Drivers of microbial community composition in hydroponic leafy green production

May 24, 2023




Soledad Benitez Ponce
Associate Professor – Plant Bacteriology and Agricultural Microbiomes
The Ohio State University
College of Food, Agricultural, and Environmental Sciences Department of Plant Pathology, Wooster, OH, USA


Microorganisms colonize different habitats in agricultural ecosystems, including those under highly controlled environments (i.e. CEA, controlled environment agriculture). As a first step towards the successful management of microorganisms in hydroponic production, a type of CEA, we are characterizing the communities of microorganisms found on various surfaces and production characteristics that influence their establishment.
In hydroponics, plant roots are suspended in a defined nutrient solution, though diverse production practices are used across hydroponic growers. Through on-farm collections and manipulations in research facilities, combined with high throughput sequencing and culturing approaches, we observed that system design (i.e. how the nutrients are delivered to the roots) is the main driver of community composition. Further, the bacterial and fungal communities’ structure differed between habitats (leaves, roots, and nutrient solution) in the hydroponic system, and the type of surface material (i.e. roots, PVC channels, or surface lining) influenced both the buildup of biofilms and the diversity of bacteria recovered from biofilms.
We also observed differences in the abundance of culturable bacteria recovered across production farms with the same system design. Finally, in experimental greenhouses, we observed that nutrient solution management, including EC (electrical conductivity as a measure of nutrient concentration) and source of water, influenced the recovery of culturable bacteria from roots.
Further studies focus on bacterial taxa associated with roots and other surfaces, with emphasis on bacterial genera recovered both through culturing and sequencing efforts.

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