Shrimp aquaculture is a vital industry in Asia, but outbreaks of acute hepatopancreatic necrosis disease (AHPND), caused by Vibrio parahaemolyticus carrying pirABVP toxin genes, have reduced production and caused serious economic losses. Conventional management strategies, often antibiotic-based, face challenges due to bacterial resistance. Green water technology (GWT) has shown potential as an eco-friendly disease mitigation tool, but its effectiveness under brackishwater conditions against AHPND remains underexplored.
This study examined the antimicrobial potential of proposed brackish-green water technology (BGWT) components, namely the microalgae Nannochloropsis oculata and two fish species, Leiopotherapon plumbeus and Sarotherodon melanotheron. The inhibitory activity of N. oculata was assessed using Kirby–Bauer disk diffusion and minimum inhibitory concentration (MIC) assays. Fish mucus extracts were tested for antimicrobial metabolites, and in vivo trials were conducted by co-culturing fish with VPAHPND in brackishwater systems.
Laboratory assays revealed that N. oculata exhibited both bacteriostatic and bactericidal effects against VPAHPND, with an MIC of 1.5 × 108 cells ml-1. Fish mucus evaluation showed that L. plumbeus produced inhibitory metabolites, while S. melanotheron showed no significant effect. In vivo experiment demonstrated that L. plumbeus biomass at 0.7 g L-1 (T2), and 1.4 g L-1 (T3) significantly reduced bacterial concentrations with negative control (T1) with the highest (Figure 1), indicating its active role in pathogen suppression.
The combined findings highlight the potential of N. oculata and L. plumbeus as potential components of BGWT for reducing AHPND-causing V. parahaemolyticus in brackishwater shrimp culture systems. These eco-friendly agents offer a sustainable, non-antibiotic way to improve shrimp health, mitigate losses, and promote resilient aquaculture.