M. A. Abdel-Sater

Xylan-decomposing fungi and xylanolytic activity in agricultural and industrial wastes

Abstract Screening of xylan-decomposing filamentous fungi were carried out in two agricultural and one industrial wastes (30 samples each) collected from Qena Governorate (South Valley) using xylan agar medium. Twenty-six species representing 13 genera were identified from rice straw, wheat straw and sugarcane bagasse on the medium used. Aspergillus flavus, A. niger, Penicillium chrysogenum, P. corylophilum, P. funiculosum, P. oxalicum and Trichoderma harzianum were the most prevalent species on the three substrates. Extracellular xylanase production by selected isolates of the current study was characterized during their growth on xylan as a sole carbon source on solid medium. The results revealed that 93.3% of the isolates tested could degrade xylan and the highest activity against xylan was showed by members of Aspergillus, Fusarium, Penicillium and Trichoderma. The optimum conditions for maximum production of xylanase by Trichoderma harzianum were 8 days after incubation at 35°C and maltose and starch were used as carbon sources, NaNO3 and peptone as nitrogen sources and the culture was initially adjusted to pH 6.

Growth and Enzyme Activities of Fungi and Bacteria in Soil Salinized with Sodium Chloride

In soil salinized with different concentrations of sodium chloride, the total counts of soil fungi were significantly decreased during 11 weeks of incubation. Similarly, the total count of bacteria and actinomycetes were severely depressed by increasing salinity level above 5%. Invertase and urease activities were severely decreased as NaCl concentration increase during the incubation. Also, the effect on nitrate reductase was inhibitory with most treatments.

Fungi associated with the Egyptian cotton leafwormSpodoptera littoralis Boisdoval

A total of 28 species representing 15 fungal genera were found to be associated with the all different stages of the Egyptian cotton leafworm,Spodoptera littoralis Boisd., its faeces and the air of the containers where it was reared on Czapek Dox agar medium at 28°C.Aspergillus was the most common genus and was frequently isolated from all substrates.A. flavus was the only fungus associated with all insect stages. At least two well known facultative pathogens were obtained:Beauveria alba andCephaliophora tropica. Nearly all fungi recovered from insect faeces or its environment were also encountered from different insect stages. Forty-two isolates were tested for their abilities for growth on a synthetic medium (nitrogen- and carbon-free) containing partially purified chitin. Most (76.2%) had moderate growth rates.

Harmonic Mitigation, Maximum Power Point Tracking, and Dynamic Performance of Variable-speed Grid-connected Wind Turbine

Abstract This article presents a method for harmonic mitigation and maximum power point tracking for a variable-speed grid-connected 20-kW wind turbine. The wind energy conversion system consists of a permanent magnet synchronous generator driven by variable-speed 20-kW wind turbine. The output of the permanent magnet synchronous generator is connected to a single-switch three-phase boost rectifier to generate DC voltage, which feeds a current-controlled inverter to interface the system with the electric utility. The single-switch three-phase boost rectifier is an active power factor correction technique to maintain the power factor at the permanent magnet synchronous generator side to nearly unity and mitigate the permanent magnet synchronous generator current harmonics. To mitigate inverter output current and voltage harmonics, an LCL filter has been used. A complete analysis of the harmonic content has been done everywhere in the system. The results show that the proposed maximum power point tracking control strategy succeeded to track the maximum wind power irrespective of the wind speed. This strategy in presence of an LCL filter achieved harmonic mitigation at the permanent magnet synchronous generator and inverter output sides. The dynamic response of the wind energy conversion system is tested under a three-phase fault condition. For comparison purposes, an active power filter is designed and checked against the single-switch three-phase boost rectifier for harmonic mitigation at the permanent magnet synchronous generator side.

Maximum power point tracking for variable speed grid connected small wind turbine

This paper presents a method for harmonic mitigation and maximum power point tracking (MPPT) for a variable speed-grid connected 20 kW wind turbine. The wind energy conversion systems consist of permanent magnet synchronous generator (PMSG) driven by variable-speed 20 kW wind turbine. The output of the PMSG is connected to a single switch three-phase boost rectifier to generate DC voltage which feeds a current controlled inverter to interface the system with the electric utility. The single switch three-phase boost rectifier is an active power factor correction technique to maintain the power factor at the PMSG side to nearly unity and mitigate the PMSG current harmonic. To mitigate inverter output current and voltage harmonics, an LCL filter has been used. A complete analysis of the harmonic content has been done everywhere in the system. The results show that the proposed MPPT control strategy succeeded to track the maximum wind power irrespective of the wind speed. This strategy in presence of LCL filter achieved harmonic mitigation at the PMSG and inverter output sides.

Mycoflora and natural occurrence of mycotoxins in tobacco from cigarettes in Egypt

Forty-two species and 4 varieties belonging to 21 genera were collected from 40 tobacco samples on glucose- and cellulose-Czapeks agar at 28 degrees C and 45 degrees C. The most common mesophiles (at 28 degrees C) in tobacco on the two types of media were: Aspergillus flavus, A. flavus var. columnaris, A. fumigatus, A. niger, Penicillium chrysogenum and P. funiculosum. Two samples were heavily contaminated with members of Fusarium (F. moniliforme, F. oxysporum, F. solani). Some fungi were encountered only on plates of cellulose agar as Chaetomium globosum, Stachybotrys atra var. microspora and S. chartarum. At 45 degrees C the most prevalent fungus was A. fumigatus. Truely thermophiles were also collected: Humicola grisea var. thermoidae, Rhizomucor pusillus and Thermoascus aurantiacus. Based on biological assays (brine shrimp larvae (Artemia salina L.) and Bacillus megatherium test) and chemical analysis of chloroform extraction of tobacco (TLC and UV spectrophotometric), four samples (out of 40) had toxicity and four compounds of mycotoxins were detected namely; aflatoxins B1 & B2 (2 samples; 15.5 and 20.7 micrograms/kg), zearalenone (1 sample, 5.5 micrograms) and T-2 toxin (1 sample, 2.8 micrograms). For studying the tracing of aflatoxins in smoking cigarettes, three doses (10, 20 and 50 micrograms) of aflatoxins B1 and B2 (w/w, 1:1) were injected each in ten cigarettes. All extracts of cigarettes smoke proved to be non-toxic and mycotoxins not detected. However, aflatoxins were detected in topping filter (2.8, 3.5 and 8.8 micrograms/the three doses, respectively).

Ecological and enzymatic studies on fungi associated with biscuits in Egypt

Some 43 species and four varieties belonging to nineteen genera were collected from 30 samples of six types of biscuit on 30% sucrose and 1% starch Czapek-Dox agars at 28°C. The most contaminated samples were chocolate wafers with 327 and 195 colonies g−1, 12 and 8 genara and 18 and 13 species on the media, respectively. Samples of wafers without jam and jam wafers were less contaminated with fungi. The most frequently isolated fungi on the two media were Alternaria alternata, Aspergillus alutaceus, A. fumigatus, A. niger, A. sydowii, Cladosporium cladosporioides, C. herbarum, Penicillium chrysogenum, P. janczewskii and yeasts (Saccharomyces spp.). The osmophiles, Eurotium amstelodami and E. repens, were infrequently isolated from chocolates and jam-wafer biscuits. All 69 isolates tested produced invertase and could produce 90%, respectively, amylase, caseinase, and catalase.

Incidence and biodiversity of yeasts, dermatophytes and non-dermatophytes in superficial skin infections in Assiut, Egypt

OBJECTIVE The aim was to identify the incidence of the causal agents from dermatophytes, non-dermatophytes and yeasts in Assiut Governorate employing, beside the morphological and physiological techniques, the genotypic ones. PATIENTS Samples from infected nails, skin and hair were taken from 125 patients. MATERIALS AND METHODS Patients who presented with onychomycosis, tinea capitis, tinea corporis, tinea cruris and tinea pedis during the period from February 2012 to October 2015 were clinically examined and diagnosed by dermatologists and were guided to Assiut University Mycological Centre for direct microscopic examination, culturing and identification. RESULTS Onychomycosis was the most common infecting (64.8% of the cases) followed by tinea capitis (17.6%). Direct microscopic preparations showed only 45 positive cases, while 96 cases showed positive cultures. Infections were more frequent in females than males. Fifty-one fungal species and 1 variety were obtained. Yeasts were the main agents being cultured from 46.02% of total cases. Non-dermatophytes were the second etiologic agents. Aspergillus was responsible for infecting 19.47% of total cases and dermatophytes appeared in only 15.93% of the cases. CONCLUSIONS Yeasts were the main causal agents followed by non-dermatophytic fungi (mainly species of Aspergillus, then Alternaria, Scopulariopsis and Fusarium). Both direct microscopic preparations and culturing are recommended for mycological evaluation of clinical specimens. Sequence analysis of ITS region is recommended for yeast identification.

Effect of Paraquat and Ametryne on soil, root and leaf-surfaces fungi of Solanum tuberosum L

Summary The effects of the herbicides (Ametryne and Paraquat) on soil, root and leaf-surfaces fungi (both zoosporic and terrestrial) inhabiting potato (Solanum tuberosum L.) were generally inconsistent. They were almost toxic to the total count and the toxicity extended till the end of experimentation period (4 weeks). Most of the fungal species were also poisoned at certain periods and doses. Some fungal species showed two reactions the promotive one in shorter periods and the inhibitory response after longer periods. When the herbicides were incorporated with liquid medium, most of the tested fungal species were inhibited even at the low doses. Emericella nidulans and Trichoderma harzianum were the most resistant species. Some species were resistant to Paraquat but sensitive to Ametryne and vice versa.