Characterization Of Gold Nanoparticles Synthesized By Fungus Mariannaea Sp. HJ

In recent years, the biosynthesis of gold nanoparticles (AuNPs) as a frontier and interdisciplinary research field has received extensive attention, and it has a lot of advantages, such as wide raw material sources, moderate reaction condition and less toxic by-products. Biosynthesized AuNPs contain a variety of biologically active molecules, showing good dispersity, stability, biocompatibility as well as unique physical and chemical properties. Therefore, they have wide prospects of application in many fields, including medical imaging, drug transport, food detection and aerospace. At present, the research of AuNPs biosynthesis is, however, in the initial exploration stage, and there are still many problems to be solved. For example, available biological resources are inadequate, the synthetic reaction rate is low, and the morphology of AuNPs is difficult to control. In addition, the application of AuNPs in pollutants degradation is rarely reported. Therefore, it is necessary to develop novel microbial resources, optimize the synthesis conditions and explore more application fields.In this study, a novel strain named HJ was isolated from activated sludge of the secondary sedimentation tank from Chunliu River wastewater treatment plant (Dalian, China). It was identified as Mariannaea sp. based on 26S rRNA gene sequence analysis with GenBank accession number KJ330204. The strain has been preserved in China General Microbiological Culture Collection Center under accession number CGMCC No.10030.The colony diameter of strain HJ could reach 3.2-3.8 cm cultivated on potato dextrose agar for 7 d with oval or spindle conidia. The suitable growth conditions for strain HJ were temperature 30? and pH 7. When the concentration of metal ions such as Sn2+, Co2+ and Ni2+ were at 0.5 mM, the growth of strain HJ was not inhibited notably. Furthermore, strain HJ could tolerate multiple antibiotics including erythromycin, chloramphenicol and tetracycline.Strain HJ could effectively reduce Au3+ to AuNPs. The optimal conditions for AuNPs synthesis by strain HJ were temperature 30?, pH 7 and initial Au3+concentration 2.0 mM, and the reduction rate of Au3+ could reach 87.1%. Based on the analyses of UV-Vis spectroscopy, transmission electron microscopy and X-ray diffraction, the crystal structure of AuNPs was face-centered cubic, and the particles size was in the range of 5-90 nm with varieties of shapes, such as sphere, diamond, hexagon and triangle. Moreover, the biogenic AuNPs performed excellent catalytic properties using sodium borohydride as the reducing agent. Experiments showed that AuNPs could effectively catalyze the reduction of multiple nitro compounds (e.g.4-nitrophenol,3-nitrophenol,2-nitrophenol) and azo dyes (e.g. acid red B, reactive red K-2BP, weak acid red GRS), highlighting the great application potential in the field of environmental remediation.