A total of 445 actinomycete isolates were obtained from 16 medicinal plant rhizosphere soils. Morphological and chemotaxonomic studies indicated that 89% of the isolates belonged to the genus Streptomyces, 11% were non-Streptomycetes: Actinomadura sp., Microbispora sp., Micromonospora sp., Nocardia sp, Nonomurea sp. and three isolates were unclassified. The highest number and diversity of actinomycetes were isolated from Curcuma mangga rhizosphere soil. Twenty-three Streptomyces isolates showed activity against at least one of the five phytopathogenic fungi: Alternaria brassicicola, Collectotrichum gloeosporioides, Fusarium oxysporum, Penicillium digitatum and Sclerotiumrolfsii. Thirty-six actinomycete isolates showed abilities to produce indole-3-acetic acid (IAA) and 75 isolates produced siderophores on chrome azurol S (CAS) agar. Streptomyces CMU-PA101 and Streptomyces CMU-SK126 had high ability to produced antifungal compounds, IAA and siderophores.

Actinomycetes isolated from medicinal plant rhizosphere soils: diversity and screening of antifungal compounds, indole-3-acetic acid and siderophore production

New structurally diverse natural products are discovered when novel screening procedures are introduced or when high quality biological materials from new sources are examined in existing screens, hence it is important to foster these two aspects of novelty in drug discovery programmes. Amongst prokaryotes, actinomycetes, notably streptomycetes, remain a rich source of new natural products though it has become increasingly difficult to find such metabolites from common actinomycetes as screening ‘old friends’ leads to the costly rediscovery of known compounds. The bioprospecting strategy which is the subject of this review is based upon the premise that new secondary metabolites can be found by screening relatively small numbers of dereplicated, novel actinomycetes isolated from marine sediments. The success of the strategy is exemplified by the discovery of a range of novel bioactive compounds, notably atrop-abyssomicin C and proximicins A, B and C from Verrucosispora strains isolated from sediment samples taken from the Sea of Japan and the Raune Fjord, respectively, and the dermacozines derived from Dermacoccus strains isolated from the Challenger Deep of the Mariana Trench in the Pacific Ocean. The importance of current advances in prokaryotic systematics in work of this nature is stressed and a plea made that resources be sought to train, support and employ the next generation of actinobacterial systematists.

A guide to successful bioprospecting: Informed by actinobacterial systematics

The purpose of this announcement is to effect the valid publication of the following new names and new combinations under the procedure described in the Bacteriological Code (1990 Revision). Authors and other individuals wishing to have new names and/or combinations included in future lists should send three copies of the pertinent reprint or photocopies thereof to the IJSEM Editorial Office for confirmation that all of the other requirements for valid publication have been met. It is also a requirement of IJSEM and the ICSP that authors of new species, new subspecies and new combinations provide evidence that types are deposited in two recognized culture collections in two different countries (i.e. documents certifying deposition and availability of type strains). It should be noted that the date of valid publication of these new names and combinations is the date of publication of this list, not the date of the original publication of the names and combinations. The authors of the new names and combinations are as given below, and these authors' names will be included in the author index of the present issue and in the volume author index. Inclusion of a name on these lists validates the publication of the name and thereby makes it available in bacteriological nomenclature. The inclusion of a name on this list is not to be construed as taxonomic acceptance of the taxon to which the name is applied. Indeed, some of these names may, in time, be shown to be synonyms, or the organisms may be transferred to another genus, thus necessitating the creation of a new combination.

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Validation of publication of new names and new combinations previously effectively published outside the IJSEM

Reports describing actinobacteria isolated from marine environments have been dominated by Micromonospora, Rhodococcus and Streptomyces species. Recent culture-independent studies have shown that marine environments contain a high diversity of actinobacterial species that are rarely, if at all, recovered by cultivation-based methods. In this study, it is shown that cultivation-independent methods can be used to guide the application of selective isolation methods. The detection of marine-derived actinobacterial species that have previously only been reported from terrestrial habitats is highlighted. This study provides good evidence that the previously described low diversity of actinobacterial species isolated from marine environments does not reflect an actual low species diversity, and that the use of informed selective isolation procedures can aid in the isolation of members of novel taxa.

Diversity of cultivable actinobacteria in geographically widespread marine sediments

The Atacama Desert presents one of the most extreme environments on Earth and we report here the first extensive isolations of actinomycetes from soils at various locations within the Desert. The use of selective isolation procedures enabled actinomycetes to be recovered from arid, hyper-arid and even extreme hyper-arid environments in significant numbers and diversity. In some cases actinomycetes were the only culturable bacteria to be isolated under the conditions of this study. Phylogenetic analysis and some phenotypic characterisation revealed that the majority of isolates belonged to members of the genera Amycolatopsis, Lechevalieria and Streptomyces, a high proportion of which represent novel centres of taxonomic variation. The results of this study support the view that arid desert soils constitute a largely unexplored repository of novel bacteria, while the high incidence of non-ribosomal peptide synthase genes in our isolates recommend them as promising material in screening for new bioactive natural products.

Diversity of culturable actinomycetes in hyper-arid soils of the Atacama Desert, Chile.

Large numbers of putatively novel streptomycetes were isolated from environmental samples collected from in and around the root system of the tropical angiosperm, Paraserianthes falcataria. Representative isolates were assigned to 37 multi-membered and 107 single membered colour groups based on their ability to form pigments on oatmeal and peptone yeast extract iron agars. The largest taxon, colour group 3, encompassed 94 isolates which had morphological properties typical of members of the Streptomyces violaceusniger clade. Twelve representatives of this taxon chosen on the basis of Curie-point pyrolysis mass spectrometric data were compared with representatives of the validly described species which constitute the Streptomyces violaceusniger clade. Six out of the twelve representative strains were readily distinguished from one another and from the marker strains using a combination of genotypic and phenotypic properties. These organisms were consequently considered to merit species status as Streptomyces asiaticus sp. nov., Streptomyces cangkringensis sp. nov., Streptomyces indonesiensis sp. nov., Streptomyces javensis sp. nov., Streptomyces rhizosphaerius sp. nov. and Streptomyces yogyakartensis sp. nov.

Selective isolation and characterisation of members of the Streptomyces violaceusniger clade associated with the roots of Paraserianthes falcataria.

The taxonomic position of an actinomycete isolated from an ultramafic soil in New Caledonia was examined using a polyphasic approach. The organism, which was designated SFOCin 76, was found to have chemical and morphological properties typical of streptomycetes and formed a distinct phyletic line in the Streptomyces violaceusniger clade of the 16S rDNA tree. It also showed a unique pattern of phenotypic properties that distinguished it from representatives of all of the validly described species classified in this clade. It is, therefore, proposed that strain SFOCin 76 be classified in the genus Streptomyces as Streptomyces yatensis sp. nov.

Streptomyces yatensis sp. nov., a novel bioactive streptomycete isolated from a New-Caledonian ultramafic soil.

Search and discovery for natural bioactive products have been so important to control the emergence of antibiotic resistant microbial pathogens. Therefore, novel microorganisms that produce such metabolites is extremely needed. The capacity of members of the genus Streptomyces to produce commercially significant bioactive metabolites, notably antibiotics remains unsurpassed. However, it is acknowledged that discovering commercially useful secondary metabolites from streptomycetes is becoming more difficult due to lack of knowledge on the ecology and complexity of streptomycete systematics. In fact, those are fundamental aspects for developing strategy and method for isolation. In order to devise an appropriate program for successful selective isolation of sreptomycetes, it is fundamentally important to understand their occurance and activity in nature. A multistep extraction procedure designed for representative sampling, called dispersion, and differential centrifugation technique in combination with the incorporation of antibiotics into isolation media has become one of the most important selective method for the isolation of streptomycetes from natural habitats. The availability of new procedures to selectively isolate representative of streptomycetes from natural habitats opens up the possibility to determine the extent of streptomycete diversity from various habitats. Hence, the capacity of well characterized streptomycete isolates to produce commercial novel active metabolites could be further assessed appropriately.

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Ecological Approach to Unravel Streptomycete Diversity as an Unsurpassed Sources of Natural Bioactive Products

Systematics plays an important role in the utilization of streptomycete strains as an outstanding producer of thousands documented bioactive compounds. The chaotic state of streptomycete systematics resulted from the application of traditional monothetic approach had clearly hampered the progress of development of reliable identification system for potential streptomycete strains. However, the extensive application of polythetic numerical method by increasing number of experts was proved to be successful in developing a more sounding streptomycete classification system. As a consequence, such classification system can subsequently be used as a rigorous basis to generate a more reliable identification system in attempt to unravel the extent of streptomycete diversity in natural habitats both at the inter and intraspecies level. This review addresses the problem and the role of numerical systematics in the development of current status of streptomycete systematics which is applicable to delimit species within the genus. Key words: streptomycete systematics, monothetic, polythetic, streptomycete diversity

Langkah Sembiring

Papers

Selective isolation and characterisation of members of the Streptomyces violaceusniger clade associated with the roots of Paraserianthes falcataria.

Streptomyces yatensis sp. nov., a novel bioactive streptomycete isolated from a New-Caledonian ultramafic soil.

Ecological Approach to Unravel Streptomycete Diversity as an Unsurpassed Sources of Natural Bioactive Products

Application of Numerical Systematics in Unraveling Streptomycete Diversity