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The use of microorganisms in the synthesis of nanoparticles emerges as an eco-friendly and exciting approach. In this study, silver nanoparticles were successfully synthesized from AgNO 3 by reduction of aqueous Ag ? ions with the cell filtrate of Rhodobacter sphaeroides. Nanoparticles were characterized by means of UV-vis absorption spectroscopy, X-Ray Diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Crystalline nature of the nanoparticles in the fcc structure are confirmed by the peaks in the XRD pattern corresponding to (111), (200), (220) and (311) planes, bright circular spots in the selected are a electron diffraction (SAED) and clear lattice fringes in the high-resolution TEM image. Also, the size of silver nanoparticles was controlled by the specific activity of nitrate reductase in the cell filtrate.

The bioassay-oriented fractionation of mistletoe crude extracts (MCEE) using 75% ethanol and culture products of mistletoe transformed by Rhodobacter sphaeroides, a photosynthetic bacterium (PSBT), revealed that the high cytotoxic activities were due to the petroleum ether extracts (PEs) and the acid-precipitated proteins from the aqueous extracts (AQs) of MCEE and PSBT. The isolated triterpenes may account for the activities of the PEs of MCEE and PSBT, respectively. Extraction of MCEE using petroleum ether led to the isolation of 3-epi-betulinic acid (1), betulonic acid (2), oleanolic acid (3), and beta-amyrin acetate (4), while petroleum ether extraction of PSBT led to the isolation of 1,3,4,betulinic acid (5), erythrodiol (6), and (3beta)-olean-12-ene-3,23-diol (7). The PE of PSBT exerted higher cytotoxicity than the PE of MCEE, which was due to the different triterpene contents of these two extracts. The cytotoxic activities of all compounds were tested, and the results revealed that compounds 1, 2, 3, 5, 6, and 7 contributed significantly to the cytotoxicities of both PEs. The AQ of the PSBT exerted almost the same cytotoxic activity and lower toxicity compared to the AQ of the MCEE. These findings indicate that mistletoe products biotransformed by R. sphaeroides could be used to treat cancers, since they have lower toxicities and higher antitumor activities compared to standard treatments.

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The uniform nanoparticles PbS with diameters about 13 nm could be synthesized by Desulfotomaculum sp. under mild condition. The effects of the processing variables such as pH and temperature were investigated. The obtained products were in detailed by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. The results revealed that the PbS crystallites were identical in structure, shape and size under different temperatures while their morphology changed from rod to spheroidal with pH increasing. In the biological synthetic process for PbS nanoparticles, Desulfotomaculum sp. can use sulfate as a terminal electron acceptor to produce sulfide which acts as the source of sulfur for the formation of PbS nanoparticles. lead sulfide, microbial method, nanoparticles, transmission electron microscopy, X-ray diffraction

Aims: Loranthus tanakae Franch. & Sav is a medicinal plant that has a variety of pharmacological properties. However, its study is currently limited because of its relative shortage of natural abundance. The objective of this work was to find an alternative resource from this plant that could produce its bioactive ingredients. Methods and Results: We isolated endophytic fungi from the twigs of Loranthus tanakae Franch. & Sav and eight flavonoid-producing endophytic fungi were selected. The eight endophytic fungi meeting the criteria were identified as Alternaria tenuissima, Dothiorella gregaria, Penicillium aethiopicum, Nothophoma quercina and Hypoxylon perforatum by morphological and molecular methods. The antioxidant and antibacterial activities of the flavonoid-producing endophytic fungi were investigated in vitro, where Alternaria tenuissima ZP28 and ZM148 demonstrated greater activities than the other six strains. Flavonoids of ZP28 and ZM148 were preliminarily identified by liquid chromatography-mass spectrometry (LC-MS). Conclusion:After screening the flavonoid-producing endophytic fungi, Alternaria tenuissima ZP28 and ZM148 were found to have good antioxidant and antibacterial activities. Overall, this study provided new direction and resources for the acquisition of flavonoids.Significance and impact of the study: Endophytic fungi are a promising alternative approach for the large-scale production of flavonoids from Loranthus tanakae Franch. & Sav.

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