Antimicrobial Activity of Copper and Copper Alloys against Bacteria Pathogens in Processed Canned Fish

Abstract

This research investigated the effects of copper and its alloys on bacterial pathogens in processed canned fish. The research was carried out between January 2024 and August, 2024. Five (5) samples each of canned Fish were obtained from a supermarket in Ogbomoso, Nigeria, and cultured for 24 hours by using Potato Dextrose Agar (PDA), MCconkey Agar (MCA) and Nutrient Agar (NA). The isolates culture was conducted by serial dilution and the bacteria isolates were biochemically characterized for identification. Five hollow cylinders were cast from copper and its alloys at varying compositions of: 100% Cu (A), 90% Cu: 10% Zn (B), 80% Cu: 20% Zn (C), 70% Cu: 30% Zn (D) and 60% Cu: 40% Zn (E). The cultured samples were put in each of the cylinders and the microbial load were recorded for 6 hrs at 2 hrs interval. Scanning Electron Microscopy/Energy Dispersed Spectroscopy (SEM-EDS) was used to capture surface structures of Copper and its alloys with bacteria. Biochemical characterization of bacteria isolates from canned fish showed the presence of Salmonella Aureus, Vibrio Species, Staphylococcus Species and Listeria Species. The microbial colony reduction for fish at 0 hr, 2 hrs, 4 hrs, and 6 hrs for A, B, C, D and E were 150,100, 50 and 0; 150,120, 70 and 10; 150, 130, 76 and 12; 150, 138, 78 and 18; and 150, 142, 86 and 20, respectively. The statistical analysis revealed significant variations in microbial growth inhibition, which were influenced by both the composition of the Cu-Zn mixture and the duration of exposure. For instance, at 100% Cu and 0% Zn, the colony count did not show a statistically significant reduction over time (F = 4.97, P = 0.067). Copper and its alloys have been confirmed to be good antimicrobial agent in controlling the growth of bacteria. Therefore, they can be used as canning in food industries to control microbial growth and prolong shelf life. Characterization results on culture sample on fish, deadly microorganisms like Staphylococcus aureus, is susceptible to grow if canning is defective.