Microbial Effects on the Production of Aquaponically Grown Lettuce

Abstract

Abstract:In the study of aquaponics, questions have risen concerning the role of microbiota upon plant growth. This experiment compared unaltered aquaponic nutrient solution at pH 7.0 (treatment A7) with sterilized aquaponic nutrient solution at pH 7.0 (treatment SA7) to quantify effects that live microorganisms had on the growth of lettuce (Lactuca sativa). Baseline comparisons were made to conventional hydroponic conditions using inorganic nutrients at pH 5.8 (treatment H5) or pH 7.0 (treatment H7), which showed a 51% reduction in lettuce fresh weight (FW) growth, indicating a strong negative effect of the higher pH nutrient solution; a similar large difference (38%) occurred for dry weight (DW) comparisons between these two treatments. No difference occurred between the sterilized aquaponic treatment (SA7) and H5 in FW or DW. H5 produced more FW and DW than the non-sterile aquaponic treatment (A7). Responses were not different in FW and DW between the two aquaponic conditions. Reduced FW and DW of A7 compared to H5 may be related to the 50 times higher microbial community living in the A7 treatment water than in H5 at the beginning of each trial. Given that the sterile aquaponic solution SA7 and the H5 hydroponic condition were not different in performance, we concluded that the beneficial effects of the microbial community in the fish recirculating aquaculture system (RAS) occurred before the water was sterilized. An interesting implication of our findings is that an RAS can be decoupled from the hydroponic growing system, since its benefits are not dependent upon continuous recirculation between the plant and fish system and its living biotic community.

Plants Dictate Root Microbial Composition in Hydroponics and Aquaponics

“…Most treatments furthermore clustered together at the class rank ( Figure 5A ), with the notable exception being the mature HNS treatments in cluster II. In a prior investigation into the effect of sterilization in the context of RAS coupling, Wielgosz et al (2017) concluded that the beneficial effects on plant growth from RAS effluent were most likely conferred through microbial exudates, and thus unaffected by the sterilization process itself. While the identity of those exudates remains unknown, our results further support their hypothesis by showing that the community composition is not principally determined by the source water (HNS/BF) or source community (mature/sterilized).…”

“…Recent publications focusing on the diversity of microorganisms in aquaponic systems have given rise to many hypotheses as to how the microbial community may lead to increased performance based on the increased abundance of chelating agents, cofactors, enzymes, or hormones facilitating nutrient bioavailability, either directly or indirectly ( Munguia-Fragozo et al, 2015 ; Rurangwa and Verdegem, 2015 ; Schmautz et al, 2017 ; Sheridan et al, 2017 ; Kasozi et al, 2021 ). While the microbial community is widely recognized as important to the success of aquaponic systems ( Delaide et al, 2016 , 2017 ; Goddek et al, 2016b ; Wielgosz et al, 2017 ; Bartelme et al, 2018 ; Goddek and Vermeulen, 2018 ; Eck et al, 2019 ), it has likewise been suspected as a vector for pathogen proliferation ( Mori and Smith, 2019 ; Kasozi et al, 2021 ).…”

Complementary Nutrients in Decoupled Aquaponics Enhance Basil Performance

“…Few studies have explored the reason why biologically derived plant nutrition enhances performance in aquaponics. Studies suggest the microbial activity in aquaponic solutions could have enhanced performance [20], but plants in sterilized aquaponic solutions have been shown to outperform those in unsterilized solutions [25]. More research on the mechanisms behind this performance enhancement in aquaponics is needed.…”

Improving water management in European catfish recirculating aquaculture systems through catfish-lettuce aquaponics

“…Furthermore, it has also been suggested that the bacterial community from the aquaponics may compromise the nutrient availability by consuming nutrients or by increasing the energetic cost to import them across the root interface (Wielgosz et al, 2017). Goddek et al (2015) stated that aquaponics can match hydroponics when all the parameters are controlled, and the bacterial community is fully mature.…”