2018 ASHS Annual Conference

Aquaponics, a growing trend in food production, integrates aquaculture and hydroponics into one system where plants get nutrition from aquaculture wastewater. Bacteria function as biofilter to convert ammonia into nitrite and nitrate plants absorb mineral nutrients from the water, and then purified water is returned to the fish tanks. Aquaponics offer a promising solution for sustainable food production by reducing the usage of water and chemical fertilizers. However, due to the reuse and recycling of waste and waste-derived materials, it is important to appropriately assess and manage potential risks associated with food safety in aquaponics systems. Therefore, the aim of this study was to determine the presence of foodborne pathogens in aquaponics systems. To assess food safety, we collected irrigation water and plant tissues from two different food production systems: aquaponics and hydroponics. Common foodborne illness pathogens (Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enteritidis) of vegetables were analyzed. We collected roots and edible parts of lettuce, basil, and tomato after 30-day production period. Weighing 25 g of plant tissue into 225 ml peptone water buffer, blend or stomach briefly as necessary. A series of inoculum dilutions were prepared and spread onto selective agar plates. Colonies were counted after incubated at 37 ºC for 20 hours. Even though there are more bacteria in water samples in aquaponics than in hydroponics, there were no significance differences in the colony-forming units (CFU) of foodborne illness bacteria in plant tissues. In aquaponics and hydroponics, we observed that bacteria are 99.9% in the water, nearly 0.1% inside the roots, and less than 0.1% in the edible part. Because we didn’t change water in production period and there are many nutrition in the water, bacteria can grow in the water. However, foodborne illness bacteria are hard to be transported in plant tissues, so there are less bacteria in roots and edible parts than in the water. We also found that the CFU of bacteria in tomato roots is 34 times to lettuce roots and 9 times to basil roots, because tomato have longer roots, which provide more space to bacteria growth. Key outcomes are expected to identify the food safety issues in aquaponics systems and to enable future research projects to be targeted for commercial production of concern to fill any knowledge gaps.