Isolation and Identification of Cultivable Bacteria in an Aquaponic System with Koi Carp and Parsley (Petroselinum crispum): Implications for Water Quality and System Health

Abstract

Aquaponic integrates aquaculture and hydroponic plant cultivation into a sustainable food production system. Understand ing the microbial profile, particularly the cultivable bacterial species in such systems, is critical for maintaining the health of both aquatic animals and plants. In this study, water samples were collected from a recirculating aquaponic system containing koi carp (Cyprinus carpio var. koi) and parsley (Petroselinum crispum), as well as from a separate aquaculture tank. Samples were taken from the sump (APS), the fish tank within the aquaponic system (AP FT), and the standalone aquaculture tank (AC). After serial dilutions, the samples were inoculated on Tryptic Soy Agar (TSA) and incubated at 22 °C for 24–48 hours. Isolated colonies were analyzed based on their morphological, physiological, and biochemical characteristics, and further identified using the API 20E system. The bacterial species isolated from the aquaponic system included Bacillus spp., Aeromonas hydrophila, Shewanella putrefaciens, and Flavobacterium spp., Micrococcus luteus, Pseudomonas sp., Serratia spp. In contrast, the aquaculture tank yielded dominantly A. hydrophila, A. caviae, and A. sobria. The absence of A. caviae and A. sobria in the aquaponic system suggests that Bacillus spp. may exert an inhibitory effect against opportunistic pathogens such as A. caviae, and A. sobria. These findings provide valuable insight into the microbial ecology of aquaponic systems and highlight the importance of microbial monitoring for sustainable and healthy production environments. Furthermore, the presence of additional genera such as Pseudomonas, Serratia and Micrococcus highlights the need for broader microbial monitoring beyond typical aquaculture pathogens.

Keywords

• Aquaponic
• cultivable bacteria
• koi carp
• parsley
• water quality
• Bacillus
• Aeromonas

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