Much of the research on nutrient dynamics in aquaponic (AP) systems has focused on microbial-driven nitrogen transformation and utilization by plants. There is a lack of information on the dynamics of other essential nutrients, such as Phosphorus. This knowledge gap limits the sustainability, productivity, and capacity for crop diversification in AP systems. The microbial community associated with the plant rhizosphere may play a critical role in driving these transformations and utilization pathways in AP systems.
The aim of this study was to determine how temperature influences the microbial community composition of biofilms from AP systems, with special emphasis on organisms that contribute to phosphorus cycling and availability. Three replicated aquaponic systems were utilized, each maintained at a set temperature (22, 25, 28 ℃). Each system fed one Center of Disease Control biofilm reactors (BioSurface Technologies, Montana USA) in a flow through design using a peristaltic pump (Cartridge Pump, Fisher Scientific, New Hampshire USA) at a flow rate of (2.75 gal/min). Aquaponic systems were stocked with Nile tilapia (Oreochromis nilotics) and bell pepper (Capsicum annum) seedlings. Microbial samples from biofilm reactors were collected every seven days for 21 days. DNA was extracted (Zymo Research, Quick-DNA/RNA Plus) and 16S rRNA was sequenced (Mk1C, Oxford Nanopore) to determine the differences in community composition over time. A principal component analysis (PCA) was used to visualize the patterns between temperature and developmental stage and a Bray-Curtis diversity test was used to determine significance.
The PCA showed distinct groupings of microbial communities based on temperature (Figure 1). Results from the Bray-Curtis test showed significance (P-value < 0.05) between all treatments. The results show that there is a significant difference between the compositions of the microbial communities of biofilm at different temperatures and plant development stage.