OBJECTIVE: To study the diversity and bioactivities of cultured actinomycete from feces of Ailuropoda melanoleuca, Equus burchelli and Rhizomys sinensis, and Xylocopa dissimilis body. METHODS: Fresh feces samples of animals' and Xylocopa dissimilis were collected. We used four media to isolate the actinomycete. Strains were identified by phylogenetic analysis of 16S rRNA gene sequences. Hydrolization and enzyme activities of isolates were examined. RESULTS: Actinomycetes (121) from the samples were isolated on four media. Among them 47 strains belonged to 9 actinomycetes genera. Six known rare genera and one possible new genus of actinomyctes from Rhizomys sinensis were identified. Three possible new species from other three samples were identified. Some strains could hydrolyze chicken feather and cellulose. CONCLUSION: It is considered that the coprophilous microorganisms not only have important function on the digestion and absorption of animal feed, but also are important resource for development of industrial products, including enzyme and bioactive metabolites.

The frequent discrepancy between direct microscopic counts and numbers of culturable bacteria from environmental samples is just one of several indications that we currently know only a minor part of the diversity of microorganisms in nature. A combination of direct retrieval of rRNA sequences and whole-cell oligonucleotide probing can be used to detect specific rRNA sequences of uncultured bacteria in natural samples and to microscopically identify individual cells. Studies have been performed with microbial assemblages of various complexities ranging from simple two-component bacterial endosymbiotic associations to multispecies enrichments containing magnetotactic bacteria to highly complex marine and soil communities. Phylogenetic analysis of the retrieved rRNA sequence of an uncultured microorganism reveals its closest culturable relatives and may, together with information on the physicochemical conditions of its natural habitat, facilitate more directed cultivation attempts. For the analysis of complex communities such as multispecies biofilms and activated-sludge flocs, a different approach has proven advantageous. Sets of probes specific to different taxonomic levels are applied consecutively beginning with the more general and ending with the more specific (a hierarchical top-to-bottom approach), thereby generating increasingly precise information on the structure of the community. Not only do rRNA-targeted whole-cell hybridizations yield data on cell morphology, specific cell counts, and in situ distributions of defined phylogenetic groups, but also the strength of the hybridization signal reflects the cellular rRNA content of individual cells. From the signal strength conferred by a specific probe, in situ growth rates and activities of individual cells might be estimated for known species. In many ecosystems, low cellular rRNA content and/or limited cell permeability, combined with background fluorescence, hinders in situ identification of autochthonous populations. Approaches to circumvent these problems are discussed in detail.

A set of oligonucleotide primers capable of initiating enzymatic amplification (polymerase chain reaction) on a phylogenetically and taxonomically wide range of bacteria is described along with methods for their use and examples. One pair of primers is capable of amplifying nearly full-length 16S ribosomal DNA (rDNA) from many bacterial genera; the additional primers are useful for various exceptional sequences. Methods for purification of amplified material, direct sequencing, cloning, sequencing, and transcription are outlined. An obligate intracellular parasite of bovine erythrocytes, Anaplasma marginale, is used as an example; its 16S rDNA was amplified, cloned, sequenced, and phylogenetically placed. Anaplasmas are related to the genera Rickettsia and Ehrlichia. In addition, 16S rDNAs from several species were readily amplified from material found in lyophilized ampoules from the American Type Culture Collection. By use of this method, the phylogenetic study of extremely fastidious or highly pathogenic bacterial species can be carried out without the need to culture them. In theory, any gene segment for which polymerase chain reaction primer design is possible can be derived from a readily obtainable lyophilized bacterial culture.

After nearly 10 years of PCR-based analysis of prokaryotic small-subunit ribosomal RNAs for ecological studies it seems necessary to summarize reported pitfalls of this approach which will most likely lead to an erroneous description on the microbial diversity of a given habitat. The following article will cover specific aspects of sample collection, cell lysis, nucleic acid extraction, PCR amplification, separation of amplified DNA, application of nucleic probes and data analysis.

The PCR is used widely for the study of rRNA genes amplified from mixed microbial populations. These studies resemble quantitative applications of PCR in that the templates are mixtures of homologs and the relative abundance of amplicons is thought to provide some measure of the gene ratios in the starting mixture. Although such studies have established the presence of novel rRNA genes in many natural ecosystems, inferences about gene abundance have been limited by uncertainties about the relative efficiency of gene amplification in the PCR. To address this question, three rRNA gene standards were prepared by PCR, mixed in known proportions, and amplified a second time by using primer pairs in which one primer was labeled with a fluorescent nucleotide derivative. The PCR products were digested with restriction endonucleases, and the frequencies of genes in the products were determined by electrophoresis on an Applied Biosystems 373A automated DNA sequencer in Genescan mode. Mixtures of two templates amplified with the 519F-1406R primer pair yielded products in the predicted proportions. A second primer pair (27F-338R) resulted in strong bias towards 1:1 mixtures of genes in final products, regardless of the initial proportions of the templates. This bias was strongly dependent on the number of cycles of replication. The results fit a kinetic model in which the reannealing of genes progressively inhibits the formation of template-primer hybrids.

Using a set of synthetic oligonucleotides homologous to broadly conserved sequences in-vitro amplification via the polymerase chain reaction followed by direct sequencing results in almost complete nucleotide determination of a gene coding for 16S ribosomal RNA. As a model system the nucleotide sequence of the 16S rRNA gene of M.kansasii was determined and found to be 98.7% homologous to that of M.bovis BCG. This is the first report on a contiguous sequence information of an entire amplified gene spanning 1.5 kb without any subcloning procedures.

BACKGROUND: Comparative analysis of RNA sequences is the basis for the detailed and accurate predictions of RNA structure and the determination of phylogenetic relationships for organisms that span the entire phylogenetic tree. Underlying these accomplishments are very large, well-organized, and processed collections of RNA sequences. This data, starting with the sequences organized into a database management system and aligned to reveal their higher-order structure, and patterns of conservation and variation for organisms that span the phylogenetic tree, has been collected and analyzed. This type of information can be fundamental for and have an influence on the study of phylogenetic relationships, RNA structure, and the melding of these two fields. RESULTS: We have prepared a large web site that disseminates our comparative sequence and structure models and data. The four major types of comparative information and systems available for the three ribosomal RNAs (5S, 16S, and 23S rRNA), transfer RNA (tRNA), and two of the catalytic intron RNAs (group I and group II) are:(1) Current Comparative Structure Models;(2) Nucleotide Frequency and Conservation Information;(3) Sequence and Structure Data; and (4) Data Access Systems. CONCLUSIONS: This online RNA sequence and structure information, the result of extensive analysis, interpretation, data collection, and computer program and web development, is accessible at our Comparative RNA Web (CRW) Site http://www.rna.icmb.utexas.edu. In the future, more data and information will be added to these existing categories, new categories will be developed, and additional RNAs will be studied and presented at the CRW Site.

The 16S rRNA gene sequences of 34 named and unnamed clostridial strains were determined by PCR direct sequencing and were compared with more than 80 previously determined clostridial sequences and the previously published sequences of representative species of other low- G + C-content gram-positive genera, thereby providing an almost complete picture of the genealogical interrelationships of the clostridia. The results of our phylogenetic analysis corroborate and extend previous findings in showing that the genus Clostridium is extremely heterogeneous, with many species phylogenetically intermixed with other spore-forming and non-spore-forming genera. The genus Clostridium is clearly in need of major revision, and the rRNA structures defined in this and previous studies may provide a sound basis for future taxonomic restructuring. The problems and different possibilities for restructuring are discussed in light of the phenotypic and phylogenetic data, and a possible hierarchical structure for the clostridia and their close relatives is presented. On the basis of phenotypic criteria and the results of phylogenetic analyses the following five new genera and 11 new combinations are proposed: Caloramator gen. nov., with Caloramator fervidus comb. nov.; Filifactor gen. nov., with Filifactor villosus comb. nov.; Moorella gen. nov., with Moorella thermoacetica comb. nov. and Moorella thermoautotrophica comb. nov.; Oxobacter gen. nov., with Oxobacter pfennigii comb. nov.; Oxalophagus gen. nov., with Oxalophagus oxalicus comb. nov.; Eubacterium barkeri comb. nov.; Paenibacillus durum comb. nov.; Thermoanaerobacter kivui comb. nov.; Thermoanaerobacter thermocopriae comb. nov.; and Thermoanerobacterium thermosaccharolyticum comb. nov.

The genus Nocardiopsis was shown to be phylogenetically coherent and to represent a distinct lineage within the radiation of the order Actinomycetales. The closest relatives of the genus Nocardiopsis are members of the genera Actinomadura, Thermomonospora, Streptosporangium, and Microtetraspora. The intrageneric structure of the genus Nocardiopsis is shown to consist of a highly related species group containing Nocardiopsis dassonvillei, Nocardiopsis alborubida, and Nocardiopsis antarctica and a second group of less highly related species comprising Nocardiopsis alba subsp. alba, Nocardiopsis alba subsp. prasina, and Nocardiopsis listeri. Nocardiopsis lucentensis occupies a position intermediate between the two species groups. The results of a 16S ribosomal DNA sequence analysis are generally consistent with the available chemotaxonomic, phenotypic, and DNA-DNA hybridization data. The phylogenetic position and the morpho- and chemotaxonomic properties of Nocardiopsis species support the creation of a family for the genus Nocardiopsis, Nocardiopsaceae fam. nov.

Three 16S rRNA hybridization probes were developed and tested for genus-specific detection of Bifidobacterium species in the human fecal flora. Variable regions V2, V4, and V8 of the 16S rRNA contained sequences unique to this genus and proved applicable as target sites for oligodeoxynucleotide probes. Determination of the genus specificity of the oligonucleotides was performed by whole-cell hybridization with fluorescein isothiocyanate-labelled probes. To this end, cells were fixed on glass slides, hybridized with the probes, and monitored by videomicroscopy. In combination with image analysis, this allowed quantification of the fluorescence per cell and objective evaluation of hybridization experiments. One of the probes developed was used to determine the population of Bifidobacterium spp. in human fecal samples. A comparison was made with results obtained by cultural methods for enumeration. Since both methods gave similar population estimates, it was concluded that all bifidobacteria in feces were culturable. However, since the total culturable counts were only a fraction of the total microscopic counts, the contribution of bifidobacteria to the total intestinal microflora was overestimated by almost 10-fold when cultural methods were used as the sole method for enumeration.