Optimization and evaluation of the biochemistry, physico-chemistry and microbiology of aquaponics systems

In a country where food security and erratic water resources are of increasing concern, water based agricultural systems may provide a viable alternative to food production. These soilless systems have the potential to be applied at different production levels, from large to small commercial, as well as at a self-sustaining level in peri-urban areas.

In brief, aquaponics is a combination of plant and fish culture, where nutrients excreted by the fish are mineralised through microbial metabolism. The mineralised waste is absorbed and utilised by plants for growth, thereby providing biological filtration of the water, which is returned to the fish tank. Aquaponics is a recirculating system, providing nutrient rich water to the plants, and clean water to the fish. In a mature, optimized system, plant and fish production occur continuously, providing a constant supply of quality produce.

The research investigates crops grown in water-based systems, and whether these systems are able to produce biomass of comparable nutritional quality to traditional soil produced food. A major focus is the investigation of the microbiome of all compartments of the growth systems as they represent the main source of degradation and mineralization of plant nutrients.  Knowledge of the microbial populations in these systems, and how they function under natural fluctuations such as light and temperature, as caused by seasonal variations; this will allow for better management of these growth systems. Current trials include: i. a seasonal assessment of the diversity and shifts of microbial populations in a small commercial aquaponics system, and ii. an investigation of the use of probiotics in an indoor aquaponics system. The microbial populations are correlated to the water quality, mineralization and nutrient availability, as well plant and fish growth and health. 

General approach:

1. The trials include the monitoring of the water quality and available plant nutrients.
2. The trials include an analysis of the bacterial (16S RNA) and fungi (ITS) populations. A molecular study using MiSeq next generation sequencing to obtain a comprehensive data set of the bacterial and fungal populations in the different components of the aquaponics systems is under investigation.
3. HPLC analysis to evaluate the nutritional markers in the plant produce.

Last Modified: Mon, 16 Nov 2020 16:05:16 SAST