Evaluation of the antibacterial activity of pineapple (Ananas comosus) (L.) Merr. industrial waste against common fish and shellfish pathogens

Abstract

Disposal of industrial pineapple (Ananas comosus) wastes is a pressing environmental issue due to pollution risks when accumulated in large quantities. These wastes are susceptible to microbial spoilage, posing serious environmental and health concerns. Therefore, exploring their conversion into valuable products is crucial for effective waste management. In this study, we assessed the antibiotic properties of pineapple processing wastes against prevalent fish pathogens in aquaculture. The wastes underwent various drying methods: sun-drying (SD), oven-drying (OD), and mechanical dehydration (DH). Ethanol extraction was used to isolate bioactive compounds, which were then tested for antibacterial activity at a concentration of 1000 mg/ml using the Agar Well Diffusion technique and Zone of Inhibition (ZOI) assay. Minimum Inhibitory Concentration (MIC) values were determined across six concentrations: 31.25 mg/ml, 62.50 mg/ml, 125 mg/ml, 250 mg/ml, 500 mg/ml, and 1000 mg/ml. Results indicated that all extracts from different drying processes effectively inhibited all tested aquaculture pathogens. DH extracts showed the highest antibacterial activity against Vibrio harveyi and Vibrio parahaemolyticus, with ZOI of 24.67 + 1.25 mm and 21.67 + 0.47 mm, respectively, and a consistent MIC of 250 mg/ml across all pathogens. SD extracts displayed a MIC of 125 mg/ml against Streptococcus agalactiae, while OD extracts showed a MIC of 1000 mg/ml against Edwardsiella tarda, Aeromonas veronii, and S. agalactiae, and 250 mg/ml against both Vibrio species. Comparative analysis with oxytetracycline did not reveal significant differences. These findings suggest that pineapple waste extracts have potential as natural antibacterial agents against common aquaculture pathogens, offering an eco-friendly alternative to commercial antibiotics.