Physicochemical properties, anticancer and antimicrobial activities of metallic nanoparticles green synthesized by Aspergillus kambarensis.

In the present study, metal and metal oxide nanoparticles were successfully synthesized using Aspergillus kambarensis. UV-Vis spectroscopy showed maximum absorbance of 417 nm for silver (AgNPs), 542 nm for gold (AuNPs), 582 nm for copper (CuNPs) and 367 nm for zinc oxide (ZnONPs) nanoparticles. Fourier transform infrared spectroscopy indicated the presence of various mycochemicals with diverse functional groups in the fungal cell-free filtrate. Transmission electron microscopy revealed mono and poly dispersed particles with an estimate size of 50 nm and different shapes for synthesized manufacture metallic nanoparticles (MNPs. Dynamic light scattering confirmed that MNPs were dispersed in the size range less than 50 nm. Zeta potential analysis showed values of -41.32 mV (AgNPs), -41.26 mV (AuNPs), -34.74 mV (CuNPs) and 33.72 mV (ZnONPs). X-ray diffraction analysis demonstrated crystalline nature for MNPs. All the synthesized MNPs except AuNPs showed strong antifungal and antibacterial activity in disc diffusion assay with growth inhibition zones of 13.1-44.2 mm as well as anticancer activity against HepG-2 cancer cell line with IC50 in the range of 62.01-77.03 µg/ml. Taken together, the results show that biologically active MNPs synthesized by A. kambarensis for the first time could be considered as promising antimicrobial and anticancer agents for biomedical applications.

Unraveling the importance of molecules of natural origin in antifungal drug development through targeting ergosterol biosynthesis pathway.

Over the past decades, the incidence of life-threatening fungal infections has increased dramatically in particular among patients with hampered immune function. Fungal infections cause around 1.5 million deaths annually, superior to malaria and tuberculosis. With respect to high toxicity, narrow spectrum of activity and drug resistance to current antifungals, there is an urgent need to discover novel leads from molecules of natural origin especially those derived from plants and microorganisms for antifungal drug discovery. Among antifungal drugs introduced into the clinic, those affecting ergosterol biosynthesis are still superior to other classes and the vital role of ergosterol in fungal growth and development. This review highlights current knowledge about available antifungal agents and further issues on antifungal drug discovery from compounds of natural origin which affect ergosterol biosynthesis. Special attention is made to the fungal sterol C24-methyltransferase (SMT), a crucial enzyme in ergosterol biosynthesis pathway as a novel target for rational drug design.

Exploration, antifungal and antiaflatoxigenic activity of halophilic bacteria communities from saline soils of Howze-Soltan playa in Iran.

In the present study, halophilic bacteria communities were explored in saline soils of Howze-Soltan playa in Iran with special attention to their biological activity against an aflatoxigenic Aspergillus parasiticus NRRL 2999. Halophilic bacteria were isolated from a total of 20 saline soils using specific culture media and identified by 16S rRNA sequencing in neighbor-joining tree analysis. Antifungal and antiaflatoxigenic activities of the bacteria were screened by a nor-mutant A. parasiticus NRRL 2999 using visual agar plate assay and confirmed by high-performance liquid chromatography. Among a total of 177 halophilic bacteria belonging to 11 genera, 121 isolates (68.3%) inhibited A. parasiticus growth and/or aflatoxin production. The most potent inhibitory bacteria of the genera Bacillus, Paenibacillus and Staphylococcus were distributed in three main phylogenetic clusters as evidenced by 16S rRNA sequence analysis. A. parasiticus growth was inhibited by 0.7-92.7%, while AFB1 and AFG1 productions were suppressed by 15.1-98.9 and 57.0-99.6%, respectively. Taken together, halophilic bacteria identified in this study may be considered as potential sources of novel bioactive metabolites as well as promising candidates to develop new biocontrol agents for managing toxigenic fungi growth and subsequent aflatoxin contamination of food and feed in practice.

Diversity, molecular phylogeny and fingerprint profiles of airborne Aspergillus species using random amplified polymorphic DNA.

In the present study, diversity and phylogenetic relationship of Aspergillus species isolated from Tehran air was studied using random amplified polymorphic DNA (RAPD)-polymerase chain reaction (RAPD-PCR). Thirty-eight Aspergillus isolates belonging to 12 species i.e. A. niger (28.94 %, 11 isolates), A. flavus (18.42 %, 7 isolates), A. tubingensis (13.15 %, 5 isolates), A. japonicus (10.52 %, 4 isolates), A. ochraceus (10.52 %, 4 isolates), and 2.63 %, 1 isolate from each A. nidulans, A. amstelodami, A. oryzae, A. terreus, A. versicolor, A. flavipes and A. fumigatus were obtained by settle plate method which they were distributed in 18 out of 22 sampling sites examined. Fungal DNA was extracted from cultured mycelia of all Aspergillus isolates on Sabouraud Dextrose Agar and used for amplification of gene fragments in RAPD-PCR using 11 primers. RAPD-PCR data was analyzed using UPGMA software. Resulting dendrogram of combined selected primers including PM1, OPW-04, OPW-05, P160, P54, P10 and OPA14 indicated the distribution of 12 Aspergillus species in 8 major clusters. The similarity coefficient of all 38 Aspergillus isolates ranged from 0.02 to 0.40 indicating a wide degree of similarities and differences within and between species. Taken together, our results showed that various Aspergillus species including some important human pathogenic ones exist in the outdoor air of Tehran by different extents in distribution and diversity and suggested inter- and intra-species genetic diversity among Aspergillus species by RAPD-PCR as a rapid, sensitive and reproducible method.

Cold atmospheric plasma inhibits the growth of Candida albicans by affecting ergosterol biosynthesis and suppresses the fungal virulence factors in vitro.

BACKGROUND: The pathogenic yeast Candida albicans is the most common opportunistic fungal pathogen that is responsible for a wide array of infections in susceptible individuals. Despite recent progress in developing novel antifungal drugs which combat Candida-related disorders, this fungus is still a major cause of life-threatening infections all over the world. In the present study, the effect of cold atmospheric plasma (CAP) was evaluated on the growth of C. albicans with special attention to the ability of the CAP-treated fungus for biofilm formation, ergosterol biosynthesis and phospholipase and proteinase secretory production. METHODS: C. albicans cell suspensions were irradiated over time-scales ranging of 90, 120, 150 and 180s under cold atmospheric plasma contained He/O2 (2%). Treated and untreated yeast cells were analyzed for the growth, biofilm formation, ergosterol content, and activities of phospholipase and proteinase. RESULTS: Our results showed that CAP remarkably suppressed the growth of C. albicans by 31-82% at the given times. Likewise, CAP strongly inhibited the ergosterol biosynthesis by the fungus in the range of 40-91%, biofilm formation by 43-57% and the activities of phospholipase and proteinase enzymes by 4-45%, dose-dependently. CONCLUSION: CAP strongly inhibits the growth and virulence factors of C. albicans and thus, it could be a potential candidate to treat Candida-related superficial and cutaneous infections in practice.

Giberella fujikuroi species complex isolated from maize and wheat in Iran: distribution, molecular identification and fumonisin B1 in vitro biosynthesis.

BACKGROUND: Contamination of food and agricultural crops by Fusarium species is a major concern of food spoilage and a potential public health hazard. In the present study, natural contamination of maize and wheat samples from main cultivation areas of Iran by Fusarium species belonging to the Giberella fujikuroi species complex was evaluated, with special attention to the ability of the isolates to produce fumonisin B1 (FB1 ). RESULTS: A total of 55 Fusarium isolates were obtained from 27/32 maize samples (84.4%) and 11/15 wheat samples (73.3%). They were identified as F. verticillioides (47.3%), F. proliferatum (47.3%), F. fujikuroi (1.8%), F. nygamai (1.8%) and F. redolens (1.8%) by sequence analysis of translation elongation factor 1-α (TEF1-α). Twenty-two of 55 Fusarium isolates belonging to F. proliferatum (23.6%), F. verticillioides (14.5%) and F. fujikuroi (1.8%) produced FB1 in the concentration range 230.4-9565.0 µg mL(-1) . The dendrogram resulting from the TEF1-α profile showed that the genotypes were divided into clusters I, II and III, of which cluster III contained only F. redolens, its first report from Iran. CONCLUSION: On the basis of in vitro FB1 biosynthesis of the analyzed strains, the high degree of contamination of maize and wheat with Fusarium strains reported here should be considered as a potential public health threat, because a meaningful number of the isolates were found to produce hazardous levels of carcinogenic FB1 .

Antimicrobial activity and physical characterization of silver nanoparticles green synthesized using nitrate reductase from Fusarium oxysporum.

Nanostructures from natural sources have received major attention due to wide array of biological activities and less toxicity for humans, animals, and the environment. In the present study, silver nanoparticles were successfully synthesized using a fungal nitrate reductase, and their biological activity was assessed against human pathogenic fungi and bacteria. The enzyme was isolated from Fusarium oxysporum IRAN 31C after culturing on malt extract-glucose-yeast extract-peptone (MGYP) medium. The enzyme was purified by a combination of ultrafiltration and ion exchange chromatography on DEAE Sephadex and its molecular weight was estimated by gel filtration on Sephacryl S-300. The purified enzyme had a maximum yield of 50.84 % with a final purification of 70 folds. With a molecular weight of 214 KDa, it is composed of three subunits of 125, 60, and 25 KDa. The purified enzyme was successfully used for synthesis of silver nanoparticles in a way dependent upon NADPH using gelatin as a capping agent. The synthesized silver nanoparticles were characterized by X-ray diffraction, dynamic light scattering spectroscopy, and transmission and scanning electron microscopy. These stable nonaggregating nanoparticles were spherical in shape with an average size of 50 nm and a zeta potential of -34.3. Evaluation of the antimicrobial effects of synthesized nanoparticles by disk diffusion method showed strong growth inhibitory activity against all tested human pathogenic fungi and bacteria as evident from inhibition zones that ranged from 14 to 25 mm. Successful green synthesis of biologically active silver nanoparticles by a nitrate reductase from F. oxysporum in the present work not only reduces laborious downstream steps such as purification of nanoparticle from interfering cellular components, but also provides a constant source of safe biologically-active nanomaterials with potential application in agriculture and medicine.