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Actinomycete

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Alan T Bull – 1st expert on this subject based on the ideXlab platform

  • Taxonomy and biotransformation activities of some deep-sea Actinomycetes
    Extremophiles, 1998
    Co-Authors: Joy A. Colquhoun, Spencer C. Heald, Lina Li, Jin Tamaoka, Chiaki Kato, Koki Horikoshi, Alan T Bull

    Abstract:

    Deep-sea soft sediments from trench systems and depths in the northwestern Pacific Ocean ranging from less than 300 to 10,897 m in depth have been analyzed for three target genera of Actinomycetes: Micromonospora, Rhodococcus, and Streptomyces. Only culturable strains, recovered at atmospheric pressure on selective isolation media, have been examined to date. Maximum recoveries of culturable bacteria were greater that 10(7)/ml wet g sediment, but Actinomycetes comprised a small proportion of this population (usually less than 1%). The target Actinomycetes were isolated at all depths except from the Mariana Trench sediments. Actinomycete colonies were defined initially on the basis of colony morphologies, and preliminary identification then was made by chemotaxonomic tests. Pyrolysis mass spectrometry (PyMS) of deep-sea mycolic acid-containing Actinomycetes gave excellent correspondence with numerical (phenetic) taxonomic analyses and subsequently was adopted as a rapid procedure for assessing taxonomic diversity. PyMS analysis enabled several clusters of deep-sea rhodococci to be distinguished that are quite distinct from all type strains. 16S rRNA gene sequence analysis has revealed that several of these marine rhodococci have sequences that are very similar to certain terrestrial species of Rhodococcus and to Dietzia. There is evidence for the intrusion of terrestrial runoff into these deep trench systems, and the inconsistency of the phenotypic and molecular taxonomies may reflect recent speciatiion events in Actinomycetes under the high-pressure conditions of the deep sea. The results of DNA-DNA pairing experiments point to the novelty of Rhodococcus strains recovered from hadal depths in the Izu Bonin Trench. Biotransformation studies of deep-sea bacteria have focused on nitrile compounds. Nitrile-metabolizing bacteria, closely related to rhodococci, have been isolated that grow well at low temperature, high salt concentrations, and high pressures, suggesting that they are of marine origin or have adapted to the deep-sea environment.

Paul R. Jensen – 2nd expert on this subject based on the ideXlab platform

  • hybrid isoprenoid secondary metabolite production in terrestrial and marine Actinomycetes
    Current Opinion in Biotechnology, 2010
    Co-Authors: Kelley A Gallagher, William Fenical, Paul R. Jensen

    Abstract:

    Terpenoids are among the most ubiquitous and diverse secondary metabolites observed in nature. Although Actinomycete bacteria are one of the primary sources of microbially derived secondary metabolites, they rarely produce compounds in this biosynthetic class. The terpenoid secondary metabolites that have been discovered from Actinomycetes are often in the form of biosynthetic hybrids called hybrid isoprenoids (HIs). HIs include significant structural diversity and biological activity and thus are important targets for natural product discovery. Recent screening of marine Actinomycetes has led to the discovery of a new lineage that is enriched in the production of biologically active HI secondary metabolites. These strains represent a promising resource for natural product discovery and provide unique opportunities to study the evolutionary history and ecological functions of an unusual group of secondary metabolites.

  • nitropyrrolins a e cytotoxic farnesyl α nitropyrroles from a marine derived bacterium within the Actinomycete family streptomycetaceae
    Journal of Natural Products, 2010
    Co-Authors: Hak Cheol Kwon, Paul R. Jensen, Ana Paula D M Espindola, Jinsoo Park, Alejandra Prietodavo, Mickea Rose, William Fenical

    Abstract:

    Five new farnesyl-α-nitropyrroles, nitropyrrolins A–E (1–5), were isolated from the saline culture of the marine Actinomycete strain CNQ-509. This strain belongs to the “MAR4” group of marine Actinomycetes, which have been demonstrated to be a rich source of hybrid isoprenoid secondary metabolites. The structures of the nitropyrrolins are composed of α-nitropyrroles with functionalized farnesyl groups at the C-4 position. These compounds are the first examples of naturally-occurring terpenyl-α-nitropyrroles. Chemical modifications, including one-step acetonide formation from an epoxide, and application of the modified Mosher method, provided the full stereostructures and absolute configurations of these compounds. Several of the nitropyrrolins, nitropyrrolin D in particular, are cytotoxic toward HCT-116 human colon carcinoma cells, but show weak to little antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA).

  • culturable marine Actinomycete diversity from tropical pacific ocean sediments
    Environmental Microbiology, 2005
    Co-Authors: Paul R. Jensen, Tracy J Mincer, Erin A Gontang, Chrisy Mafnas, William Fenical

    Abstract:

    Author(s): Jensen, Paul R; Gontang, Erin; Mafnas, Chrisy; Mincer, Tracy J; Fenical, William | Abstract: Actinomycetes were cultivated using a variety of media and selective isolation techniques from 275 marine samples collected around the island of Guam. In total, 6425 Actinomycete colonies were observed and 983 (15%) of these, representing the range of morphological diversity observed from each sample, were obtained in pure culture. The majority of the strains isolated (58%) required seawater for growth indicating a high degree of marine adaptation. The dominant Actinomycete recovered (568 strains) belonged to the seawater-requiring marine taxon ‘Salinospora’, a new genus within the family Micromonosporaceae. A formal description of this taxon has been accepted for publication (Maldonado et al., 2005) and includes a revision of the generic epithet to Salinispora gen. nov. Members of two major new clades related to Streptomyces spp., tentatively called MAR2 and MAR3, were cultivated and appear to represent new genera within the Streptomycetaceae. In total, five new marine phylotypes, including two within the Thermomonosporaceae that appear to represent new taxa, were obtained in culture. These results support the existence of taxonomically diverse populations of phylogenetically distinct Actinomycetes residing in the marine environment. These bacteria can be readily cultured using low nutrient media and represent an unexplored resource for pharmaceutical drug discovery.

Joy A. Colquhoun – 3rd expert on this subject based on the ideXlab platform

  • Taxonomy and biotransformation activities of some deep-sea Actinomycetes
    Extremophiles, 1998
    Co-Authors: Joy A. Colquhoun, Spencer C. Heald, Lina Li, Jin Tamaoka, Chiaki Kato, Koki Horikoshi, Alan T Bull

    Abstract:

    Deep-sea soft sediments from trench systems and depths in the northwestern Pacific Ocean ranging from less than 300 to 10,897 m in depth have been analyzed for three target genera of Actinomycetes: Micromonospora, Rhodococcus, and Streptomyces. Only culturable strains, recovered at atmospheric pressure on selective isolation media, have been examined to date. Maximum recoveries of culturable bacteria were greater that 10(7)/ml wet g sediment, but Actinomycetes comprised a small proportion of this population (usually less than 1%). The target Actinomycetes were isolated at all depths except from the Mariana Trench sediments. Actinomycete colonies were defined initially on the basis of colony morphologies, and preliminary identification then was made by chemotaxonomic tests. Pyrolysis mass spectrometry (PyMS) of deep-sea mycolic acid-containing Actinomycetes gave excellent correspondence with numerical (phenetic) taxonomic analyses and subsequently was adopted as a rapid procedure for assessing taxonomic diversity. PyMS analysis enabled several clusters of deep-sea rhodococci to be distinguished that are quite distinct from all type strains. 16S rRNA gene sequence analysis has revealed that several of these marine rhodococci have sequences that are very similar to certain terrestrial species of Rhodococcus and to Dietzia. There is evidence for the intrusion of terrestrial runoff into these deep trench systems, and the inconsistency of the phenotypic and molecular taxonomies may reflect recent speciatiion events in Actinomycetes under the high-pressure conditions of the deep sea. The results of DNA-DNA pairing experiments point to the novelty of Rhodococcus strains recovered from hadal depths in the Izu Bonin Trench. Biotransformation studies of deep-sea bacteria have focused on nitrile compounds. Nitrile-metabolizing bacteria, closely related to rhodococci, have been isolated that grow well at low temperature, high salt concentrations, and high pressures, suggesting that they are of marine origin or have adapted to the deep-sea environment.