RESUMO
Microbial biodiversity provides an increasingly important source of medically and industrially useful compounds. We have isolated 14 actinomycete species from a collection of approximately 300 plant stem samples from the upper Amazonian rainforest in Peru. All of the cultured isolates produce substances with inhibitory activity directed at a range of potential fungal and bacterial pathogens. For some organisms, this activity is very broad in spectrum while other organisms show specific activity against a limited number of organisms. Two of these organisms preferentially inhibit bacterial test organisms over eukaryotic organisms. rDNA sequence analysis indicates that these organisms are not equivalent to any other cultured deposits in GenBank. Our results provide evidence of the untapped biodiversity in the form of biologically active microbes present within the tissues of higher plants.
Assuntos
Actinobacteria/genética , Actinobacteria/isolamento & purificação , Biodiversidade , Filogenia , Árvores/microbiologia , Actinobacteria/classificação , Actinobacteria/ultraestrutura , Antibiose , DNA Ribossômico/genética , Dados de Sequência Molecular , Peru , RNA Bacteriano/genética , Análise de Sequência de DNA , Clima TropicalRESUMO
Endophytic streptomycetes have been isolated and characterized from several species of Nothofagus and other plants growing in the southern reaches of Patagonia. No endophytic streptomycete was obtained from any plant species studied in Northern Patagonia. However, from Southern Patagonia, biologically active Streptomyces spp. from several plant species were isolated. Each isolate, as studied by scanning electron microscopy (SEM), has small hyphae, some produce typical barrel-shaped spores in culture and each has some unique hyphal surface structures. Interestingly, although none has any detectable antibacterial killing properties, each has demonstrable killing activity against one or more pathogenic fungi including representative plant pathogenic organisms such as Phytophthora erythroseptica, Pythium ultimum, Sclerotinia sclerotiorum, Mycosphaerella fijiensis, and Rhizoctonia solani. The 16S rDNA sequences of the isolates were distinct from all other genetic accessions of Streptomyces in GenBank. However, isolate C-2 from Chiliotrichum diffusum (Compositae) is identical, in all respects, to isolate C-4 obtained from Misodendrum punctulatum (Loranthaceae). These results confirm that endophytic streptomycetes represent a novel source of biologically active microorganisms.
Assuntos
Antibiose , Fagaceae/microbiologia , Fungos/crescimento & desenvolvimento , Magnoliopsida/microbiologia , Oomicetos/crescimento & desenvolvimento , Streptomyces/crescimento & desenvolvimento , Asteraceae/microbiologia , Loranthaceae/microbiologia , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , Filogenia , Doenças das Plantas/microbiologia , Análise de Sequência de DNA , América do Sul , Streptomyces/classificação , Streptomyces/genética , Streptomyces/ultraestruturaRESUMO
Seimatoantlerium gen. nov., type species, S. tepuiense sp. nov. is proposed for an acervular fungus producing 4-septate, holoblastic conidia with 6-8 unbranched, apical appendages that dehisce as an appendage apparatus and also commonly possessing one or two exogenous basal appendages as well as a pedicel. It is compared with Seimatosporium, Seimatosporiopsis, and other genera. It is epiphytic on Maguireothamnus speciosus, a rubiaceous plant endemic to the tepuis of southeastern Venezuela. It produces the anti-oomycetous anticancer compound, taxol, as shown by immunological and spectroscopic methods. Taxol production is discussed relative to the ability of this fungus to exist in an extremely moist ecosystem, as well as to its relationship to other plant associated fungi.
Assuntos
Antineoplásicos Fitogênicos/isolamento & purificação , Fungos Mitospóricos/química , Paclitaxel/isolamento & purificação , Plantas/microbiologia , Cromatografia em Camada Fina , Ecologia , Espectrometria de Massas , Fungos Mitospóricos/citologia , Fungos Mitospóricos/crescimento & desenvolvimento , Kit de Reagentes para DiagnósticoRESUMO
Seimatoantlerium gen. nov., type species, S.tepuiense sp. nov. is proposed for an acervular fungus producing 4-septate, holobastic conidia with 6-8 unbranched, apical appendages that dehisce as an appendage apparatus and also commonly possessing one or two exogenous basal appendages as well as a pedicel. It is compared with Seimatosporium, Seimatosporiopsis, and other genera. It is epiphytic on Maguireothamnus speciosus, a rubiaceous plant endemic to the tepuis of southeastern Venezuela. It produces the anti-oomycetous anticancer compound, taxol, as shown by immunological and spectroscopic methods. Taxol production is discussed relative to the ability of this fungus to exist in an extremely moist ecosystem, as well as to its relationship to other plant associated fungi. (AU)