Antimicrobial Property of Nanosilver Colloid Prepared by Electrical Spark Discharge Method on Aspergillus niger

This study employed an electrical spark discharge method (ESDM) to prepare a nano-Ag colloid as an antifungal solution. The solution was diluted to two concentrations, and the fungal medium prepared in this study was coated with Aspergillus niger. The nano-Ag colloid solution was mixed with A. niger in various concentrations and dripped onto 3M Petrifilm plates. Inhibited growth observed after several days confirmed the antifungal effect of the nano-Ag colloid on A. niger. Because direct washing produced inaccurate quantitation and yielded A. niger in an excessively high concentration, this study employed an inoculation loop method for A. niger quantitation. The concentrations of A. niger ranged from 10(-2) to 10(-7)%. The optimal colony count was observed on day 2. During an experiment regarding the antifungal effect of the ESDM-prepared nano-Ag colloid on A. niger, 3M Petrifilm plates were employed to observe the growth of A. niger. The colony count of 10(-2)% A. niger without nano-Ag colloid was approximately 60. After the nano-Ag colloid was added, the colony count substantially decreased to approximately 10. The colony count of 10(-7)% A. niger was reduced to 11 or lower after the nano-Ag colloid was added. The results confirmed the antifungal effect of the nano-Ag colloid on the growth of A. niger.