Lucile Sage

Mycoflora of soil around the Dead Sea. II: Deuteromycetes (except Aspergillus and Penicillium)

Summary Samples were taken from the top 10 centimeters of soils from 56 localities along the Dead Sea valley. There were 269 isolates representing 106 species dispatched into 51 genera of Deuteromycetes ( Aspergilius and Pesricillium not included) in addition to 20 sterile mycelia and an unidentified black yeast. The genera Alternaria, Ulocladium and Fusarium were represented respectively by 6, 8 and 10 different species and were the most frequently isolated in the different samples. The most common species were Acremonium strictum, Alternaria alternata, A. chlamydospora, Botryotrichum piluliferum, Botrytis cinerea, Cladosporium cladosporioides, Epicoccum nigrum, Fusarium oxysporum, Ulocladium atrum, U. chlamydosporum, U. consortiale . One new Bipolaris species was isolated, which has been the object of two other papers (submitted for publication). One thermophile was found: Scytalidium thermophilum . No strict halophiles but only halotolerant species were obtained. As already noticed in the first part of this work, there does not seem to be a fungus flora that is characteristic of desert soil or highly saline soil. Some ubiquitous soil fungi seem to be able to adapt to these extreme conditions.

Mycoflora of soil around the Dead Sea. I: Ascomycetes (including Aspergillus and Penicillium), basidiomycetes, zygomycetes

Summary Samples were taken from the top 10 centimeters of soils from 56 localities along the Dead Sea valley. There were 246 isolates representing 90 species dispatched into 23 genera of Ascomycetes (including Aspergillus and Penicillium ) and Zygomycetes in addition to some unidentified Ascomycetes and Basidiomycetes. The genera Aspergillus and Penicillium were represented by a great number of species. Two new species of Aspergillus ( niger group) and two new varieties of Microascus have been isolated. No strict thermophiles or halophiles were obtained. There does not seem to be a fungus flora that is characrerisric of desert soil or highly saline soil. Some ubiquitous soil fungi seem to be able to adapt to these extreme conditions.

Differences in fungal communities associated to Festuca paniculata roots in subalpine grasslands

Mycorrhizal fungi or endphytes colonize plant roots and their occurrence and composition depend on biotic and abiotic characteristics of the ecosystem. We investigated the composition of these microbial communities associated with Festuca paniculata, a slow growing species, which dramatically impacts functional plant diversity and the recycling of organic matter in subalpine grasslands. F. paniculata individuals from both mown and unmown grasslands were randomly collected and the microscopic observation of the plant roots revealed a difference in fungal colonization according to management. The ITS regions of root-associated fungi were amplified, cloned and sequenced. Bioinformatic analysis revealed a total of 43 and 35 phylotypes in mown and unmown grasslands respectively, highlighting a remarkable difference in the composition between both fungal communities. The phylotypes were assigned to 9 classes in which two classes Eurotiomycetes and Lecanoromycetes were specific to mown grasslands, while Tremellomycetes were specific to unmown grasslands and only five phylotypes were common to both locations. The comparative analysis of fungal lifestyles indicated the dominance of saprobes and a large proportion of endophytes compared to the mycorrhizal fungi (7/1 and 11/2 phylotypes in mown and unmown grasslands, respectively). Endophyte richness was greater in the unmown gassland than in the mown grassland and their relative proportion was twice higher. Our results suggest that endophytes may offer potential resources to F. paniculata and play an important role in the regulation of plant diversity.

Soil mycoflora from the Dead Sea Oases of Ein Gedi and Einot Zuqim (Israel)

Samples were taken from the top 10 cm of soils from 24 points in the Ein Gedi area. Among 329 isolates, 142 species were identified: 11 genera of ascomycetes, one genus of coelomycetes, 28 genera of hyphomycetes, 7 genera of zygomycetes and one yeast, in addition to some unidentified basidiomycetes. The hyphomycetes were represented by 17 dematiaceous, 9 mucedinaceous and two tuberculariaceous. Melanconiaceous and stilbellaceous genera were not found. Two new varieties of Microascus recently described were reisolated. No strict thermophiles or halophiles were obtained. There is apparently no very characteristic or specific fungal flora of the Dead Sea Oases although it was different from that found in the desert soil surrounding this area.

Fungal microflora biodiversity as a function of pollution in Oued Sebou (Morocco)

An inventory of the fungal microflora present in sediments collected at 11 sites along Oued Sebou has been established. The influence of some climatic parameters (temperature, rainfall) and of pollution on the composition of the fungal communities has been questioned. Emericella nidulans, Eurotium amstelodami, Neosartotya fisheri var. glabrum (Ascomycetes), Dreschslera biseptata (Dematiaceae), Penicillium citrinum (Mucedinaceae) and Phoma sp. (Sphaeropsidale) can be considered as strains sensitive to pollution. Penicillium janthelinum, Trichoderma koningii (Mucedinaceae) and Candida albicans (Yeast) were found only at the most polluted sites; Talaromyces flavus (Ascomycete) Rhodotorula rubra, Saccharomyces cerevisiae (Yeasts) and Fusarium oxysporum (Tuberculariales) were more often found at heavily polluted sites than at lightly polluted ones.

Potentiality of the cox1 gene in the taxonomic resolution of soil fungi

We explored the potential of the cox1 gene in the species resolution of soil fungi and compared it with the nuclear internal transcribed spacer (ITS) and small subunit (SSU)-rDNA. Conserved primers allowing the amplification of the fungal cox1 gene were designed, and a total of 47 isolates of Zygomycota and Ascomycota were investigated. The analysis revealed a lack of introns in >90% of the isolates. Comparison of the species of each of the six studied genera showed high interspecific sequence polymorphisms. Indeed, the average of nucleotide variations (4.2-11%) according to the genus, due mainly to the nucleotide substitutions, led to the taxonomic resolution of all the species studied regarding both ITS and SSU-rDNA, in which <88% were discriminated. The phylogenetic analysis performed after alignment of the cox1 gene across distant fungal species was in accordance with the well-known taxonomic position of the species studied and no overlap was observed between intra- and interspecific variations. These results clearly demonstrated that the cox1 sequences could provide good molecular markers for the determination of the species composition of environmental samples and constitute an important advance to study soil fungal biodiversity.

BIOTIC AND ABIOTIC FACTORS GOVERNING THE ANTIFUNGAL ACTIVITY OF MICROFUNGI. A MULTIVARIATE STATISTICAL APPROACH

Summary The antifungal activity of 379 strains of microfungi from the collection of the University of Grenoble has been tested against Cryptococcus neoformans, Candida albicans , and Candida tropicalis . The results showed that the activity of a strain was not species specific. Strains of the same species but of different origins could exhibit different activities. To determine the factors governing this behavior, each microfungal strain has been described by means of parameters taking into account biochemical, physiological and ecological information. Correspondence Factor Analyses carried out from a subsection of a Burt matrix, which allowed us to structure the original data, have shown that it was possible to select a strain having a particular antifungal activity from its biotic and abiotic characteristics. The usefulness of our statistical approach and the methodological consequences of our findings on the significance of screening tests with microorganisms are discussed.

New Strains from Israel in the Aspergillus niger Group

Summary In the course of a survey of the mycoflora of the Dead Sea area, two new species of Aspergillus have been isolated. The species are considered as members of the niger group, but did not correspond to any other described in this group up to now. A description and some physiological properties of these species, named Aspergillus homomorphus and Aspergillus pseudo-heteromorphus are reported.

Autochthonous ascomycetes in depollution of polychlorinated biphenyls contaminated soil and sediment.

We investigated the capacity of a consortium of ascomycetous strains, Doratomyces nanus, Doratomyces purpureofuscus, Doratomyces verrucisporus, Myceliophthora thermophila, Phoma eupyrena and Thermoascus crustaceus in the mycoremediation of historically contaminated soil and sediment by polychlorinated biphenyls (PCBs). Analyses of 15 PCB concentrations in three mesocosms containing soil from which the fungal strains had previously been isolated, revealed significant PCB depletions of 16.9% for the 6 indicator PCBs (i-PCBs) and 18.7% for the total 15 PCBs analyzed after 6months treatment. The degradation rate did not statistically vary whether the soil had been treated with non-inoculated straw or colonized straw or without straw and inoculated with the consortium of the six strains. Concerning the sediment, we evidenced significant depletions of 31.8% for the 6 i-PCBs and 33.3% for the 15 PCB congeners. The PCB depletions affected most of the 15 PCBs analyzed without preference for lower chlorinated congeners. Bioaugmented strains were evidenced in different mesocosms, but their reintroduction, after six months treatment, did not improve the rate of PCB degradation, suggesting that the biodegradation could affect the bioavailable PCB fraction. Our results demonstrate that the ascomycetous strains potentially adapted to PCBs may be propitious to the remediation of PCB contaminated sites.

Exserohilum sodomii, a new species isolated from soil near the Dead Sea (Israel)

Exserohilum sodomii sp. nov., is described. This new species was isolated from a soil sample from the Dead Sea surroundings. Its main physiological properties, as well as the influence of temperature and salts concentration in the culture medium on growth and morphology of the fungus were investigated and discussed.