Enriched Microbial Communities for Ammonium and Nitrite Removal from Recirculating Aquaculture Systems

Abstract

Background: The aim of this study was the enrichment of high-performance microbial communities in biofilters for removal of ammonium and nitrite from aquaculture water. Methods: Ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) were enriched from different environmental water samples. The microbial communities with higher ammonium and nitrite removal activity were selected and adapted to different temperatures [9 ºC, 15 ºC, room temperature (25 ºC), and 30 ºC]. The expression of genes involved in nitrification including ammonia monooxygenase (AMO) and nitrite oxidoreductase (NXR) were measured in temperature-adapted AOB and NOB microbiomes. The microbial species present in the selected microbiomes were identified via 16s rRNA sequencing. Results: The microbial communities containing Nitrosomonas oligotropha and Nitrobacter winogradskyi showed the highest ammonium and nitrite removal activity at all temperatures used for adaptation. Furthermore, the microbial communities do not contain any pathogenic bacteria. They also exhibited the highest expression of AMO and NXR genes. Using the enriched microbial communities, we achieved a 288% and 181% improvement in ammonium and nitrite removal over the commonly used communities in biofilters at 9 °C, respectively. Conclusions: These results suggest that the selected microbiomes allowed for a significant improvement of water quality in a recirculating aquaculture system (RAS).

Lab‐scale data and microbial community structure suggest shortcut nitrogen removal as the predominant nitrogen removal mechanism in post‐aerobic digestion (PAD)

“…Sui et al (2020) evaluated different strategies including a short SRT, to improve nitritation, and were able to achieve a high NAR ratio (81%) along with a selection of AOB at the expense of the NOB that were washed out. The selection of microbial communities to enhance NH 4 + removal has been also reported in other studies (Neissi et al, 2022). Higher NH 4 + performance of Boulder PAD's biomass at full‐scale (McNamara et al, 2022) and in our study can be correlated with higher AOB relative abundance (Figure 5c) and a higher species' richness in PAD's test B biomass (Figure 5a).…”

Ammonia induced toxico‐physiological responses in fish and management interventions

“…217 Apart from chemicals and biofilters, bioaugmentation with the microbial consortium is found to be promising in in situ bioremediation of ammonia in zero water exchange systems like RAS and biofloc technology (BFT) as well as in shrimp culture systems. 195,[218][219][220][221] Although bioaugmentation is a simple, inexpensive and environment friendly method of ammonia mitigation, maintenance of viable bacterial cultures in an active growth phase at a high cell density might be a constraint. 195 Electrooxidation for TAN removal is a recent technology for seawater and freshwater RAS.…”