Seasonal fluctuations of aquatic fungi recovered from Egyptian soil (Delta Region)

Flooding Duration Affects the Structure of Terrestrial and Aquatic Microbial Eukaryotic Communities

The increasing number and duration of inundations is reported to be a consequence of climate change and may severely compromise non-adapted macroorganisms. The effect of flooding events on terrestrial and aquatic microbial communities is, however, less well understood. They may respond to the changed abiotic properties of their native habitat, and the native community may change due to the introduction of alien species. We designed an experiment to investigate the effect of five different flooding durations on the terrestrial and aquatic communities of eukaryotic microorganism, using the AquaFlow mesocosms. With amplicon sequencing of the small subunit (SSU) and internal transcribed spacer (ITS) rRNA gene regions, we analyzed community compositions directly before and after flooding. Subsequently, they were monitored for another 28 days, to determine the sustainability of community changes. Our results revealed a temporary increase in similarity between terrestrial and aquatic communities according to OTU composition (operational taxonomic unit, serves as a proxy for species). Increased similarity was mainly caused by the transmission of OTUs from water to soil. A minority of these were able to persist in soil until the end of the experiment. By contrast, the vast majority of soil OTUs was not transmitted to water. Flooding duration affected the community structure (abundance) more than composition (occurrence). Terrestrial communities responded immediately to flooding and the flooding duration influenced the community changes. Independent from flooding duration, all terrestrial communities recovered largely after flooding, indicating a remarkable resilience to the applied disturbances. Aquatic communities responded immediately to the applied inundations too. At the end of the experiment, they grouped according to the applied flooding duration and the amount of ammonium and chloride that leached from the soil. This indicates a sustained long-term response of the aquatic communities to flooding events.

Diversity and enzymatic profiling of halotolerant micromycetes from Sebkha El Melah, a Saharan salt flat in southern Tunisia

Twenty-one moderately halotolerant fungi have been isolated from sample ashes collected from Sebkha El Melah, a Saharan salt flat located in southern Tunisia. Based on morphology and sequence inference from the internal transcribed spacer regions, 28S rRNA gene and other specific genes such as β-tubulin, actin, calmodulin, and glyceraldehyde-3-phosphate dehydrogenase, the isolates were found to be distributed over 15 taxa belonging to 6 genera of Ascomycetes: Cladosporium (n = 3), Alternaria (n = 4), Aspergillus (n = 3), Penicillium (n = 5), Ulocladium (n = 2), and Engyodontium (n = 2). Their tolerance to different concentrations of salt in solid and liquid media was examined. Excepting Cladosporium cladosporioides JA18, all isolates were considered as alkali-halotolerant since they were able to grow in media containing 10% of salt with an initial pH 10. All isolates were resistant to oxidative stresses and low temperature whereas 5 strains belonging to Alternaria, Ulocladium, and Aspergillus genera were able to grow at 45°C. The screening of fungal strains for sets of enzyme production, namely, cellulase (CMCase), amylase, protease, lipase, and laccase, in presence of 10% NaCl, showed a variety of extracellular hydrolytic and oxidative profiles. Protease was the most abundant enzyme produced whereas laccase producers were members of the genus Cladosporium.

The history, fungal biodiversity, conservation, and future perspectives for mycology in Egypt

Records of Egyptian fungi, including lichenized fungi, are scattered through a wide array of journals, books, and dissertations, but preliminary annotated checklists and compilations are not all readily available. This review documents the known available sources and compiles data for more than 197 years of Egyptian mycology. Species richness is analysed numerically with respect to the systematic position and ecology. Values of relative species richness of different systematic and ecological groups in Egypt compared to values of the same groups worldwide, show that our knowledge of Egyptian fungi is fragmentary, especially for certain systematic and ecological groups such as Agaricales, Glomeromycota, and lichenized, nematode-trapping, entomopathogenic, marine, aquatic and coprophilous fungi, and also yeasts. Certain groups have never been studied in Egypt, such as Trichomycetes and black yeasts. By screening available sources of information, it was possible to delineate 2281 taxa belonging to 755 genera of fungi, including 57 myxomycete species as known from Egypt. Only 105 taxa new to science have been described from Egypt, one belonging to Chytridiomycota, 47 to Ascomycota, 55 to anamorphic fungi and one to Basidiomycota.

Diversity of peronosporomycete (oomycete) communities associated with the rhizosphere of different plant species

Peronosporomycete (oomycete) communities inhabiting the rhizospheres of three plant species were characterized and compared to determine whether communities obtained by direct soil DNA extractions (soil communities) differ from those obtained using baiting techniques (bait communities). Using two sets of Peronosporomycete-specific primers, a portion of the 5' region of the large subunit (28S) rRNA gene was amplified from DNA extracted either directly from rhizosphere soil or from hempseed baits floated for 48 h over rhizosphere soil. Amplicons were cloned, sequenced, and then subjected to phylogenetic and diversity analyses. Both soil and bait communities arising from DNA amplified with a Peronosporomycetidae-biased primer set (Oom1) were dominated by Pythium species. In contrast, communities arising from DNA amplified with a Saprolegniomycetidae-biased primer set (Sap2) were dominated by Aphanomyces species. Neighbor-joining analyses revealed the presence of additional taxa that could not be identified with known Peronosporomycete species represented in GenBank. Sequence diversity and mean sequence divergence (Theta pi) within bait communities were lower than the diversity within soil communities. Furthermore, the composition of Peronosporomycete communities differed among the three fields sampled and between bait and soil communities based on F(st) and parsimony tests. The results of our study represent a significant advance in the study of Peronosporomycetes in terrestrial habitats. Our work has shown the utility of culture-independent approaches using 28S rRNA genes to assess the diversity of Peronosporomycete communities in association with plants. It also reveals the presence of potentially new species of Peronosporomycetes in soils and plant rhizospheres.