Heavy metal resistant of E. coli isolated from wastewater sites in Assiut City, Egypt.

Twelve isolates of E. coli were isolated from wastewater of El-Malah canal located in Assiut, Egypt and were checked for their heavy metal tolerance. One isolate has tested for its multiple metal resistances and found to be plasmid mediated with molecular weights 27 and 65 kb for hexa- and trivalent chromium. It was identified as E. coli ASU 7. Its minimal inhibitory concentration (MIC) for Cu(2+), Co(2+), Ni(2+), Zn(2+), Cr(6+), Cr(3+), Cd(2+) and Pb(2+) were 1.57, 2.55, 1.7, 9.17, 0.48, 7.69, 4.4 and 3.1 mM, respectively. Growth kinetics was determined under Cr(6+) and Cr(3+) stress. SDS-PAGE of protein profile shows that 10 ppm (0.19 mM) of Cr(6+) induces new protein with molecular weight 23 kDa.

Isolation, characterization of heavy metal resistant strain of Pseudomonas aeruginosa isolated from polluted sites in Assiut city, Egypt.

Sixty six isolates of Pseudomonas spp. were isolated from wastewater of El-Malah canal located in Assiut, Egypt and were checked for their heavy metal tolerance. One isolate has tested for its multiple metal resistances and found to be plasmid mediated with molecular weight 27 Kb for nickel and lead. It was identified as Pseudomonas aeruginosa ASU 6a. Its minimal inhibitory concentration (MIC) for Cu(2+), Co(2+), Ni(2+), Zn(2+), Cr(3+), Cd(2+)and Pb(2+) were 6.3, 5.9, 6.8, 9.2, 5.8, 4.4, and 3.1 mM, respectively. Growth kinetics and the maximum adsorption capacities were determined under Ni(2+) and Pb(2+) stress. The latter heavy metals induced potassium efflux and were used as indicator for plasma membrane permeabilization.

Bacillus species associated with wheat and sorghum dusts from combine harvester.

14 species and one species variety belonging to genus Bacillus were collected from wheat and sorghum dusts of combine harvester on either nutrient agar (NA) or sheep blood agar (SBA) at 30 degrees C (14 spp.), 45 degrees C (13 spp.) and 55 degrees C (5 spp.). The flora of Bacillus on both substrates and on the two isolation media were basically similar and the most common species were B. brevis, B. cereus, B. circulans, B. coagulans, B. licheniformis, B. stearothermophilus and B. subtilis. The total viable count of airborne bacteria in the two atmospheres were lower in wheat than in sorghum hay sites. The percentage count of haemolytic bacteria on SBA comprised 10% and 15% of the total viable count, respectively.

Selective isolation of fluorescent and nonfluorescent Pseudomonas species from Sohag Governorate (Upper Egypt).

Three hundred and fourty nine isolates belonging to ten different species of Pseudomonas were isolated and identified from soil and water samples on four selective isolation media: Modified Trypticase soy agar (TSA), ACC-agar containing ampicillin-chloramphenicol-cycloheximide, Nitrate plus organic acid agar and Tryptophan substrate agar. The fluorescent species were P. putida (21.2% of the total Pseudomonas species), P. fluorescens (15.8%), P. aeruginosa (9.7%) and P. aureobaciens (2.6%), while the nonfluorescent species were P. stutzeri (12.4%), P. alcaligenes (11.2%), P. pseudoalcaligenes (9.5%), P. mendocina (8.3%), P. lemoignei (5.7%) and P. ruhlandii (3.4%). Modified TSA and ACC media were efficient for the isolation of both fluorescent and nonfluorescent species, whereas Nitrate and Tryptophan media were more selective for the isolation of nonfluorescent species. The optimum temperature for the isolation of different species ranged between 20 degrees and 37 degrees C.

Acetylene reduction by Rhodospirillaceae from the Aswan High Dam Lake.

Potential nitrogen-fixing freshwater photosynthetic bacteria of 32 isolates from the Aswan High Dam Lake were investigated using the acetylene reduction technique to ascertain the magnitude of their contribution of fixed nitrogen to the ecosystem. The superior nitrogen-fixing Rhodospirillaceae wereRhodocyclus gelatinosus andRhodomicrobium vannielii followed byRhodobacter capsulatus, Rhodopseudomonas viridis andRhodopseudomonas palustris. High and moderate nitrogenase activities (534 to 1528 nmol ethylene produced/4 ml/h) were found in 56% of the isolates, while the remainder showed low activities (76 to 477 nmol ethylene produced/4 ml/h).

Fungal flora associated with combine harvester wheat and sorghum dusts from Egypt.

107 species and 8 species varieties belonging to 44 genera were collected from combine harvester wheat and sorghum dusts (35 genera and 91 species + 4 varieties) and from the atmosphere of their hay sites (26 genera and 69 species + 4 varieties) on glucose- and cellulose-Czapek's Dox agar at 28 degrees C and 45 degrees C. The mycoflora of wheat and sorghum dusts were basically similar on the two types of media and the most common fungi were: Alternaria alternata, Aspergillus flavus, A. fumigatus, A. niger, A. ochraceus, A. sydowii, A. terreus, Cochliobolus spicifer, Emericella nidulans, Fusarium moniliforme, Penicillium chrysogenum, P. duclauxii, P. funiculosum and P. oxalicum. Truly thermophilic species were frequently encountered from the two substrates: Chaetomium thermophilum, Humicola grisea var. thermoidae, H. insolens, Malbranchea pulchella var., sulphurea, Rhizomucor pusillus, Sporotrichum thermophilum, Talaromyces thermophilus, Thermoascus thermophilus and Thermomyces lanuginosus. The airborne fungi in the two atmospheres were basically similar and the most prevalent species were members of Alternaria (1 species), Aspergillus (18 species + 2 varieties), Chaetomium (2 species), Cochliobolus(3 species), Emericella (3 species + 2 varieties), Fusarium (3 species), Mucor (1 species), Penicillium (14 species) and Stachybotrys (1 species).

Keratinophilic and other fungi isolated from combine harvester wheat and sorghum dusts and from the atmosphere of winnow sites in Egypt.

Three methods were used for the isolation of fungi in the present investigation: the dilution-plate method, hair-baiting technique with horse hairs and the "exposed plate" method. Sabouraud's glucose agar at 28 degrees C was also used as isolation medium. 102 species and 2 species varieties belonging to 36 genera were collected from combine harvester wheat and sorghum dusts and from the atmosphere of hay or winnow sites. Chrysosporium was represented by 6 species: C. asperatum, C. indicum, C. keratinophilum, C. merdarium, C. pannorum and C. tropicum. Several filamentous fungi tolerating high levels of cycloheximide and other moulds were frequently encountered in the two types of dusts and in the two atmospheres, such as members of Acremonium, Alternaria, Aspergillus, Cladosporium, Emericella, Eupenicillium, Fusarium, Paecilomyces, Penicillium, Piedraia, Rhizopus, Scopulariopsis and others.

Mycoflora and mycotoxin-producing fungi of air-dust particles from Egypt.

Using the dilution-plate method, 27 genera and 64 species were collected from 20 air-dust samples on glucose - (24 genera and 57 species) and cellulose - (21 genera and 45 species) Czapek's agar at 28 degrees C. There are basic similarities between the mycoflora of air-dust on the two media and the most prevalent species were Aspergillus niger, A. flavus, A. ochraceus, A. terreus, A. versicolor, Penicillium chrysogenum, P. funiculosum, Alternaria alternata, Cladosporium herbarum, Fusarium oxysporum, Rhizopus stolonifer and Trichoderma viride. Chaetomium globosum, Stachybotrys chartarum, Humicola grisea and Arthrobotrys oligospora were common only on cellulose agar plates. Extracts of mycelium from 25 isolates were tested with brine schrimp (Artemia salina); of these 23 displayed varying degrees of toxicity. Thin layer chromatographic analysis of 12 isolates of Aspergillus flavus revealed that 4 strains were producing detectable aflatoxin. Zearalenone production was noted for 3 out of 5 strains of Fusarium oxysporum and 2 out of 5 strains of F. solani.

Mycotoxins producing fungi and mycoflora of air-dust from Taif, Saudi Arabia.

Using the dilution plate method, 70 species and 31 genera were collected from 20 dust samples on glucose (28 genera and 64 species) and cellulose Czapek's agar (22 genera and 46 species) at 28 degrees C. The most common fungi were Aspergillus niger, A. flavus, A. flavus var. columnaris, Phoma glomerata, Fusarium oxysporum, Penicillium chrysogenum and Mucor racemosus; and A. nidulans, Phoma humicola, Drechslera spicifera and Stachybotrys chartarum on the two media, respectively. Toxicity test showed that about 85% of the isolates tested were toxic to brine shrimp (Artemia salina). Thin layer chromatographic analysis revealed that 13 out of 23 toxic isolates produced known mycotoxins. Toxins identified were: aflatoxins B1 and B2, Kojic acid and trichodermine.