Potency of plant extracts against Penicillium species isolated from different seeds and fruits in Saudi Arabia.

Antifungal activity of extracts of cinnamon (Cinnamomum zeylanicum), Cloves (Syzygium aromaticum), ginger (Zingiber officinale) and turmeric (Curcuma longa) were evaluated in vitro against 17 Penicillium spp. Seed disease and rotten fruit caused by these species cause considerable loss of quality for different agricultural products. Isolates of Penicillium spp. were screened for production of patulin an important serious mycotoxin. About 70.59% of Penicillium spp. produced this toxin in concentrations ranging from 4 to 31 ppb. The response of Penicillium spp. to plant extracts differed according to the plant extract and concentration. Cinnamon extract showed the greatest effect on P. asperosporum, P. aurintogriseum and P. brevicompactum, and cloves extract produced the greatest effect on P. chermesinum and P. duclauxii. Turmeric extract had less effect on P. duclauxii. Cloves extract was the most effective in reducing the growth of Penicillium spp. On the other hand, ginger extract with all concentrations used had less effect against most Penicillium spp in the laboratory. Plant extracts are promising as natural sources of environmentally friendly compounds in laboratory studies.

Biosynthesis of silver nanoparticles using Penicillium verrucosum and analysis of their antifungal activity.

The present study describes the biosynthesis of silver nanoparticles, using the fungus Penicillium verrucosum. The silver nanoparticles were synthesised by reacting silver nitrate (AgNO3) with the cell free filtrates of the fungal culture, and were then characterized by UV-visible spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive, and X-ray diffraction analysis to further evaluate their successful biosynthesis, optical and morphological features (size and shape), and crystallinity. The bioactivity of the synthesized nanoparticles against two phytopathogenic fungi i.e: Fusarium chlamydosporum and Aspergillus flavus was evaluated using nanomaterial seeding media. These biogenic silver nanoparticles were polydisperse in nature, with a size of 10-12 nm. With regard to the antifungal activity, 150 ppm of the nanoparticles suppressed the growth of F. chlamydosporum and A. flavus by about 50%. To the best of our knowledge, this is the first report on the use of P. verrucosum to synthesise silver nanoparticles. The present study demonstrates a novel, simple, and eco-friendly process for the generation of biofunctionally useful biogenic nanoparticles.

Fatty acid production of thraustochytrids from Saudi Arabian mangroves.

This is the first report of thraustochytrids from Saudi Arabia. A total of 108 isolates of thraustochytrid were cultured from Syhat mangroves, Arabian Gulf, Saudi Arabia. Isolated thraustochytrids belonged to five genera: Aplanochytrium, Aurantiochytrium, Schizochytrium, Thraustochytrium and Ulkenia. Cultured thraustochytrids isolated from decaying leaves of Avicennia marina (77 isolates), sediment (15), seawater (10) and decaying thalli of Sargassum (6). Of the 108 isolates, three strains (SY25, SY38 and SY52) were selected based on their high biomass productivity and high percentages of PUFAs. Phylogenetic analyses based on 18S rDNA placed the three strains within the Aurantiochytrium clade with high statistical support. Species of Aurantiochytrium formed six separate clades, the two strains (SY38 and SY52) formed a separate clade that is a sister clade to the one that contains the type species A. limacinum, while SY25 grouped with Aurantiochytrium sp. TA4, that is also isolated from mangroves in Iran, Arabian Gulf. The strains (SY38 and SY52) shared the phylogenetic placement, their morphology and fatty acid profile. The strain SY25 have different shape of sporangia that divide to give zoospores directly, sporogenous cells are surrounded by thick gelatinous sheath and produce high levels of Linoleic and Oleic essential unsaturated fatty acids. The three studied strain produced high levels of Palmitic acid (ranged between 31.1 and 65.3 % of total fatty acids) that can be further optimized for biofuel production.

Saturnispora mangrovi f.a., sp. nov. from Syhat mangrove, Saudi Arabia.

Strain SY-07 was isolated from decaying leaves of Avicennia marina collected from Syhat mangroves, Dammam city, Arabian Gulf, Saudi Arabia. Phylogenetic analyses of three genes [D1/D2 region of the LSU and SSU rRNA genes and internal transcribed spacer (ITS) region] showed that strain SY-07 represents a novel species of the genus Saturnispora distinct from closely related species. Saturnispora mendoncae was the most closely related species with an LSU gene sequence similarity of 89.3 % (58 nucleotide substitutions and four indels out of 578 nt), 97 % similarity for the SSU gene (42 nucleotide substitutions and 10 indels out of 1614 nt) and 88 % similarity for the ITS region (15 nucleotide substitutions and eight indels out of 430 nt). In addition, strain SY-07 differed from S. mendoncae by its ability to assimilate d-galactose (weak), d-xylose (weak), meso-erythritol (delayed), glucono-δ-lactone, citrate (delayed) and ethylamine. S. mendoncae produced persistent asci that contain two to four spherical ascospores and lacked pseudohyphae, while sexual reproduction was not observed in strain SY-07 and extensive and pseudohyphae were present. Strain SY-07 was able to grow at between 25 and 40 °C, while S. mendoncae did not grow at 37 °C. The name Saturnispora mangrovi f.a., sp. nov. is proposed for strain SY-07. The holotype is CBS 15874, with the ex-type culture AUMC 12005. The MycoBank number for Saturnispora mangrovi f.a., sp. nov. is MB 827036.

Characterization and anti-Aspergillus flavus impact of nanoparticles synthesized by Penicillium citrinum.

This work was conducted to evaluate the ability of grape molding fungus; Penicillium citrinum to synthesize silver nanoparticles (Ag NPs). The potency of biosynthesized Ag NPs was checked against the aflatoxigenic Aspergillus flavus var. columnaris, isolated from sorghum grains. Biosynthesized Ag NPs were characterized and confirmed in different ways. X ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS), Transmission Electron Microscopy (TEM) and optical absorption measurements confirmed the bio-synthesis of Ag NPs. The in vitro antifungal investigation showed that biosynthesized Ag NPs were capable of inhibiting the growth of aflatoxigenic A. flavus var. columnaris. Utilization of plant pathogenic fungi in the Ag NPs biosynthesis as well as the use of bio-Ag NPs to control fungal plant diseases instead of chemicals is promising. Further work is needed to confirm the efficacy of the bio-Ag NPs against different mycotoxigenic fungi and to determine the potent applicable doses.

Bioengineered silver nanoparticles using Curvularia pallescens and its fungicidal activity against Cladosporium fulvum.

Microorganisms based biosynthesis of nanomaterials has triggered significant attention, due to their great potential as vast source of the production of biocompatible nanoparticles (NPs). Such biosynthesized functional nanomaterials can be used for various biomedical applications. The present study investigates the green synthesis of silver nanoparticles (Ag NPs) using the fungus Curvularia pallescens (C. pallescens) which is isolated from cereals. The C. pallescens cell filtrate was used for the reduction of AgNO3 to Ag NPs. To the best of our knowledge C. pallescens is utilized first time for the preparation of Ag NPs. Several alkaloids and proteins present in the phytopathogenic fungus C. pallescens were mainly responsible for the formation of highly crystalline Ag NPs. The as-synthesized Ag NPs were characterized by using UV-Visible spectroscopy, X-ray diffraction and transmission electron microscopy (TEM). The TEM micrographs have revealed that spherical shaped Ag NPs with polydisperse in size were obtained. These results have clearly suggested that the biomolecules secreted by C. pallescens are mainly responsible for the formation and stabilization of nanoparticles. Furthermore, the antifungal activity of the as-prepared Ag NPs was tested against Cladosporium fulvum, which is the major cause of a serious plant disease, known as tomato leaf mold. The synthesized Ag NPs displayed excellent fungicidal activity against the tested fungal pathogen. The extreme zone of reduction occurred at 50 µL, whereas, an increase in the reduction activity is observed with increasing the concentration of Ag NPs. These encouraging results can be further exploited by employing the as synthesized Ag NPs against various pathogenic fungi in order to ascertain their spectrum of fungicidal activity.

Asymmetric top rotors in electric fields: influence of chaos and collisions in molecular beam deflection experiments.

We report on electric deflection experiments of structural isomers of aminobenzonitrile. They are used as models to study the influence of the asymmetry of a molecule on the molecule-electric field interaction. Experimental deflection profiles are compared to Stark effect calculations. We found increasing deviations from the calculated Stark effect behavior with increasing asymmetry. This deviation is induced by interactions with other particles and is directly related to the chaotic behavior of the rotational motion of asymmetric rotors in a static electric field.