Aspergillus spp. associated with cashew from the regions of Riyadh, Dammam, and Abha were isolated and three different culture media were used to qualitatively measure aflatoxin production by Aspergillus via UV light (365 nm), which was expressed as positive or negative. The obtained data showed that six isolates of A. flavus and four isolates of A. parasiticus were positive for aflatoxin production, while all isolates of A. niger were negative. Five commercially essential oils (thyme, garlic, cinnamon, mint, and rosemary) were tested to determine their influence on growth and aflatoxin production in A. flavus and A. parasiticus by performing high-performance liquid chromatography (HPLC). The results showed that the tested essential oils caused highly significant inhibition of fungal growth and aflatoxin production in A. flavus and A. parasiticus. The extent of the inhibition of fungal growth and aflatoxin production was dependent on the type and concentration of essential oils applied. The results indicate that cinnamon and thyme oils show strong antimicrobial potential. PCR was used with four sets of primer pairs for nor-1, omt-1, ver-1, and aflR genes, enclosed in the aflatoxin biosynthetic pathway. The interpretation of the results revealed that PCR is a rapid and sensitive method.

The use of potent fungal mixed cultures is a promising technique for the biodegradation of crude oil. Four isolates of fungi, namely, Alternaria alternata (AA-1), Aspergillus flavus (AF-3), Aspergillus terreus (AT-7), and Trichoderma harzianum (TH-5), were isolated from date palm soil in Saudi Arabia. The mixed fungal of the four isolates have a powerful tool for biodegradation up to 73.6% of crude oil (1%, w/v) in 14 days. The fungal consortium no. 15 containing the four isolates (1:1:1:1) performed significantly better as a biodegradation agent than other consortium in a variety of environmental factors containing crude oil concentration, incubation temperature, initial pH, biodegradation time and the salinity of the medium. The fungal consortium showed better performance in the biodegradation of normal alkanes (n-alkanes) than that of the polycyclic aromatic hydrocarbons (PAHs); the biodegradation efficiency of normal alkanes of the fungal consortium (67.1%) was clearly high than that of the PAHs (56.8%).

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Metallic gold nanoparticles (AuNPs) were prepared and stabilised with henna (Lawsonia inermis) extract. The synthesis of AuNPs was characterised by ultraviolet-visible (UV-Vis) spectrophotometry, transmission electron microscopy (TEM), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), dynamic light scattering and Fourier-transform infrared spectroscopy (FTIR). This study also investigated the degradation of dichlorodiphenyltrichloroethane (DDT) using AuNPs. The initial concentration of DDT was either 10 or 20 mg/L. In our study, the highest percentage of DDT degradation was obtained when the initial DDT concentration was 20 mg/L. It reached a maximum of 64.1% at 10 mg/L and 77.4% at 20 mg/L after 72 h. DDT degradation was determined using UV-Vis spectrophotometry, FTIR and gas chromatography-mass spectrometry (GC/MS). The GC/MS spectra displayed five peaks related to the DDT degradation products: DDT, dichlorodiphenyldichloroethene (DDE), dichlorodiphenyldichloroethane (DDD), dichlorodiphenylmethane (DDM) and dichlorophenylethane (DCE). Our results indicate that AuNPs had high degradation rates for DDT, which implies that they have potential applications as metal nanoparticles for environmental clean-up.

Five species of Penicillium (Penicillium chrysogenum, P. funiculosum, P. griseofulvum, P. implicatum and P. oxalicum) are implicated in seed-borne diseases. Here, we report the discovery of molecular markers based on the internal transcribed spacer regions of fungal ribosomal DNA (rDNA), which are described as primary DNA barcode markers of fungi, for rapid diagnosis and early detection of Penicillium spp. The present markers are expected to be useful for the prevention of seedling and systemic plant diseases associated with Penicillium spp. Our findings, which provide valuable insights into the taxonomy of Penicillium spp., should contribute to improve safety of agricultural produce, thereby protecting both humans and animals from harmful food contaminants such as mycotoxins. In addition, we examined the cellular fatty acid composition of five species of Penicillium. The species studied were found to possess similar fatty acid composition; however, they differed in terms of relative concentration. The principal fatty acids were oleic acid (C18:1) and linoleic acid (C18:2), comprising 80% or more of the total fatty acid composition of these species. These fatty acid profiles may be useful for characterization and identification of fungi. Data derived from the present study highlight the importance of using polyphasic methods for accurate specieslevel identification of Penicillium.

ABSTRACT. Fermentation is an important industrial process for microbial metabolite development and has wide applications in various fields. Aspergillus is the most important genus of fungi used for the production of microbial enzymes such as cellulase. The Aspergillus genome encodes various cellulolytic enzymes. In this study, we assayed the gene expression and cellulolytic enzyme production of three isolates: A. niger (KSU009), A. terreus (KC462061), and A. flavus (KSU014). Two fermentation systems, submerged fermentation and biofilm fermentation (BF), were used for this purpose. Gene expression analysis by RT-PCR showed that cbhB, exo, eglA, eglB, eglC, and β-actin genes were differentially expressed in the two fermentation systems for these three isolates during enzyme production. Furthermore, the expression of all genes was found to be higher in the BF system. The six genes were not expressed in the isolates with no cellulolytic enzyme production. The isolates were identified by morphological and molecular methods, which were based on macroscopic characteristics and sequence analysis of ITS1, ITS2, and the 5.8S regions of rDNA.

The efficacy of four concentrations of aqueous extracts of 11 local plants in the management of Aspergillus flavus and aflatoxin contamination was investigated by measuring the dry weight of A. flavus. The extracts of Allium sativum gave the best results, decreasing the dry weight of the fungus, followed by Aloe vera, whereas 20% Coriandrum sativum extract had no significant effect on the fungal dry weight. Aqueous 20% extracts of the herb Thymus vulgaris and the rhizome of Zingiber officinalis most strongly inhibited aflatoxin production for B1 (79.1%), followed by the leaf extracts of Olea europaea and Eucalyptus globulus (75.0%), although the effect on A. flavus growth was moderate. The herb T. vulgaris and extract of Ocimum basilicum leaf showed the strongest inhibition of B2 (76.2%). Conversely, the leaf extracts of Zizyphus spina and Cassia italica produced only marginal effects on the percentage of inhibition of aflatoxins B1 and B2. No positive correlation was observed between mycelial growth and aflatoxin production in A. flavus.

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