Halophilic Actinomycetes in 1 Saharan Soils of Algeria: Isolation, Taxonomy and Antagonistic Properties

The diversity of a population of 52 halophilic actinomycetes was evaluated by a polyphasic approach, which showed the presence of Actinopolyspora, Nocardiopsis, Saccharomonospora, Streptomonospora and Saccharopolyspora genera. One strain was considered to be a new member of the last genus and several other strains seem to be new species. Furthermore, 50% of strains were active against a broad range of indicators and contained genes encoding polyketide synthetases and nonribosomal peptide synthetases

Identification of actinomycetes from plant rhizospheric soils with inhibitory activity against Colletotrichum spp., the causative agent of anthracnose disease

<p>Abstract</p> <p>Background</p> <p><it>Colletotrichum </it>is one of the most widespread and important genus of plant pathogenic fungi worldwide. Various species of <it>Colletotrichum </it>are the causative agents of anthracnose disease in plants, which is a severe problem to agricultural crops particularly in Thailand. These phytopathogens are usually controlled using chemicals; however, the use of these agents can lead to environmental pollution. Potential non-chemical control strategies for anthracnose disease include the use of bacteria capable of producing anti-fungal compounds such as actinomycetes spp., that comprise a large group of filamentous, Gram positive bacteria from soil. The aim of this study was to isolate actinomycetes capable of inhibiting the growth of <it>Colletotrichum </it>spp, and to analyze the diversity of actinomycetes from plant rhizospheric soil.</p> <p>Results</p> <p>A total of 304 actinomycetes were isolated and tested for their inhibitory activity against <it>Colletotrichum gloeosporioides </it>strains DoA d0762 and DoA c1060 and <it>Colletotrichum capsici </it>strain DoA c1511 which cause anthracnose disease as well as the non-pathogenic <it>Saccharomyces cerevisiae </it>strain IFO 10217. Most isolates (222 out of 304, 73.0%) were active against at least one indicator fungus or yeast. Fifty four (17.8%) were active against three anthracnose fungi and 17 (5.6%) could inhibit the growth of all three fungi and <it>S. cerevisiae </it>used in the test. Detailed analysis on 30 selected isolates from an orchard at Chanthaburi using the comparison of 16S rRNA gene sequences revealed that most of the isolates (87%) belong to the genus <it>Streptomyces </it>sp., while one each belongs to <it>Saccharopolyspora </it>(strain SB-2) and <it>Nocardiopsis </it>(strain CM-2) and two to <it>Nocardia </it>(strains BP-3 and LK-1). Strains LC-1, LC-4, JF-1, SC-1 and MG-1 exerted high inhibitory activity against all three anthracnose fungi and yeast. In addition, the organic solvent extracts prepared from these five strains inhibited conidial growth of the three indicator fungi. Preliminary analysis of crude extracts by high performance liquid chromatography (HPLC) indicated that the sample from strain JF-1 may contain a novel compound. Phylogenetic analysis revealed that this strain is closely related to <it>Streptomyces cavurensis </it>NRRL 2740 with 99.8% DNA homology of 16S rRNA gene (500 bp).</p> <p>Conclusion</p> <p>The present study suggests that rhizospheric soil is an attractive source for the discovery of a large number of actinomycetes with activity against <it>Colletotrichum </it>spp. An interesting strain (JF-1) with high inhibitory activity has the potential to produce a new compound that may be useful in the control of <it>Colletotrichum </it>spp.</p

Isolation, Phylogenetic Analysis and Anti-infective Activity Screening of Marine Sponge-Associated Actinomycetes

Terrestrial actinomycetes are noteworthy producers of a multitude of antibiotics, however the marine representatives are much less studied in this regard. In this study, 90 actinomycetes were isolated from 11 different species of marine sponges that had been collected from offshore Ras Mohamed (Egypt) and from Rovinj (Croatia). Phylogenetic characterization of the isolates based on 16S rRNA gene sequencing supported their assignment to 18 different actinomycete genera representing seven different suborders. Fourteen putatively novel species were identified based on sequence similarity values below 98.2% to other strains in the NCBI database. A putative new genus related to Rubrobacter was isolated on M1 agar that had been amended with sponge extract, thus highlighting the need for innovative cultivation protocols. Testing for anti-infective activities was performed against clinically relevant, Gram-positive (Enterococcus faecalis, Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria, fungi (Candida albicans) and human parasites (Leishmania major, Trypanosoma brucei). Bioactivities against these pathogens were documented for 10 actinomycete isolates. These results show a high diversity of actinomycetes associated with marine sponges as well as highlight their potential to produce anti-infective agents

Microbial diversity and biogeography in Arctic soils

Microorganisms dominate terrestrial environments in the polar regions and Arctic soils are known to harbour significant microbial diversity, far more diverse and numerous in the region than was once thought. Furthermore, the geographic distribution and structure of Arctic microbial communities remains elusive, despite their important roles in both biogeochemical cycling and in the generation and decomposition of climate active gases. Critically, Arctic soils are estimated to store over 1500 Pg of carbon and thus, have the potential to generate positive feedback within the climate system. As the Arctic region is currently undergoing rapid change, the likelihood of faster release of greenhouse gases such as CO2 , CH4 and N2 O is increasing. Understanding the microbial communities in the region, in terms of their diversity, abundance and functional activity, is key to producing accurate models of greenhouse gas release. This review brings together existing data to determine what we know about microbial diversity and biogeography in Arctic soils

Study of the diversity of culturable actinomycetes in the North Pacific and Caribbean coasts of Costa Rica

In this study, 137 actinomycetes were isolated from subtidal marine sediments in the North Pacific and Caribbean coasts of Costa Rica. Bioinformatics analysis of the 16S rRNA gene sequences assigned the isolates to 15 families and 21 genera. Streptomyces was the dominant genus while the remaining 20 genera were poorly represented. Nearly 70% of the phylotypes presented a coastal-restricted distribution whereas the other 30% were common inhabitants of both shores. The coastal tropical waters of Costa Rica showed a high diversity of actinomycetes, both in terms of the number of species and phylogenetic composition, although significant differences were observed between and within shores. The observed pattern of species distribution might be the result of several factors including the characteristics of the ecosystems, presence of endemic species and the influence of terrestrial runoff.University of Aberdeen/[]//EscociaNational Institutes of Health/[U01 TW007404-01 ICBG]/NIH/Estados UnidosUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de BiologíaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Químic