Synthesis and Characterization of AgNPs

Schizosaccharomyces pombe CBS-1042 (ATCC-16979) was ordered from American Type Culture Collection (ATCC). Yeast peptone dextrose (YPD) agar or broth (Solarbio, Cat No.: LA0220 and LA5010, respectively) was used for culturing during the minimum inhibitory concentration (MIC) testing, MA transferring, nucleic acid extraction, and cryopreservation. AgNPs were prepared following a previously described method by Hebeish et al. (2013) (link). Briefly, 5 g of native maize starch was dissolved in 80 ml of distilled water at pH 12 by adding 1.5 g sodium hydroxide and stirred by a digital heating magnetic stirrer (MIULAB, TP-350S). After the starch was completely dissolved, we added 4.72 g AgNO₃ into 20 ml distilled water, and then the silver nitrate solution to the reducing solution drop by drop. The mixture was incubated at 70°C for 1 h with continuously stirring, and cooled to 25°C. The products were rinsed with an equal volume of ethanol by centrifuging at max speed. AgNPs were characterized by following Wu et al. (2022) (link): the absorption spectrum, size, surface traits, and zeta potential of the AgNPs were measured by a UNICO UV-2100 spectrophotometer, a Jeol (JEM-1200EX) transmission electron microscope, a MERLIN Compact-62-24 scanning electron microscope and a Malvern Panalytical™ Zetasizer Nano-ZS90 size analyzer, respectively. Finally, 10 mg/ml stock solutions of AgNPs were made by dissolving 0.4 g of AgNPs into 40 ml of nuclease-free water.