Actinobacteria are found spread widely in nature and particular attention is given to their role in the production of various bioactive secondary metabolites. Tests on soil samples show that there can be a diversity of actinomycetes depending on the climate, the area it is growing in, how dry the soil is, and the quality of the soil. However, it was agreed after tests in Yunnan, China, that the genus Streptomyces sp. is most important in ecological function, representing up to 90% of all soil actinomycetes, and therefore helping to show the important characteristics needed of the soil actinomycete population. Streptomycete compounds are used for other biological activities, not just for antibiotics. It has been found that metabolites can be broadly divided into four classes: (1) regulatory activities in compounds, these include consideration of growth factors, morphogenic agents and siderophores, and plants promoting rhizobia; (2) antagonistic agents, these include antiprotozoans, antibacterials, antifungals, as well as antivirals; (3) agrobiologicals, these include insecticides, pesticides, and herbicides; and (4) pharmacological agents, these include neurological agents, immunomodulators, antitumorals, and enzyme inhibitors. It is found that Streptomyces hygroscopicus is one of the very best examples because it secretes in excess of 180 secondary metabolites to locate simultaneous bioactivities for a given compound. Increasingly, both its agricultural and pharmacological screenings are being used in conjunction with antimicrobial tests and have revealed several unusual aerobiological and therapeutic agents, which were hitherto unknown for biological use as antibiotics. Since streptomycetes are now being used increasingly to screen for antimicrobial activity, reports show the existence of secondary metabolites with other activities that may have been missed. Currently, nearly 17% of biologically active secondary metabolites (nearly 7600 out of 43,000) are known from streptomycetes. It has been found that soil streptomycetes are the main source used by bioactive secondary metabolites. However, recently there have been many and varied types of structurally unique and biologically active secondary metabolites found and obtained from marine actinomycetes, including those from the genus Streptomyces. Also, compounds that are synthesized by streptomycetes exhibit extreme chemical diversity. Diverse form made from from simple amino acid

Three species of edible desert truffles, Terfezia arenaria, Terfezia claveryi, and Tirmania pinoyi associated with Helianthemum guttatum in Algeria were examined in this study. The mycorrhizal synthesis between the three species of desert truffles and Helianthemum guttatum was carried out with two different methods: (i) under axenic conditions on perlite permeated by a nutritive solution, by inoculating the seedlings with mycelial fragments; (ii) under gnotoxenic conditions on natural substrates, by inoculating plants with spore suspensions. The method of synthesis did not have any influence on the type of mycorrhizae. The desert truffles formed two types of mycorrhizae according to the fertility of the substrate: ectomycorrhizae without sheath, in the phosphorus rich substrates, or ectendomycorrhizae, also without sheath, in the phosphorus deficient substrates. Primordial ascomata were obtained in the syntheses involving polysporous inocula. Key words: ectomycorrhizae, ectendomycorrhizae, Helianthemum guttatum, Terfezia, Tirmania.

Six Cistaceae species, Helianthemum ledifolium, Helianthemum lippii, Fumana procumbens, Cistus albidus, Cistus incanus, Cistus salvifolius, and Pinus halepensis (Aleppo pine) were inoculated with three mycorrhizal desert truffles, Terfezia leptoderma, Terfezia boudieri, and Terfezia claveryi under greenhouse conditions, on soil originating from desert truffle natural habitat in Algeria. The syntheses have led to the formation of typical endomycorrhizae in annual Cistaceae (H. ledifolium) and perennial ones (H. lippii and F. procumbens) and an ectomycorrhiza with a less developed sheath in Cistus species and Aleppo pine. These results demonstrate the plasticity of Terfezia species to form different mycorrhizal types. The formation of an endomycorrhiza with H. ledifolium and F. procumbens and a sheathing ectomycorrhiza with P. halepensis inoculated by T. leptoderma in in vivo culture conditions was obtained for the first time.

Morphological and phylogenetic analyses of large ribosomal subunit (28S rDNA) and internal transcribed spacer (ITS rDNA) of Terfezia samples collected from several bioclimatic zones in Algeria and Spain revealed the presence of six distinct Terfezia species: T. arenaria, T. boudieri, T. claveryi; T. eliocrocae (reported here for the first time from North Africa), T. olbiensis, and a new species, T. crassiverrucosa sp. nov., proposed and described here, characterized by its phylogenetic position and unique combination of morphological characters. A discussion on the unresolved problems in the taxonomy of the spiny-spored Terfezia species is conducted after the present results.

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