Effects of storage time and temperature on the infectivity and effectiveness of Frankia entrapped in polyacrylamide gel.

Four Frankia-Casuarina endosymbiont strains were tested for their infectivity and effectiveness on C. equisetifolia plants after 1 d, 3 and 6 months of Frankia storage at 7, 28 and 40 degrees C as liquid-cultures and polyacrylamide gel (PAG)-immobilized inocula. At lower temperature the number of nodules was the same or higher than control for liquid inocula except after 6 months of storage. For the PAG-entrapped Frankia lower numbers of nodules were recorded due to the use of high Frankia titers. In general, the results showed comparable plant dry mass, total nitrogen, root to shoot and nodules to plant ratios at lower temperature treatments. Increasing time and temperature was accompanied with reduced infectivity and effectiveness on inoculated plants. No nodulation was scored on plants inoculated with liquid and PAG-entrapped inocula stored at 40 degrees C for 6 months; subsequently, plant growth was inhibited. The variations in results obtained for different strains and treatments lead to variations in plant nitrogen-fixing ability. The use of PAG as a carrier for different Frankia strains is suggested; the recommended storage temperature for PAG-immobilized Frankia in 7-28 degrees C for up to 3 months.

Composition of Casuarina leaf litter and its influence on Frankia-Casuarina symbiosis in soil.

Plant needles of Casuarina equisetifolia were collected and analyzed in parallel with soil analysis. In three strains of Frankia--symbionts of Casuarina--their infectivity and plant performance was determined in vitro after soil amendment with different leaf litter concentrations. Only one strain was able to nodulate the plant at all litter concentrations (0.5, 3 and 5%) although the nodules were very small. However, all treated plants grew poorly; their growth was reduced by approximately 90% (for 5% litter concentration) compared to plants grown on untreated soil, on the basis of total dry mass. Inhibition of nodulation can be attributed to high concentrations of some elements and compounds that were either found in C. equisetifolia litter or originally found in soil (i.e. chloride, cyanide, copper, manganese and phenols). In general, plant growth decreased as more litter was added. Plant total nitrogen content was also reduced after increasing the litter concentration. The inhibitory effect of high litter concentrations was mainly on plant growth and to a lesser extent on plant nodulation by Frankia strains.

Experimental transmission and pathogenicity of some zoosporic fungi to Tilapia fish.

Seventeen fungal species belong to sex genera were recovered from the four organs of Tilapia fish and the most common were Saprolegnia ferax, S. diclina, Achlya dubia, A. americana, A. racemosa and A. flagellata, Dictyuchus sterile, Pythium undulatum and Aphanomyces sp. Severe infection followed by death of all fish was incited by S. parasitica and S. ferax through experiment I. 30-70% of T. nilotica and T. galileae were killed through experiment II by S. parasitica and S. ferax. T. galileae was more susceptible to fungal infection than T. nilotica.

Effect of pH and organic matter on the toxicity of heavy metals to growth of some fungi.

Increasing the pH from 5 to 9 decreased the toxicity of mercuric chloride, zinc sulfate, lead nitrate, copper sulfate and nickel chloride toward the growth of Aspergillus flavus, Penicillium chrysogenum, Cunninghamella echinulata, Myrothecium verrucaria and Phoma humicola. On the other hand, the toxicity of cadmium chloride was increased by the increasing pH. Also increasing the concentration of organic matter (peptone and yeast extract) from 0.5 to 1.5% induced a significant reduction in the toxicity of all heavy metals toward the growth of all test fungi.

Keratinophilic and saprophytic fungi isolated from students' nails in Egypt.

In order to determine the presence of dermatophytes and saprophytes in healthy toe and finger nails, 120 students (60 male and 60 female) from preparatory schools at Sohag Governorate (Upper Egypt) were studied. 54 species in addition to 3 varieties belonging to 17 genera were isolated. Six species of true dermatophytes were collected: Microsporum audouinii var. rivalieri, M. cookei, Trichophyton mentagrophytes, T. simii, T. terrestre and T. verrucosum. Chrysosporium, a well-known keratinophilic genus, was prevalent and represented by 7 species (C. asperatum, C. indicum, C. keratinophilum, C. luteum, C. pannorum, C. tropicum and Chrysosporium state of Thielavia sepedonium). The commonest saprophytes in order of frequency were members of the genera Aspergillus, Penicillium, Alternaria, Scopulariopsis, Fusarium, Paecilomyces, Chaetomium, Syncephalastrum, Mucor, Rhizopus and Acremonium.

The occurrence of keratinophilic fungi in sewage sludge from Egypt.

The keratinophilic fungi of 40 sewage sludge samples from Upper Egypt were studied using a goat hair-baiting technique. 43 species representing 22 genera were isolated, 17 species of which were dermatophytes and closely related fungi: Chrysosporium state of Arthroderma tuberculatum, C. asperatum, C. georgii, C. indicum, C. keratinophilum, C. pseudomerdarium, C. queenslandicum, Chrysosporium state of Thielavia sepedonium, C. tropicum, Microsporum cookei, M. gypseum, Myceliophthora anamorph of Corynascus novoguineensis, M. vellerea and Trichophyton terrestre. 26 species of cycloheximide resistant fungi were collected and these included members of Acremonium, Aspergillus, Alternaria, Chaetomium, Cladosporium, Cunninghamella, Emericella, Fusarium, Geotrichum, Penicillium and others.

Effects of temperature and pH on growth and oospore production of three water-borne Pythium.

Temperature and pH significantly affect the growth and oospore production of the test fungi. The optimum temperature for mycelial production was nearly the same on both solid and liquid media. H-ion concentration has milder effect than temperature. The optimum temperature and pH value for oospore production agree remarkably with their respectives for growth.

Water-borne fungi in the River Inn, Innsbruck (Austria).

Pythium, Saprolegnia and Achlya were the basic components of the river mycoflora. Occurrence and periodicity of the fungal genera and species exhibited three different patterns during the different months of this investigation.