Scientists at Abertay University in Dundee, Scotland, are using X-ray Computed Tomography (CT scanning) and 3D printing to create 3D images of the complex structure and interactions within soils.
Professor Wilfred Otten and his team at the university's SIMBIOS Centre says 3D printing technology has allowed them to closely study replicas of the structure of soil to help reveal the functional mysteries it contains.
Otten says that by inserting fungi and bacteria into the pores within the 3D printed soil models, scientists can observe how microorganisms move, find food and interact in their environment.
"Before X Ray CT scanning became available, soil samples were taken back to the lab and studied there," Otten says. "But that's like studying the rubble of a collapsed building. You would never be able to tell what the structure of the building had been before it fell down, how many rooms it had, or how many people lived in or used it, and all the different things the different people used it for. These days we all know about the ways that species interact with each other and their environments above ground, and how sensitive they are to changes in their habitats. What we often forget is that everything above ground relies on the soil it stands on. It plays a major role in food security and the carbon cycle."
Otten says the complexity of soil structures means studying them requires special techniques which are only now available to scientists.
"There are millions of organisms living in just 1 gram of soil," Otten said. "We know that they move around a lot within that environment, and that they interact with each other, but it has always been difficult to study these interactions in the natural environment. So 3D printing is a major breakthrough for us, because we now have the ability to examine the structure of soil up close, to see how big the pore spaces within it are, how they are linked together, and how the bacteria move through them as we watch their progress in the lab."
Team member Dr. Simona Hapca uses statistical modeling, while Dr. Ruth Falconer uses modeling and visualization techniques to reveal the interactions in soil processes such as water flow and microbial community dynamics. It's hoped that the work will develop a predictive and integrated framework for fungal growth in heterogeneous soil environments.
In combining molecular microbiology, microbial ecology and evolution, the team hopes to gain a clear understanding of how the physical and chemical environments determine microbial colonization.
Otten said he and his team use the soil models as theoretical models to help predict how microbes live and survive in 3D structures such as soil. The researchers analyze one species by providing it with simple food sources before they gradually add more complexity until they close in on replicating the environmental conditions below ground. He said CT scanning is used to obtain data which shows them what the pore structure looks like.
According to Otten, the research is aimed at grasping the overall implications of over-use of soil and what impact that use might have in regard to food security and the role of soil structures in climate change.