Nitrogenated compounds biofiltration under alternative bacterium fixation substrates

Intensive fish culture is a practice in aquaculture systems; however, it can produce negative environmental impacts due to the accumulation of organic nitrogen from feeding procedures, but also from fish wasting products. Recirculating aquaculture systems have emerged as one strategy to reduce these impacts, maintaining a healthy environment for fish. These reduce toxicity level through nitrifying biofilters, which use a microbial consortium to convert ammonia into nitrate. The main component of bacterial consortium is comprised by aerobic ammonia‐oxidizing bacteria and aerobic nitrite‐oxidizing bacteria, which are part of the whole nitrification process. These nitrifying bacteria grow in suspension or in fixed form, the latter characterized by a biofilm formation where bacteria adhere to a physical substrate in a self‐produced polymer matrix. The biofilm formation requires tight communication among bacteria to regulate the transcriptional circuits underlying the production of chemical signal molecules (e.g. N‐acetyl‐homoserine lactones) that control biofilm formation. This coordination is known as quorum sensing and can be considered as a mechanism that contributes to the coupling and maintenance of nitrification rate among bacteria by regulating expression levels of relevant genes associated with nitrification process. Therefore, the control of this process is crucial in recirculating aquaculture systems and its incorrect manipulation can produce a detriment of water quality. We here present an overview of the nitrification process in recirculating aquaculture systems. Subsequently, we describe nitrifying biofilters and nitrifying bacteria. Finally, we discuss how quorum sensing controls the efficiency of nitrifying bacteria and potential applications of nitrifying biofilters in intensive aquaculture systems.

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The Addition of Simple Biological Filters of Different Capacity to Semi-Recirculating Fish Rearing System and Its Effects

Lang

2017

Acta Univ. Agric. Silvic. Mendelianae Brun.

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Aquaculture is currently one of the fastest growing food-producing sectors, accounting for around 50 % of the world's food fish production. Limited resources, together with climatic change, have stimulated the search for solutions to support and sustain the production of fish as a source of protein for human consumption. The integration of a biological filtration (BF) into a semi-recirculating fish rearing system can increase its carrying capacity and increase system efficiency compared to its' energy consumption with minimum changes of system composition and minimal costs. Question is the capacity of the BF installed to a system and how it affects water quality. Two different amounts of BF media (surface) added to semi-recirculating rearing system compared with the same system without BF were tested in case of this study. The results have shown that if the BF capacity is insufficient, BF can have negative effects to the quality of water environment. The insufficient amount of BF media caused 4 times reduction of ammonia nitrogen (N-NH4 + ) in system with BF compared to non BF system so it increased the system capacity for feed load 4 times. On the other hand it also increased nitrite nitrogen concentrations permanently more than 5.8 times for BF system compared to non BF system and increased rearing costs because the need of adding chlorides to the system to protect fish from nitrites toxicity. When the BF was dimensioned properly (next year) there were almost no N-NH4 + in a system (0.10 mg.l

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Nitrogenated compounds biofiltration under alternative bacterium fixation substrates

Cited by 4 publications

References 16 publications

Species Diversity and Functional Prediction of Soil Bacterial Communities in Constructed Wetlands with Different Plant Conditions

Species Diversity and Functional Prediction of Soil Bacterial Communities in Constructed Wetlands with Different Plant Conditions

Overview and future perspectives of nitrifying bacteria on biofilters for recirculating aquaculture systems

The Addition of Simple Biological Filters of Different Capacity to Semi-Recirculating Fish Rearing System and Its Effects

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