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Photodynamic inactivation mediated by TMPyP and potassium iodide: a promising strategy for Vibrio anguillarum control in aquaculture
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Resumo(s)
Vibrio anguillarum is a pathogenic bacterium associated with high mortality rates and economic losses in the aquaculture sector. This bacterium is often found in brine shrimp nauplii, a common live food for fish, making it a notable vector for pathogen transmission. This study aimed to evaluate the potential of antimicrobial photodynamic inactivation (aPDI) as a proof-of concept approach for decontamination and prophylactic control of V. anguillarum infections in aquaculture. To accomplish this, the efficiency of aPDI was assessed in: i) photoinactivating V. anguillarum in seawater; ii) decontaminating brine shrimp nauplii (Artemia franciscana) contaminated with V. anguillarum; and iii) preventing infections in turbot (Scophthalmus maximus L.) pre-challenged with V. anguillarum. These experiments employed the tetracationic photosensitizer 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP; 5.0 μM), combined with the well-known aPDI adjuvant potassium iodide (KI, 10-100 mM), under white light irradiation (100 mW cm–2). For the in vivo assays, treatment conditions were selected through toxicity assays and then applied to brine shrimp nauplii and turbot juveniles artificially contaminated with V. anguillarum. The results showed that aPDI mediated by TMPyP + KI efficiently reduced V. anguillarum concentration in seawater to undetectable levels in less than 10 min. Toxicity assays confirmed that TMPyP (5.0 μM) + KI (10 mM) did not induce detectable adverse effects in turbot and brine shrimp under the tested conditions. This combination also significantly reduced bacterial loads on brine shrimp nauplii (>3 log CFU mL-1) after 30 min. In turbot trials, a 5-min treatment was associated with an attenuation of disease symptoms but did not result in a statistically significant reduction in mortality. Overall, aPDI showed strong potential for reducing V. anguillarum contamination in seawater and live food, supporting its applicability as an environmental decontamination and prophylactic strategy. However, its effectiveness in directly preventing an stablished fish infection appears limited under the tested conditions and may require an earlier or repeated application. Further studies should focus on optimizing timing, dosage, and delivery protocols to improve in vivo protection prophylactic efficacy.
Descrição
Palavras-chave
Antimicrobial Photodynamic Inactivation Fish Seawater Decontamination
Contexto Educativo
Citação
Editora
Elsevier B.V.