Aeromonas hydrophila is a heterotrophic, gram negative bacterium which is primary or secondary cause of ulcers, fin rot, tail rot, and hemorrhagic septicaemia in fish. The treatments for this infection are only restricted to some antibiotics. So, novel materials are being searched for combating with bacterial infections and the resulting consequences. In this chapter, Ag2O/CuO nanocomposites were synthesized chemically and characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM) and transmission electron microscope (TEM). The antimicrobial activities of Ag2O/CuO nanoparticles (NPs), was checked by both well diffusion and turbidometric (spectrophotometric) method. Synthesized nanoparticles exhibited their antimicrobial efficacy in both the standard inhibitory assays; these results thus provide a scope for further research on the application of Ag2O/CuO nanoparticles as disinfectant and/or antibiotic in the fishery industry.
TopIntroduction
Fish disease is one of the major threats to the sustainable development of aquaculture causing loss of millions of dollars annually. Aeromonas hydrophila is a gram negative bacterium that can grow both in aerobic and anaerobic condition and causes a variety of diseases in both fish and human populations. There are contradicting views on whether the microbe is a primary cause of diseases or an opportunistic one causing diseases to hosts that are immune compromised and stressed (Nielsen et al., 2001). However, this pathogen has been found to cause ulcers, fin rot, tail rot, and hemorrhagic septicemia and epizootic ulcerative syndrome (EUS) in fishes (Austin et al., 1996; Roberts, 1997). The ubiquitous nature of the bacterium in aquatic environments provides significant opportunity for animals, mainly fish and amphibians to contact and ingest organisms (Seshadri et al., 2006). The treatment for the bacterial infection is limited to very few antibiotics like Tetracycline and Remet-30®. Moreover, the bacteria are developing resistance to the available antibiotics because of prolonged use and new compounds for combating bacteria-borne diseases are being searched for.
Nanotechnology is an emerging scientific field and considered to have potential to generate new and innovative materials. Nanotechnology provides the ability to engineer the properties of materials by controlling their size and this has driven research towards a multitude of potential uses for nanomaterials (Saifuddin et al., 2009). Nanoparticles exhibit distinct optical, thermal, chemical and physical properties from that of the bulk material due to their higher surface area to volume ratio.
The synthesis of nanoparticles from metals possesses various biological processes through co-enzymatic systems. The interaction of these nanoparticles with biologically active ligand in the animal system through chelation (Johari et al., 2009). Due to the increase in the outbreak of bacterial diseases in the aquaculture industry and the development of bacterial resistance, new antibacterial agents are required. Silver nanoparticles have proved to be one of the most effective metallic nanoparticles and good antibacterial activity against some bacterial pathogens (Gong et al., 2007) and fish pathogens (Soltani et al., 2009).
At the present time, antibacterial properties of nano metal oxides have found as novel of antimicrobial agent. Also, the majority of scientists have proposed that the nano metal oxide ions, such as silver or copper have useful to controlling of infectious microorganisms (Bustos-Martinez et al., 2006; Lin et al., 1996; Lin et al., 1998; Shaffiey et al., 2015; Shaffiey et al., 2014).
Guogang Ren achieved so widespread experience on the antibacterial effects of nano copper oxides against of Escherichia coli and meticillin-resistant Staphylococcus aureus (Ren et al., 2009). Jayesh et al. (2007) showed that copper nanocrystales have great promise as antimicrobial agent against Escherichia coli, Bacilus subtilis and Staphylococcus aureus. They also, assume that copper nanoparticles could be have greater affinity to surface active groups of Bacilus subtilis, which may be have led to its greater bactericidal effect. However, limited information on the possible antimicrobial activity of CuO and Ag2O nanoparticles are available and the mechanism of action of the copper nanocrystales is not yet fully established but nowadays, we know that the bactericidal effect of metal nanoparticles can be attributed to their small size, photocatalystic of activity and high surface to volume ratio, which allows them to interact closely with microbial membranes and is not merely due to the release of metal ions in solution (Morones et al., 2005).