Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Bacterial Communities Associated with the Cycling of Non-Starch Polysaccharides and Phytate in Aquaponics Systems

Version 1 : Received: 31 October 2021 / Approved: 2 November 2021 / Online: 2 November 2021 (10:12:35 CET)

How to cite: Menezes-Blackburn, D.; Al-Mahrouqi, N.; Al-Siyabi, B.; Al-Kalbani, A.; Greiner, R.; Dobretsov, S. Bacterial Communities Associated with the Cycling of Non-Starch Polysaccharides and Phytate in Aquaponics Systems. Preprints 2021, 2021110031 (doi: 10.20944/preprints202111.0031.v1). Menezes-Blackburn, D.; Al-Mahrouqi, N.; Al-Siyabi, B.; Al-Kalbani, A.; Greiner, R.; Dobretsov, S. Bacterial Communities Associated with the Cycling of Non-Starch Polysaccharides and Phytate in Aquaponics Systems. Preprints 2021, 2021110031 (doi: 10.20944/preprints202111.0031.v1).

Abstract

Aquaponics are efficient systems that associate aquatic organisms’ production and plants by recirculating water and nutrients between aquaculture and hydroponic tanks. In this study, we have characterised the bacterial communities in the fresh water aquaponics system that can mineralise polysaccharides and phytate by producing carbohydrate degrading enzymes and phytases, by 16S rRNA gene sequencing and in vitro culture techniques. Around 20% of the operational taxonomic units (OTUs) identified were previously reported to carry fibre-degrading enzymes putative genes, namely β-glucanase (1%), xylanase (5%) or cellulases (17%). Ten % of the OTUs were previously reported to carry putative genes of phytases with different catalytic mechanisms, namely β-propeller (6%), histidine acid phytases (3%) and protein tyrosine phytase (<1%). Thirty-eight morphologically different bacteria were isolated from biofilms accumulated in fish and plant compartments, and identified to belong to the Bacilli class. Among these, seven could produce xylanase, 8 produced β-glucanase, 14 produced cellulase, and 11 isolates could secrete amylases. In addition, Staphylococcus sp. and Rossellomorea sp. could produce consistent extracellular phytate-degrading activity. The PCR amplification of β-propeller genes both in environmental samples and in the isolates obtained showed that this is the most ecologically relevant phytase type in the aquaponics systems used. In summary, the aquaponics system is abundant with bacteria carrying enzymes responsible for plant-nutrient mineralisation.

Keywords

aquaponics; metabarcoding; bacterial communities; carbohydrases; phytases

Subject

EARTH SCIENCES, Environmental Sciences

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