Editorial: Exploring natural extracts as sustainable antibacterial agents against aquaculture pathogens
Year: 2026
Type: editorial
Abstract: Aquaculture has become an essential component of global food production and is expected to play an increasingly important role in meeting the growing demand for aquatic animal protein. However, the intensification of aquaculture production has also increased the occurrence and incidence of infectious diseases, with bacterial pathogens representing a major constraint to animal health, production efficiency, and economic sustainability (Maezono et al. 2025). Antibiotics have traditionally been among the main tools for controlling bacterial diseases, but their intensive and inappropriate use has contributed to the emergence and dissemination of antimicrobial resistance and has raised concerns about environmental contamination and residues in aquaculture products (Schar et al. 2020). These challenges have intensified the search for alternative and sustainable approaches to disease management. Among them, natural extracts and other bioactive compounds derived from plants, algae, fungi, and microorganisms have attracted increasing attention because of their diverse biological activities and potential to act through multiple pathways.The articles included in this Research Topic, "Exploring Natural Extracts as Sustainable Antibacterial Agents Against Aquaculture Pathogens", illustrate the diversity of natural bioactive compounds currently being investigated as tools for sustainable disease management in aquaculture. The contributions encompass compounds and extracts from terrestrial plants, marine macro-and microalgae, fungi, microbial extracellular products, agro-industrial by-products, and formulated mixtures. Together, these studies address different aspects of pathogen control, including direct antibacterial activity, interference with bacterial virulence and biofilm formation, antioxidant and immunomodulatory effects, modulation of host responses, and the development of functional feeds and alternative delivery systems. Importantly, the studies also illustrate the different stages of evidence currently available in this field, ranging from in vitro and ex vivo characterization to dietary interventions and experimental pathogen challenges.Several contributions focused on identifying and characterizing natural extracts with antibacterial, antioxidant, and immunomodulatory properties. Pham Thi et al. ( 2026) investigated a methanolic leaf extract of Annona glabra (AgME) as a dietary intervention against Edwardsiella ictaluri, Aeromonas veronii, and Vibrio parahaemolyticus in basa fish (Pangasius bocourti). The extract showed antibacterial and antioxidant activities in vitro and, when incorporated into the diet, reduced cumulative mortality and supported hematological and histological recovery following bacterial challenge. Interestingly, its overall performance was comparable to or better than that observed with doxycycline under the experimental conditions, highlighting the potential of plant-derived compounds to combine direct antimicrobial activity with host-supportive effects. These findings also reinforce the importance of evaluating natural extracts in vivo, where their biological activity may extend beyond direct effects on bacterial growth.The diversity of natural sources was further explored by Molina-Roque et al. ( 2026), who evaluated nine terrestrial and marine extracts obtained from agro-industrial by-products and low-value marine biomass. The terrestrial extracts derived from pomegranate peel, citrus fruits, and grape seeds generally contained higher levels of phenolic and flavonoid compounds and exhibited stronger antioxidant and antibacterial activities against Vibrio anguillarum, Vibrio harveyi, and Photobacterium damselae subsp. piscicida. In contrast, several marine macro-and microalgal extracts displayed stronger immunomodulatory effects in gilthead seabream (Sparus aurata) head kidney leukocytes. This contrast illustrates that different natural sources may provide distinct, potentially complementary biological functions, an aspect that could be particularly relevant to the design of multifunctional ingredients rather than single-purpose antimicrobial products.The potential of natural bioactives as functional feed ingredients was also investigated in European seabass and European eel. Castro et al. (2026) evaluated three extracts obtained from white grape marc, an agro-industrial by-product generated during winemaking, in diets for European seabass (Dicentrarchus labrax). Although supplementation did not significantly improve survival or growth, some treatments enhanced antioxidant status and protein efficiency, and supplemented fish showed higher absolute survival after V. harveyi challenge. In European eel (Anguilla anguilla), Molina-Sorribes et al. ( 2026) evaluated a phytobiotic formulation consisting of microencapsulated essential oils against Vibrio vulnificus pathovar piscis. The selected formulation increased plasma lysozyme activity and, following experimental challenge, reduced mortality and delayed disease progression. Together, these studies support the potential of dietary supplementation as a preventive strategy while emphasizing the need to identify formulations and doses that provide measurable protection against infection.Beyond their direct antibacterial effects, several studies investigated natural products that interfere with bacterial virulence and infection processes. García-Márquez et al. ( 2025) evaluated extracellular products from Bacillus pumilus strains cultivated in media supplemented with microalgal and cyanobacterial biomass. Most of the extracellular products inhibited biofilm formation by Aeromonas hydrophila and V. anguillarum, while all tested products affected the expression of the aip56 gene in P. damselae subsp. piscicida and modulated genes involved in iron acquisition (hutB, hutD, irp1, irp2). These results highlight the potential of microbial extracellular products as postbiotic agents that can interfere with pathogen behavior rather than relying exclusively on bacterial killing. Such approaches are particularly relevant in the context of antimicrobial resistance, where strategies targeting virulence or colonization may provide complementary alternatives to conventional antibiotics (Ghosh et al. 2019;MacNair et al. 2024).A similar concept was explored by Morariu et al. (2026), who examined an organic acid-based formulation, AuraAqua, against A. hydrophila. Although the formulation exhibited bactericidal activity, sub-inhibitory concentrations also reduced bacterial adhesion, invasion, motility, and biofilm formation, and downregulated several virulence-associated genes. In primary gut cells from shrimp and tilapia, the treatment preserved epithelial barrier integrity and reduced indicators of cellular damage and oxidative stress during infection. Wang et al. ( 2026) further investigated a combination of extracts from Rheum officinale, Scutellaria baicalensis, and Houttuynia cordata, formulated as effervescent tablets to control V. parahaemolyticus. The optimized formulation exhibited strong bactericidal activity and a relatively narrow window for mutant selection, suggesting a potentially reduced risk of resistance. Although further in vivo validation is required for both works, these studies also highlight the importance of formulation and delivery when translating natural compounds into practical disease-control strategies.Host modulation represents another major theme across the contributions. Ponce et al. ( 2026) evaluated a commercial mushroom-derived product containing Pleurotus ostreatus, Lentinula edodes, and fermented Hericium erinaceum mycelium in European seabass. Long-term dietary supplementation modulated markers associated with both innate and adaptive immunity and increased plasma lysozyme, peroxidase, and bactericidal activities. Importantly, the highest inclusion levels were associated with significantly increased survival following P. damselae subsp. piscicida challenge. These results support the use of mushroom-derived compounds as functional feed ingredients that enhance host defense rather than act directly on the pathogen. Similarly, the study by Molina-Roque et al. (2026) demonstrated that marine extracts can stimulate respiratory burst and peroxidase activity in seabream leukocytes, further supporting the potential contribution of natural compounds to host preparedness against infection.The contributions to this Research Topic also highlight the importance of considering sustainability beyond the simple substitution of antibiotics with natural products. The use of grape marc, plant byproducts, and low-value marine biomass illustrates how bioactive compounds can be recovered from otherwise low-value resources, creating opportunities for circular approaches to aquaculture nutrition. At the same time, natural origin does not automatically guarantee sustainable or practical application. Factors such as extract composition, standardization, stability, bioavailability, dosage, production costs, and scalability will ultimately determine whether promising laboratory results can be translated into commercially viable strategies. The review by Monteiro et al. (2026) on functional compounds for disease control in meagre (Argyrosomus regius) emphasizes this challenge. Although numerous nutritional interventions can modulate immune, oxidative, stress-related, or intestinal responses, direct evidence linking these effects to improved disease resistance remains limited, particularly in long-term and commercial-scale studies.Collectively, the studies presented in this Research Topic demonstrate the wide range of possibilities offered by natural bioactive compounds for the sustainable management of bacterial diseases in aquaculture. They show that these compounds can act through multiple, sometimes complementary, mechanisms, including direct antibacterial activity, disruption of virulence and biofilm formation, modulation of host immune and antioxidant responses, and improvement of physiological resilience. At the same time, the diversity of experimental approaches and outcomes highlights the need for a more integrated and systematic evaluation of these strategies. Future research should move beyond the demonstration of antibacterial activity and establish clearer links between chemical composition, mechanism of action, host responses, microbiota, and actual protection against disease. Much attention to standardization, safety, dosage, formulation, and validation under realistic farming conditions will also be essential. Such efforts will determine whether natural extracts can advance Molina-Sorribes C, Sanjuan E, Barriga-Cuartero J, Amaro C and Fouz B (2026) Phytobiotic-enriched diet enhances survival of European eels (Anguilla anguilla) infected with Vibrio vulnificus pathovar piscis. Front. Mar. Sci. 13:1858406. doi: 10.3389/fmars.2026.1858406 Monteiro M, Oliva-Teles A and Díaz-Rosales P (2026) Functional compounds for sustainable control of infectious diseases in meagre (Argyrosomus regius) aquaculture: a review. Front. Mar. Sci. Ponce M, Zuasti E, Piñeiro A, Alarcón-López FJ and Hachero-Cruzado I (2026) Evaluation of a commercial mushroom-derived product as a dietary immunomodulator and its effects on disease resistance in European seabass (Dicentrarchus labrax) juveniles. Front. Mar. Sci. 13:1970753. doi: 10.3389/fmars.2026.1970753 Schar D, Klein EY, Laxminarayan R, Gilbert M, and Van Boeckel TP (2020) Global trends in antimicrobial use in aquaculture. Sci Rep 10(1):21878. doi: 10.1038/s41598-020-78849-3Wang N, Wu Z, Liu S, Xu Z, Jiang H and Wang H (2026) Rheum, Scutellaria, and Houttuynia effervescent tablets: a green strategy for controlling Vibrio parahaemolyticus outbreaks in aquaculture. Front. Mar. Sci. 13:1895903. doi: 10.3389/fmars.2026.1895903
Source: Frontiers in Marine Science
Language: English
Subfield: Immunology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,801
OpenAlex ID: W7223680964