When bacteria are cultured on solid media, it grows in formations called colonies. A bacterial colony
is a cluster of cells derived from the same mother cell. They are fascinating microcosms that can reveal a wealth of information about the microorganisms that inhabit them.
Microbiologists often use bacterial colonies to study bacterial populations’ growth and behavior, but what can we learn from these colonies?
Read on to explore some of the key insights these colonies can provide, from understanding bacterial physiology to tracking the evolution of antibiotic resistance.
One of the most obvious ways that bacterial colonies can provide insight is through their morphological features. Morphology refers to the visual and physical characteristics of a cultured colony. The shape, size, and color of a colony can all provide important information about the bacteria within it.
The color of a colony gives insight into both species and the metabolic activities of the bacteria within it. Consider the vibrant gold color of staphylococcus aureus that comes from a carotenoid or the plant-like green found in Cyanobacteria from bacteriochlorophyll. Colonial morphology provides the richest information about bacterial colonies. For this reason, colony picking robots use visual images in 2D or 3D to capture information about bacterial colonies. The colony picking robots can be set with specific parameters to choose the right type of colony sample for a given application. Specialized colony picking robots have been designed to pick cells from a bacterial colony and inoculate growth media to segregate colonies grown from a single cell.
Bacterial colonies can also provide insight into bacterial physiology. Colony growth patterns provide insight into how bacteria respond to different environmental conditions. How a colony spreads over the surface of a petri dish can indicate whether the bacteria are motile or not.
Also, studying colonies’ growth rates can provide insight into how bacteria respond to different nutrients and growth conditions.
Studying bacterial colonies can provide clues to antibiotic resistance. Growing a sample on a medium that contains an antibiotic will identify which colonies can survive exposure to that antibiotic. A colony that can grow in the presence of an antibiotic that would normally inhibit its growth has a resistance mutation.
Analyzing the genetic makeup of colonies that have developed resistance can help scientists develop strategies to combat antibiotic resistance.
Cooperation and Communication Patterns
We don’t often think of bacteria as social creatures, but bacteria can communicate between themselves with physical and chemical signals. Bacteria can behave cooperatively or competitively. The chemical signals that bacteria release to communicate are called autoinducers.
Sometimes, bacteria use autoinducers to confuse or trick other bacteria — perhaps to protect a food source. In colonies, bacteria use autoinducers to cooperate and achieve greater outcomes in a group. For example, bacterial colonies will reorganize to maximize nutrient availability when nutrient sources are limited. Observing bacterial colony behavior over time provides further insight into how bacteria communicate.
From shape and size to chemical conversations, bacterial colonies illuminate the fascinating world of bacteria. As imaging and data analysis tools improve, even more discoveries will emerge from studying bacterial colony development. Robotic colony picking equipment can help your lab get the most out of your colony cultures
Contact Hudson Robotics today to learn more about lab equipment to study bacterial colonies.