ORIGINAL ARTICLE Green synthesis of selenium nanoparticles and evaluate their effect on the expression of ERG3, ERG11 and FKS1 antifungal resistance genes in Candida albicans and Candida glabrata M. Hosseini Bafghi 1,2 , H. Zarrinfar 3 , M. Darroudi 4 , M. Zargar 2 and R. Nazari 2 1 Department of Laboratory Sciences, Faculty of Paramedical, Mashhad University of Medical Sciences, Mashhad, Iran 2 Department of Microbiology, Faculty of Science, Qom Branch, Islamic Azad University, Qom, Iran 3 Allergy Research Center, Mashhad University of Medical Sciences, Mashhad, Iran 4 Nuclear Medicine Research Center, Mashhad University of Medical Sciences, Mashhad, Iran Significance and Impact of the Study: Today, the problems of drug resistance have been observed in opportunistic fungi, including various species of Candida. This study investigates the impact of bio- synthesized selenium nanoparticles (Se-NPs) on the growth of standard strains of drug-resistant Candida based on antifungal susceptibility testing and its molecular mechanism. Mutations in antifungal resis- tance target genes have made these strains resistant to common antifungals. Showed that reduced the minimum inhibitory concentration of samples treated with Se-NPs compared with antifungal drugs. Subsequently, the real-time PCR test determined that the expression of target genes was down- regulated in the presence of nanoparticles. Keywords antifungal resistance genes, biosynthesis, Candida, MIC, selenium nanoparticles. Correspondence Razieh Nazari, Department of Microbiology, Faculty of Science, Qom Branch, Islamic Azad University, Qom, Iran. E-mail: Nazari1102002@yahoo.com 2021/0407: received 8 December 2021, revised 30 January 2022 and accepted 1 February 2022 doi:10.1111/lam.13667 Abstract Drug resistance in Candida species has been considerably increased in the last decades. Given the opposition to antifungal agents, toxicity and interactions of the antimicrobial drugs, identifying new antifungal agents seems essential. This study assessed the antifungal effects of nanoparticles (NPs) on the standard strains of Candida albicans and Candida glabrata and determined the expression genes, including ERG3, ERG11 and FKS1. Selenium nanoparticles (Se-NPs) were biosynthesized with a standard strain of C. albicans and approved by several methods including, ultraviolet-visible spectrophotometer, X-ray diffraction technique, Fourier-transform infrared analysis, field-emission scanning electron microscopy and EDX diagram. The antifungal susceptibility testing performed the minimum inhibitory concentrations (MICs) using the CLSI M27-A3 and M27-S4 broth microdilution method. The expression of the desired genes was examined by the real-time PCR assay between untreated and treated by antifungal drugs and Se-NPs. The MICs of itraconazole, amphotericin B and anidulafungin against C. albicans and C. glabrata were 64, 16 and 4 μg ml -1 . In comparison, reduced the MIC values for samples treated with Se-NPs to 1 and 05 μg ml -1 . The results obtained from real-time PCR and analysis of the ΔΔC q values showed that the expression of ERG3, ERG11 and FKS1 genes was significantly down-regulated in Se-NPs concentrations (P <005). This study’s evidence implies biosafety Se-NPs have favourable effects on the reducing expression of ERG3, ERG11 and FKS1 antifungal resistance genes in C. albicans and C. glabrata. Letters in Applied Microbiology 74, 809--819 © 2022 The Society for Applied Microbiology 809 Letters in Applied Microbiology ISSN 0266-8254 Downloaded from https://academic.oup.com/lambio/article/74/5/809/6989224 by guest on 20 January 2023