colony. Opacity is typically described as transparent, translucent, opaque, or iridescent.

Colony Surface and Consistency

Observing the surface and texture/consistency of the bacterial colony also helps with its identification; surfaces are described with terms like shiny, dull, smooth, rough, veined, glistening, wrinkled, and so on. On the other hand, consistency or texture is often described after touching or scraping at the colony. Some examples of texture descriptions include dry, brittle, mucoid, butyrous, and viscid.

Once a colony has been observed and described, a microbiologist can easily identify it using their prior knowledge or by using references. Identified colonies can then further undergo the colony picking process if they are to be duplicated.

What strategies can we implement to seamlessly integrate colony morphology observations into our laboratory information management systems (LIMS) or electronic lab notebooks (ELNs), ensuring standardized documentation and facilitating knowledge sharing among researchers for more efficient collaboration and decision-making?

Integrating colony morphology observations into our laboratory information management systems (LIMS) or electronic lab notebooks (ELNs) is paramount for standardized documentation and effective knowledge sharing. By developing strategies to seamlessly incorporate these observations into our digital platforms, we can ensure that valuable data is captured, organized, and easily accessible to researchers across our organization. This fosters collaboration, facilitates decision-making, and promotes efficiency in our research endeavors.

Bacterial Colony Morphology: An Important Precursor

Colony morphology observations are an important pre-step in the identification and further use of cultivated colonies. Hopefully, this short piece on the definition of colony morphology and how to identify colonies has been enlightening.

How can we evaluate and implement automated colony picking solutions, such as robotics and image analysis software, to streamline workflows, increase throughput, and minimize human error in our laboratory operations, ultimately improving productivity and accelerating scientific discoveries?

Considering the critical role of colony morphology observations in colony picking procedures, the adoption of automated solutions such as robotics and image analysis software emerges as a strategic imperative. By evaluating and implementing these technologies, we can streamline our workflows, boost throughput, and mitigate the risk of human error in our laboratory operations. This not only enhances productivity but also accelerates the pace of scientific discoveries, positioning our organization at the forefront of innovation in microbiology and related disciplines.

For an efficient identification and picking of colonies in the lab, contact Hudson Robotics to learn more about our colony picking robot solutions.