The antibacterial activity and immunomodulatory effect of naturally synthesized chitosan and silver nanoparticles against Pseudomonas fluorescence infection in Nile tilapia (Oreochromis niloticus): An in vivo study

Environmental exposure to single and combined ZnO and TiO2 nanoparticles: Implications for rainbow trout gill immune functions and microbiota

ZnO and TiO2 nanoparticles (NPs) are widely employed for their antibacterial properties, but their potential environmental impact is raising concerns. This study aimed to assess their single and combined effects at environmentally relevant concentrations (210 μg L-1) on rainbow trout (Oncorhynchus mykiss) gills microbiota and immune functions. 16S rRNA gene sequencing performed after 5 and 28 days of exposure suggests that TiO2 NPs had a more immediate impact on bacterial diversity, while prolonged exposure to the mixture altered community composition. Changes in the relative abundance of potential pathogenic genera such as Candidatus Piscichlamydia and Flavobacterium were observed. Additionally, while the expression of the pro-inflammatory cytokine il1β, and antibacterial compounds (c3) was downregulated by TiO2 NPs and the mixture, ZnO NPs affected immune (mpo) and tight junction proteins (zo1). These results highlight the differences in the toxicity mechanisms existing between the single NPs and their combination, which showed higher toxicity to the gill bacterial community, but not to immune mechanisms. Furthermore, they suggest that exposure to environmental concentrations of NPs could potentially affect fish mucosal immunity and associated microbiota, highlighting the need for further research on the toxicity of NP mixtures.

Nanotechnology in aquaculture: Transforming the future of food security

In the face of growing global challenges in food security and increasing demand for sustainable protein sources, the aquaculture industry is undergoing a transformative shift through the integration of nanotechnology. This review paper explores the profound role of nanotechnology in aquaculture, addressing critical issues such as efficient feed utilization, disease management, and environmental sustainability. Nanomaterials are used to enhance nutritional content and digestibility of aquafeed, optimize fish growth and health, and improve disease prevention. Nanoparticle-based vaccines and drug delivery systems reduce antibiotic reliance, while nano sensors monitor water quality in real-time. Furthermore, nanotechnology has revolutionized infrastructure design, contributing to smart, self-regulating aquaculture systems. Despite its vast potential, challenges such as ethical considerations and long-term safety must be addressed. This paper highlights nanotechnology's transformative role in aquaculture, underscoring its potential to contribute significantly to global food security through enhanced productivity and sustainability.

Nanotechnology: An avenue for combating fish parasites in aquaculture system

The intensification of aquaculture in recent years has led to the rise of infectious fish diseases caused by bacteria, viruses, and parasites. Parasitic diseases, in particular, are widespread and have significant economic impacts globally. Protozoan parasites like Ichthyophthirius multifiliis and Trichodina sp., myxozoans (cnidarians), monogeneans like Dactylogyrus sp. and Gyrodactylus sp., and crustacean parasites like Argulus sp. and Lernaea cyprinacea primarily cause these diseases. Despite advancements and new technologies aimed at understanding and treating these diseases, parasites remain a major health challenge in aquaculture. Traditional antiparasitic agents face limitations, including drug resistance and negative effects on non-target organisms. Recently, nanotechnology has emerged as a novel approach in aquaculture medicine, enabling the development of effective nanoparticles against pathogenic microbes. Silver nanoparticles (AgNPs) are particularly notable for their strong antimicrobial and antiparasitic properties due to their broad mechanisms of action. Although Argulus is a highly destructive crustacean parasite that financially burdens fish farmers, applying nanoparticles to manage this infection in aquaculture is still underexplored. Therefore, this review explores recent efforts to combat parasitic diseases with AgNPs and investigates their potential parasiticidal mechanisms of action, proposing them as a novel tool that could improve the management and control of argulosis diseases. The article underscores the benefits and challenges of this technology, emphasizing its significance in fostering improved health management for sustainable aquaculture.

In vivo toxicological assessment of silver nanoparticle in edible fish, Oreochromis mossambicus

Silver nanoparticles are the extensively utilized among all nanoparticles due to their antibacterial and wound healing properties making them highly suitable for medical and pharmaceutical applications. The field of nanoparticle toxicity is an emerging field and the present study aims to assess the biochemical, hematological and genotoxicity in Oreochromis mossambicus exposed to different concentrations of silver nanoparticles for 7 and 14 days. Silver nanoparticles were synthesized by reduction of silver nitrate using trisodium citrate and was characterized using X-ray diffraction, SEM, HRTEM and DLS. Hematological parameters like RBC, WBC, Hb, HCT and MCV and for biochemical analysis, antioxidant enzymes SOD, CAT and GPX and serum enzymes AST, ALT, ACP, ALP and LDH were analyzed. Genotoxicity was studied using comet assay. Results obtained showed decrease in erythrocytes, HCT, Hb and MCV while an increase was noted in WBC on day 7 and 14. The antioxidant enzymes SOD, CAT and GPx showed a decrease and the lipid peroxidation product MDA was elevated. The serum enzymes AST, ALT, ACP ALP and LDH showed an increased activity when compared to control. DNA damage was evident by an increase in % TDNA. The results indicate hematological, biochemical and genotoxicity of silver nanoparticles that might be mediated through ROS generation in O. mossambicus.

Chitosan nanoparticles and green synthesized silver nanoparticles as novel alternatives to antibiotics for preventing A.hydrophila subsp. hydrophila infection in Nile tilapia, Oreochromis niloticus

Recently, nanoparticles have attracted attention as a preventive tool for certain infectious diseases affecting fish in aquaculture. Furthermore, freshwater fishes are frequently vulnerable to summer mass morality caused by Aeromonas bacteria. In this regard, we focused on the evaluation of the in vitro and in vivo antimicrobial activity of chitosan (CNPs) and silver (AgNPs) nanoparticles against Aeromonas hydrophila subsp. hydrophila. CNPs and AgNPs were prepared at a mean particle size of 9.03 and 12.8 nm and a charge equalled+36.4 and -19.3 mV for CNPs and AgNPs, respectively. A. hydrophila subsp. hydrophila, Aeromonas caviae, and Aeromonas punctata were retrieved and identified by traditional and molecular techniques. The sensitivity of the obtained bacteria to eight different antibiotic discs was also tested. The antibiotic sensitivity studies revealed the presence of multidrug-resistant (MDR) Aeromonas species (spp.). The bacterium that showed the highest multidrug resistance against the tested antibiotic discs was Aeromonas hydrophila subsp. hydrophila. Therefore, CNPs and AgNPs were in vitro tested against the isolated bacterium and exhibited inhibition zones of 15 and 25 mm, respectively. TEM images also showed that CNPs and AgNPs had an antagonistic action against the same bacterium causing loss of architecture and bacterial death.