Aquaponic Systems for Sustainable Resource Recovery: Linking Nitrogen Transformations to Microbial Communities.

Area of Science:

• Agricultural Science
• Environmental Microbiology
• Aquaculture Engineering

Background:

• Aquaponics integrates aquaculture and hydroponics for food production and waste remediation.
• Improving nitrogen use efficiency (NUE) is critical for sustainable aquaponics.
• Aquaculture effluent contains high nitrogen levels requiring effective management.

Purpose of the Study:

• To investigate bacterial communities and nitrogen transformations in aquaponics.
• To evaluate the impact of pH on nitrogen cycling and NUE.
• To identify strategies for enhancing NUE and water quality in aquaponics.

Main Methods:

• Quantitative polymerase chain reactions (qPCR) and next-generation sequencing (NGS) were used.
• Bacterial communities in plant roots and biofilters were analyzed.
• Nitrogen transformations were assessed across different plant types and pH levels (7.0, 6.0, 5.2).

Main Results:

• Low nitrifier abundance in roots and biofilters indicated nitrogen loss, reducing NUE.
• Low pH significantly altered microbial communities and decreased nitrifier abundance, causing ammonia accumulation.
• Nitrite-oxidizing bacteria (e.g., Nitrospira spp.) abundance in plant roots remained stable at low pH, suggesting plant-mediated nitrification benefits.

Conclusions:

• Plant roots play a beneficial role in nitrification, improving NUE in aquaponics.
• Optimizing pH is crucial for managing microbial communities and nitrogen cycling.
• Understanding microbial dynamics offers strategies to enhance aquaponics performance and nutrient recovery.