What Is Agar? Agar (sometimes called agar-agar) is a natural, jelly-like substance made from red seaweed. When mixed with hot water and cooled, it forms a firm gel. Because of this unique property, agar has been used for decades in food, science, and environmental testing.
Unlike animal-based gelatin, agar is plant-based, non-toxic, and stable at high temperatures. These qualities make it especially useful in scientific settings where consistency and safety matter.
WHY AGAR MATTERS ENVIRONMENTALLY
Agar’s environmental value starts with where it comes from. Seaweed grows quickly, does not need freshwater, fertilizers, or farmland, and can be harvested sustainably when managed responsibly. This makes agar a renewable, low-impact material compared to many synthetic laboratory products.
Beyond its origins, agar plays an important role in environmental science by helping researchers understand what is happening in water, soil, air, and built environments.
AGAR AS A GROWTH MEDIUM: THE BACKBONE OF MICROBIOLOGY
Agar itself is not a test. Instead, it acts as a growth surface.
In microbiology, the science that studies microscopic life like bacteria and fungi, scientists need a stable place where tiny organisms can grow so they can be seen and identified. Agar provides that surface.
By adding nutrients to agar, researchers create a material that allows microorganisms collected from the environment to grow in a controlled way. This has made agar one of the most important tools in microbiology for over a century.
TRADITIONAL ENVIRONMENTAL & MOLD ANALYSIS: THE AGAR PLATE ERA
For many years, agar was commonly used in mold and environmental sampling.
In traditional mold testing, samples were collected from air, surfaces, or building materials and placed onto agar plates. These plates were then sealed and left to sit for several days. If mold spores were present, they would grow into visible colonies on the agar.
Scientists examined these colonies based on their appearance and used microscopes to identify the type of mold present. This method helped determine whether indoor environments had abnormal mold growth compared to outdoor conditions.
At the time, growing mold on agar plates was one of the most effective tools available for understanding indoor air quality and environmental contamination.
THE SHIFT AWAY FROM CULTURING IN MOLD TESTING
Over time, scientists began to recognize the limitations of growing mold on agar plates.
Not all mold grows well on agar, and some species grow much faster than others, which can skew results. Allowing mold to grow on plates can also exaggerate contamination levels and may not accurately reflect real-world exposure.
In the past, culturing was used because it made mold easier to see and identify with the tools available at the time. Growing mold into visible colonies helped scientists understand what was present when microscopes and imaging techniques were more limited.
Today, improved microscopes and identification methods allow analysts to examine samples directly. Instead of waiting days for mold to grow, samples can be examined under a microscope right away to identify mold spores and fragments. This approach is faster, more representative, and better suited for modern environmental and health-related decision-making.
AGAR’S CONTINUED ROLE IN MICROBIOLOGY & MYCOLOGY
Even though agar is used less often for routine mold testing, it remains essential in science.
In microbiology, agar is still widely used to grow and study bacteria from water, soil, and environmental samples. This helps researchers track pollution, better understand ecosystems, and monitor environmental health.
In mycology — the study of fungi — agar is used to grow fungi and mycelium so scientists can observe how they develop and interact with plants, soil, and nutrients. This research is increasingly important as fungi are explored for roles in soil restoration, waste reduction, and the development of sustainable materials.
While mold testing methods have evolved, agar continues to support controlled studies of microorganisms and fungi that are critical to environmental research and innovation.
BOTTOM LINE
Agar may seem like a basic substance, but its impact on environmental science has been significant. From helping scientists identify mold and bacteria to supporting modern ecological research, agar has enabled a deeper understanding of the microscopic world that shapes our environment.
As interest grows in renewable materials and sustainable science practices, agar stands as a reminder that sometimes simple, nature-derived solutions can support powerful scientific progress.
At Full Spec Environmental, we believe it’s important to understand not just what environmental testing looks like today, but how it has evolved. From early agar-based culturing methods to modern approaches like direct microscopy, each step reflects improvements in accuracy, speed, and real-world relevance. By understanding the tools and methods behind environmental testing, we can make more informed decisions that better protect human health and the environments we work in.