Silver nanoparticles were prepared by chemical reduction. Fusarium graminearum was used as the test strain. To study the inhibition of F. graminearum by silver nanoparticles, we studied the activities of protective enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the contents of osmotic adjustment substances soluble protein, soluble sugar and malonaldehyde (MDA) in F. graminearum. Silver nanoparticles inhibited F. graminearum and the inhibitory effect was increased with the concentration of silver nanoparticles. The inhibition rate of 10 μg/mL silver nanoparticles was more than 90% and EC50 was 0.59 μg/mL. When the treating time prolonged (2, 4, 6, 8 and 10 h), the activity of SOD, CAT and POD increased firstly and then declined. SOD, POD and CAT reached the maximum at 4 hours, and decreased to minimum at 10 hours. Silver nanoparticles also increased the MDA content and reduced the soluble sugar and protein contents in pathogens. These results indicated that cell integrity was destroyed in the presence of silver. This may be one of the inhibiting mechanisms of silver nanoparticles on the growth of F. graminearum.
采用化学还原法制备纳米银，以小麦赤霉病菌为受试菌株，研究纳米银对小麦赤霉病菌抗菌活性、对细胞内3 种保护酶：超氧化物歧化酶 (SOD)、过氧化物酶 (POD)、过氧化氢酶 (CAT) 活性和对细胞渗透调节物质：丙二醛 (MDA)、可溶性蛋白、可溶性糖含量的影响。结果表明：纳米银能显著抑制小麦赤霉病菌的生长，抑制作用随着浓度的增加而不断增大，10 μg/mL 的纳米银对病原菌的抑制率达90%以上，有效中浓度 (EC50)为0.59 μg/mL。随着纳米银处理时间 (2、4、6、8 和10 h) 的增长，3 种酶的活性均出现先增加后降低的变化。SOD、POD 和CAT 均在4 h 出现最高值，10 h 降至最低。纳米银使得菌体内丙二醛含量增加，可溶性蛋白和可溶性糖含量降低。纳米银破坏了病原真菌体内细胞的完整性，这可能是纳米银抑制病原菌生长的机理之一。.
Keywords: Fusarium graminearum; antifungal activity; inhibiting mechanism; silver nanoparticles.