In this study, we examined dermatophyte infections in patients referred to the Department of Dermatology, EL-Houd El-Marsoud Hospital, Cairo, during March 2004 to June 2005. Of 506 patients enrolled in this investigation, 403 (79.6%) were clinically diagnosed as having dermatophytoses (age range 6-70 years; males 240; females 163). Species identification determined by observation of their macroscopic and microscopic characteristics was complemented with sequencing of the internal transcribed spacer ITS1-5.8S-ITS2 rDNA region. The most common dermatophyte infection diagnosed was tinea capitis (76.4%), followed by tinea corporis (22.3%) and tinea unguium (1.2%). The most frequently isolated dermatophyte species was Trichophyton violaceum, which accounted for most (71.1%) of all the recovered dermatophytes, followed by Microsporum canis (21.09%), Trichophyton rubrum (6.2%), and Microsporum boullardii (0.49%); both Epidermophyton floccosum and Trichophyton tonsurans were each only rarely isolated (0.24%).

An eco-friendly process for the silver nanoparticles (Ag-NPs) biosynthesis was investigated using the fungus Monascus purpureus as a safe and commercially used microorganism. M. purpureus growth filtrate was used for the reduction of the aqueous silver nitrate into Ag-NPs with almost 100% size range of 1-7 nm, which was considered as one of the smallest microbial biosynthesized Ag-NPs. The biosynthesized Ag-NPs were structurally characterized using UV, FTIR, DLS, TEM, and XRD. The biosynthesized Ag-NPs were stable after 3 months with no alteration in shape or size. M. purpureus showed no nitrate reductase activity, whereas its pigments reducing power was decreased after nanoparticles formation indicating its role in the Ag-NPs biosynthesis. The synthesized Ag-NPs exhibited strong antimicrobial activity against different bacteria and yeasts species. The anti-Candida activity of M. purpureus culture filtrate was enhanced in the presence of Ag-NPs; the maximum increase in microbial inhibition was observed against Candida albicans with 1.73 increased folds of inhibition zones, followed by their activity against C. tropicalis and C. glabrata with 0.919- and 0.694-folds of increase, respectively. The obtained results suggest that the biosynthesized Ag-NPs offers a promising cost-effective, eco-friendly, and an alternative way to the conventional method of synthesis that could have wide applications in medicine.

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Cadmium sulphide is one of the most promising materials for solar cells and of great interest due to its useful applications in photonics and electronics, thus the development of bio-mediated synthesis of cadmium sulphide nanoparticles (CdS NPs) is one of the essential areas in nanoparticles. The present study demonstrates for the first time the eco-friendly biosynthesis of CdS NPs using the yeast Trichosporon jirovecii. The biosynthesis of CdS NPs were confirmed by UV-Vis spectrum and characterized by X-ray diffraction assay and electron microscopy. Scanning and transmission electron microscope analyses shows the formation of spherical CdS NPs with a size range of about 6-15 nm with a mean Cd:S molar ratio of 1.0:0.98. T. jirovecii produced hydrogen sulfide on cysteine containing medium confirmed by positive cysteine-desulfhydrase activity and the colony color turned yellow on 0.1 mM cadmium containing medium. T. jirovecii tolerance to cadmium was increased by the UV treatment and three 0.6 mM cadmium tolerant mutants were generated upon the UV radiation treatment. The overall results indicated that T. jirovecii could tolerate cadmium toxicity by its conversion into CdS NPs on cysteine containing medium using cysteine-desulfhydrase as a defense response mechanism.

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The well-known probiotic GRAS Saccharomyces boulardii (CNCM I-745) was used for the rst time to produce glutathione (GSH). The culture conditions affecting GSH biosynthesis were screened using a Plackett-Burman design (PBD). Analyzing the regression coe cients for 12 tested variables; 6 of them, including yeast extract, glucose, peptone and cysteine; temperature and agitation rate had a positive signi cant effect on GSH production with a maximum production of 192 mg/L. The impact of addition time of cysteine was investigated in 19 experiments during the growth time course (0-36 h), the best addition time was 8h post-inoculation producing 235 mg/L of GSH. The most signi cant variables were further explored at 5-levels using Central Composite Rotatable Design (CCRD), giving a maximum production of GSH (552 mg/L). Using ba ed asks, the GSH was increased to 730 mg/L, i.e 1.32-folds increment than obtained using CCRD. The two rate-limiting genes of GSH biosynthesis "γ-glutamyl cysteine synthetase (gsh1) and GSH-synthetase (gsh2) were ampli ed and sequenced to validate the GSH biosynthetic potency of S. boulardii. The sequences of genes showed 99% similarity with gsh1 and gsh2 genes of S. cerevisiae. Glutathione peroxidase was puri ed and characterized from S. boulardii with molecular mass and subunit structure of 80 kDa and 35 kDa as revealed from native and SDS-PAGE, ensuring its homodimeric identity. The activity of GPx was reduced by 2.5-folds upon demetallization con rming its metalloproteinic identity. The enzyme was strongly inhibited by hydroxylamine and DTNB, ensuring the implication of surface lysine and cysteine residues on the enzyme active site domains.

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A new yeast strain with promising probiotic traits was isolated from the Red Sea water samples. The isolate (YMHS) was subjected to genetic characterization and identified as Cryptococcus sp. Nucleotide sequence analysis of the rRNA gene internal transcribed spacer regions showed 95% sequence similarity between the isolate and Cryptococcus albidus. Cryptococcus sp. YMHS exhibited desirable characteristics of probiotic microorganisms; it has tolerance to low pH in simulated gastric juice, resistance to bile salts, hydrophobic characteristics, broad antimicrobial activity, and in vitro ability to degrade cholesterol. The isolate grew well in a semi-defined medium composed of yeast extract, glucose, KHPO, (NH)SO, and MgSO, yielding cell mass of 2.32 and 5.82 g/l in shake flask and in bioreactor cultures, respectively. Fed-batch cultivation, with controlled pH, increased the biomass gradually in culture, reaching 28.5 g/l after 32 h cultivation. Beside the feasible use as a probiotic, the new strain also could be beneficial in the development of functional foods or novel food preservatives. To our knowledge, this is the first report of yeast with probiotic properties isolated from the Red Sea.