The new strategies that have been developed around fish farming in recent years lie in being able to satisfy world food demand. Thus, little by little the development of biointegrated crops has gained strength, such as aquaponic systems (APS), involving both fish and vegetables in a freshwater recirculation system, supported by a bacterial biofilter with a main function of transforming nitrogenous compounds, this allows a better use of the water and reduces the loss due to replacement of this.
From a more specific point of view, APS is a strategy that presents an important microbial component for its operation, given that the recirculation of water depends on its passage through a bacterial biofilter that is responsible for transforming the ammonia produced by the fish into nitrate, which will serve as an essential nutrient for the growth of plants. Therefore, the objective of this work was to characterize the microbiota associated with the biofilters in the aquaponics systems.
Samples were collected from biofilms associated with biofilters of 1 RAS fish culture system and 2 identical APS located at the Universidad Católica del Norte in the Coquimbo city in Chile. The RAS system and one of the APS maintained 100 fish in culture while the second APS maintained 200 fish in culture. Total DNA extraction was performed with the Quick-DNA Fecal/Soil Microbe Microprep kit from ZYMO research, and the different genomic libraries were generated by amplification of the 16S ribosomal gene using the 16S Barcoding Kit 24 V14 from Oxford Nanopore Technologies. Subsequently, the libraries were sequenced using the Oxford Nanopore Technologies minION sequencer together with the “MinkNOW” software and the “Dorado” software for base calling and barcode demultiplexing. The sequences obtained were analyzed using the SILVAngs platform for identification, and statistical analyses for diversity indices were performed using the R software.
The observed results show low diversity in the biofilters associated with both the aquaponic systems and the RAS system. The cascade biofilter of the RAS system presents a moderate diversity, and the bacteria of the Phyllum Proteobacteria dominate in it. In general, a low number of representatives of the different Phyllum and genera per biofilter is observed, except for the submerged biofilter of the RAS system where cyanobacteria dominate.
ACKNOWLEDGEMENTS
We thank to the Grants “Red Latinoamericana de Biointegración Agro-Acuícola para una Economía Circular Sostenible (SIBIOLAT Plus)” P422RT0090, and “Red Latinoamericana Agro-Acuícola (SIBIOLAT)” FOVI210068, and “Sistemas Biointegrados AgroAcuícolas Sustentables y Sostenibles para Promover Desarrollo y Emprendimiento a Micro, Mediana y Pequeña Escala” FONDEF IT20I0066.