Copper/Carbon Core/Shell Nanoparticles: A Potential Material to Control the Fish Pathogen Saprolegnia parasitica.

Jv Zhang,Liqing Huang,Omid Nekouei,Brett Mackinnon,Sophie St-Hilaire,Hong Liu,Peng Jia,Pok Ng,Ying Yang,Na Li,Jinjin Wang,Juncai Chen,Qianjun Huang

doi:10.3389/fvets.2021.689085

Abstract

Copper-based fungicides have a long history of usage in agriculture and aquaculture. With the rapid development of metal-based nanoparticles, copper-based nanoparticles have attracted attention as a potential material for prevention and control of Saprolegnia parasitica. The present study investigated the effectiveness of copper/carbon core/shell nanoparticles (CCCSNs) and a commercial CCCSNs filter product (COPPERWARE®) against S. parasitica in a recirculating system. Results showed that the growth of agar plugs with mycelium was significantly suppressed after exposure to both CCCSNs powder and COPPERWARE® filters. Even the lowest concentration of CCCSNs used in our study (i.e., 100 mg/mL) exhibited significant inhibitory effects on S. parasitica. The smallest quantity of the filter product COPPERWARE® (3.75 × 3.7 × 1.2 cm, 2.58 g) used in our aquarium study also demonstrated significant inhibition compared with the control group. However, we observed leaching of copper into the water especially when larger quantities of COPPERWARE® were used. Water turbidity issues were also observed in tanks with the filter material. Besides these issues, which should be further investigated if the product is to be used on aquatic species sensitive to copper, CCCSNs has promising potential for water disinfection.

Highlights

Saprolegniasis is one of the most prevalent oomycete diseases in aquaculture [1], and among the Saprolegnia species, Saprolegnia parasitica is an important pathogen of finfish [2]
copper/carbon core/shell nanoparticles (CCCSNs) were added to potato dextrose agar (PDA) while it was in liquid form and sonicated (100 W, 40 kHz) for 30 min under 60◦C to increase the dispersion of the nanoparticles [46]
COPPERWARE R inhibited the growth of S. parasitica in aquarium water regardless of the quantity of material used in our filters (Figure 3 and Supplementary Figure 2)

Summary

Introduction

Saprolegniasis is one of the most prevalent oomycete diseases in aquaculture [1], and among the Saprolegnia species, Saprolegnia parasitica is an important pathogen of finfish [2]. Formalin treatments are forbidden in some countries [6] and more jurisdictions are expected to follow [7] Several other treatments such as salt [8], bronopol [9], and ozone [10] have been reported to be somewhat effective against Saprolegnia spp. Bronopol is effective against saprolegniosis [7], but tolerance to this product has been reported [12] Powerful oxidants such as ozone and hydrogen peroxide can reduce Saprolegnia spp., but these may damage the gills of fish [13, 14]. Despite numerous attempts to find safer, more effective, and environmentally friendly alternatives to malachite green, the solution to controlling saprolegniasis is still elusive [1, 4]

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Conclusion