Microbial diversity in different compartments of an aquaponics system

Abstract

Aquaponics is a solution for sustainable production of fish and plants in a single semi-closed system, where nutrient-rich water from the aquaculture provides nutrients for plant growth. We examined the microbial communities within an experimental aquaponics system. Whereas the fish feces contained a separate community dominated by bacteria of the genus Cetobacterium, the samples from plant roots, biofilter, and periphyton were more similar to each other, while the communities were more diverse. Detailed examination of the data gave the first indications to functional groups of organisms in the different compartments of the aquaponic system. As other nitrifiers other than members of the genus Nitrospira were only present at low numbers, it was anticipated that Nitrospirae may perform the nitrification process in the biofilm.

Strategic Points in Aquaponics

“…Since microorganisms are ubiquitous, they play an important part in all stages of aquaponic production. The influence of environmental conditions on their abundance, diversity and roles could be investigated, e.g., by further using Novel Generation of Sequencing Methods [26,27]. One of the central questions is appropriate pest and disease control.…”

Potential for Combined Biocontrol Activity against Fungal Fish and Plant Pathogens by Bacterial Isolates from a Model Aquaponic System

“…A recent metagenomics study [23] that studied the same aquaponics unit showed that in the system, only a low amount of lactic acid bacteria was present, however a much larger number of pseudomonads. It also shows that the enrichment step on King's B medium is very effective, as in the fish faeces community sampled during the metagenomics study, only a small number of pseudomonads were present.…”

“…It also shows that the enrichment step on King's B medium is very effective, as in the fish faeces community sampled during the metagenomics study, only a small number of pseudomonads were present. On the other hand, bacteria closely related to or formerly named Pseudomonas were present in large amounts [23].…”

“…The aquaponic system used for collection of samples was situated in a foliar greenhouse (with 270 m 2 area) at Zurich University of Applied Sciences (ZHAW) in Wädenswil (Switzerland) [23]. The system consisted of a recirculating aquaculture unit growing tilapia (in total 3600 L) with a fish tank, drum filter for solids removal, moving bed biofilter, UV filter, and addition of pure oxygen, and a hydroponic section (in total 800 L) using three lines of tomato culture, comparing floating raft culture, nutrient film technique (NFT), and drip irrigation as alternative growing technologies.…”

“…Due to their common traits as members of the taxon Oomycota, we anticipated that the chance of obtaining a single biocontrol agent having an inhibitory effect against both might be higher than when using different pathogens. With the knowledge that aquaponics systems have a broad diversity of bacteria in the different compartments of the system [23], a sampling strategy throughout the system was applied to catch the broadest spectrum of biocontrol agents. Here we report the outcomes of the in vitro screening assays for antagonistic bacteria isolated from the aquaponics system.…”