RSS 1.0This is the institutional Repository of the Helmholtz Centre for Infection Research in Braunschweig/Germany (HZI), the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarbrücken/Germany, the TWINCORE Zentrum für Exprerimentelle und Klinische Infektionsforschung, Hannover/Germany,Helmholtz-Institut für RNA-basierte Infektionsforschung (HIRI), Würzburg/Germany, Braunschweig Integrated Centre for Systems biology (BRICS), Centre for Structural Systems Biology (CSSB) the Study Centre Hannover, Hannover/Germany and the Centre for Individualised Infection Medicine (CiiM).
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IMPROVEMENTS IN THE TAXONOMY OF FLAVOBACTERIUM BY DNA:rRNA HYBRIDIZATIONSDNA:rRNA hybridizations revealed the considerable heterogeneity of named flavobacteria. Low % GC Flavobacterium aquatile, F. pectinovorum, F. tirrenicum, F. uliginosum, F. odoratum, F. breve, F. meningosepticum and several named Cytophaga species form a large, heterogeneous cluster. Several other Flavobacterium species are misnamed and belong in entirely different taxa.
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EMENDATION OF THE GENUS FLAVOBACTERIUM AND THE STATUS OF THE GENUS. DEVELOPMENTS AFTER THE 8TH EDITION OF BERGEY'S MANUALIn the 8th edition of Bergey's Manual [25] the genus Flavobacterium remained taxonomically heterogeneous, being divided into two sections. Section I contained six non-motile species with the G+C content of their DNA in the range 30 to 42 mol % (low G+C content strains) and Section II contained six species that were either nonmotile or motile and peritrichous but with G+C contents in the range 63 to 70 mol % (high G+C content strains). Here we describe the general background and sequence of events, culminating in an emended description of the genus [12], in which restriction of Flavobacterium to certain well-described low G+C content species is proposed. The reasons for replacing the current type species F. aquatile, with F. breve will also be discussed. Although only four species conform to the emended description of Flavobacterium at present, other taxa that are candidates for inclusion in the genus will be described as well as the taxonomic problems associated with them; particular reference will be made to Flavobacterium Group IIb [23]. The taxonomic status of the high G+C content strains of Section II will be discussed as will the status of certain taxa, such as Group IIf [23], which are sometimes referred to as Flavobacterium-like.
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A SURVEY OF FLAVOBACTERIUMThe survey of Flavobacterium is a general review of the origins of the genus and of its taxonomic development in the various editions of Bergey's Manual. Brief consideration is given to the chemistry of the pigments which have been studied.
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THE CLASSIFICATION OF THE CYTOPHAGA-LIKE BACTERIABased on a thorough study of a considerable number of strains, most of them newly isolated, we believe that the taxonomy of the cytophagas and related organisms has to be reconstructed from its very base. Using GC and DNA-DNA hybridization data as well as chemosystematic, physiological, biochemical and morphological observations, the following groups can be recognized with some confidence: Sporocytophaga, Flexibacter (in the original sense), Lysobacter, and Sphaerocytophaga/Capnocytophaga. The remaining bulk of strains, classified now as Cytophaga/Flexibacter (the latter in a sense deviating from the original definition) comprises with certainty several different genera, and the genus Cytophaga s. str. may finally have to be restricted again to aerobic cellulose-decomposing soil organisms. With the exception of a few rare cases, our present knowledge does not allow us to reliably distinguish between species.
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Title - Foreword - Contents - List of AuthorsThe two bacterial genera, Cytophaga and Flavobacterium, account for many of the yellow or orange pigmented, gram-negative bacteria which we isolate from natural and man-made environments. However, their taxonomy is far from being clear. This is very unsatisfactory, particularly as many of these bacteria are of considerable practical importance, appearing quite regularly in the clinical laboratory, or playing a role as spoilage organisms in the food industry, as fish-pathogens, or as producers of interesting enzymes and antibiotics. Last but not least, enormous populations of these organisms live in soil, freshwater, and marine environments, and are undoubtedly greatly involved in the degradation and turnover of organic substrates in nature, as well as in sewage plants. Both "genera" comprise rod-shaped, heterotrophic, primarily aerobic bacteria, which, in the case of the cytophagas move by gliding, while the flavobacteria are either immotile or flagellated. As a result of the research of the past 15 years we can today be sure that both groups are taxonomically heterogeneous. Somewhat unexpectedly, observations came to the light which suggested connections, perhaps even relatively close ones, between some of the flavobacteria with a low DNA base ratio (30 to 40 mol % GtC) and respective Cytophaga-like bacteria (CLB). This meeting has been organized by us, together with Dr. D. Claus from the DSM (German Collection of Microorganisms) in Gdttingen to discuss these new developments. Some of the more impressive data which would indicate a relationship between flavobacteria and CLB are presented in this volume, e.g. studies on the distribution among these organisms of lipoquinones, hydroxy fatty acids, and flexirubin-type pigments. Reports on unusual cellular constituents, like sphingolipids or sulfonolipids, in some of these bacteria should stimulate investigation into the occurrence of such compounds in other representatives of this group and might provide valuable additional indications of a relationship. Of course, further problems still remain to be solved. Thus, it is not yet apparent how the new genera, Cytophaga and Flavobacterium, should be delimitated and defined, nor how to proceed with the remaining organisms, e.g. the "flavobacteria" with a high G+C content (60 to 70 mol %). As can be seen from the contributions of this symposium, lively discussions ‘take place about such questions, but there is neither universal agreement yet, nor are there always sufficient available data to enable the taxonomic problems to be dealt with competently. There are actually large areas in the taxonomy of flavobacteria and CLB, where we are still only at the start. Modern taxonomic methods, like those offered by molecular biology, or the chemosystematic approach, as applied more recently to this difficult group of bacteria, promise progress in the near future. It is our opinion that this symposium has provided a good survey of the state of the taxonomy of flavobacteria and CLB, and we hope that it will stimulate further research. We should like to take the opportunity to thank all those persons who helped to make this symposium possible. The directors of the GBF, Prof. Dr. K. Kieslich and Dr. H. Zeitträger, were in favor of our enterprise from the very beginning, and allowed us to use the lecture room as well as the facilities of the institute. They also gave us essential financial support. R. Radloff solved most of the organizational problems, and Karin Rahn typed many letters in connection with the symposium and had much work with the articles for this proceedings volume. Dr. J.H. Walsdorff gave valuable assistance in compiling and editing this volume.
