Silver Armor Against Bacteria: A Battle of Antimicrobial Effectiveness

For many farmers, there is a need to improve crop resistance to pathogenic organisms. Florida’s climate and hurricane-prone location promotes the spread of many crop pathogens making management difficult and expensive. Therefore, this study evaluates using a Do-It-Yourself, DIY, method to produce colloidal silver solutions that may be used as effective inhibitors of bacteria growth. The efficacy was compared across gram-negative and gram-positive bacteria species. Production of colloidal silver used an electric current from eight 9-volt batteries wired in series. The starting silver was a jewelry chain, approx. 98% silver, suspended in a container of distilled water. Treatment effects were compared to a commercially available silver solution (10K, ppm) as the positive control via the Kirby-Baur method. Each petri dish was divided into four quadrants, into which each had a treated cellulose square impregnated with a treatment solution. Treatments were: T1-10K ppm AgNp; T-2-5ppm AgNp, T3-3ppm AgNp; and positive control T4-blank water control. The dimensions of Zones of Clearance (ZOC) and the bacterial growth surrounding treated squares were analyzed. The experiment was replicated four times. Data analysis conducted using one-way ANOVA with post hoc separation of means using the T test and Tukey’s HSD. The positive control solution was the most effective bactericide across all species, followed by Treatment-2 (5-ppm treatment), which caused ZOC in gram-negative species. Treatment-3, the 3ppm, did not significantly affect bacterial suppression, while activity at 5ppm suggests that simple home-based, DIY systems can produce low cost, bactericidal nano-silver solutions. In this experiment the bacterium that tested that is also beneficial to plants, R. rubrum , showed an increased tolerance to all silver treatments. Improving homemade, DIY, systems may provide low-cost treatment solutions against some bacteria species important to backyard agriculturists.