Quantitative determination of nitrogen cycling functional genes in an aquaponic systemJamšek, Jena (Avtor) Griessler Bulc, Tjaša (Mentor) Smits, T. (Komentor) Schmautz, Zala (Komentor) Ovca, Andrej (Recenzent) master's thesessanitary engineeringaquaponicsnitrogen cyclegene abundance16S rRNA genequantitative PCRNitrogen is one of the main nutrients required for the maintenance of the dynamic equilibrium between fish, plants and microorganisms in an aquaponic system. Integrating hydroponic plant production and recirculating aquaculture technology promises to enhance nitrogen use efficiency and overall environmental sustainability. The present study was carried out to quantify nitrogen functional genes involved in the nitrogen cycle by hydroponic lettuce integrated with tilapia aquaculture. We sampled different compartments of the aquaponic system, including biofilter, fish tank, hydroponic sump, hydroponic table, fish feces, fresh sludge, digested sludge and roots. The abundances of nitrogen functional genes were analyzed by comparison to 16S rRNA gene using quantitative polymerase chain reaction affiliated with nitrification and COMAMMOX (bacterial and archaeal amoA, hao, nxrB), denitrification (narG, napA, nirS, nirK, norB, nosZ), DNRA (nrfA), N-fixation (nifH) and ANAMMOX (hzs, hzo). The potential nitrogen cycling genes of bacteria and archaea varied between samples. Targeting these genes revealed high diversity and dominance of bacterial communities. Based on correlation analysis, nitrification was best explained by bacterial and archaeal amoA gene abundance followed by NH4+-N content, whereas denitrification was best explained directly by nirS, nirK, nosZ and norB abundances and NO3--N. Overall, identified functional genes involved in the nitrogen cycle could explain beneficial N processes linking with the microbial communities and operating parameters involved in aquaponics, but a deeper analysis would be required to predict environmental contamination and maintain a functioning aquaponic system.[J. Jamšek]20202020-09-13 07:46:27Magistrsko delo/naloga119933sl