A great diversity of EcoFABs can be generated in principle and the components of EcoFAB depend on the questions they are designed to address. Hence modular EcoFAB design is very desirable such that there would be ‘core’ EcoFABs relevant for a particular native ecosystem that could be disseminated between labs and then extended as part of the efforts of individual labs.

3-D printing technologies have the potential to greatly enable the construction of EcoFABs either through direct fabrication or through printing molds used to cast Polydimethylsiloxane (PDMS) or other materials. The chamber enables control of liquid flow through the chamber, spatially defined imaging of the root system, and the ability to sample and add microbes and materials to the root system in a spatially defined manner.

 

The native ecosystem that is serving as the reference system is one of the most critical aspects of the EcoFAB design. We envision a stable source of model soil and microbes and a long-term experimental site for validation of our findings.

It is desirable to use plants that are well characterized, genetically transformable, experimentally tractable and small enough to complete their lifecycle in the confines of a compact EcoFAB. A wide range of plants could be used, including plants of the genera Arabidopsis, Setaria, and Brachypodium, among many others.

 

Bacteria should originate from the field site, either as isolates or intact communities, depending on the experimental goals. These isolates can be used to study binary plant-microbe interactions or to construct synthetic communities, whose phenotypes can be compared to the native, enriched communities. Genetic tools (transposon sequencing, double barcoded shotgun expression library sequencing) can be applied to these isolates to gain a mechanistic understanding of their roles in microbial and plant interactions.

Tractability is a key concern for selecting model arbuscular mycorrhizal fungus (AMF) for inclusion in EcoFAB. For this reason, strong consideration should be given for selection of a model AMF species, such as Rhizophagus irregularis, for which a complete genome exists and spores can be easily obtained from existing AMF culture collections.

Small fauna (e.g. arthropods, annelids, mollusks and nematodes), microbial eukaryotes and protists, RNA and DNA viruses associated with the rhizosphere of plant represent an important addition to EcoFABs in that they play critical roles in soil carbon cycling and other nutrient cycling in the rhizosphere.

Soil is one of the most difficult to control aspects of an EcoFAB design. Field soils are generally unsuitable for controlled experiments.  An important research direction for EcoFABs is the development of synthetic soils. These can be a blend of acid washed quartz sand, defined organic amendments and synthetic clays to match the composition.  Additionally, defined media based on biogeochemical analysis of soils may be used.