Twenty-four endophytic actinomycetes strains were isolated from the Salvia przewalskii in Tibetan Plateau of China by tablet coating method. Fusarium moniliforme, Helminthosporium turcicum and Bipolaris maydis were selected as indicator fungi to test the antimicrobial activities of these endophytic actinomycetes by tablet confrontation method. The results showed that 21 strains can produce antimicrobial substances which accounts for 85.7% of the total separates number. Four strains of endogenous actinomyces have more obvious antifungi activity. According to results of morphology and culture properties and 16S rDNA sequences of endophytic actinomyces, it is concluded that all of the isolates were streptomycetes trains.
Actinomyces ; chemistry ; genetics ; China ; DNA, Ribosomal ; genetics ; Fusarium ; drug effects ; Helminthosporium ; drug effects ; Salvia ; microbiology

Ribosomal engineering is a technique that can improve the biosynthesis of secondary metabolites in the antibiotics-resistant mutants by attacking the bacterial RNA polymerase or ribosome units using the corresponding antibiotics. Ribosomal engineering can be used to discover and increase the production of valuable bioactive secondary metabolites from almost all actinomycetes strains regardless of their genetic accessibility. As a consequence, ribosomal engineering has been widely applied to genome mining and production optimization of secondary metabolites in actinomycetes. To date, more than a dozen of new molecules were discovered and production of approximately 30 secondary metabolites were enhanced using actinomycetes mutant strains generated by ribosomal engineering. This review summarized the mechanism, development, and protocol of ribosomal engineering, highlighting the application of ribosomal engineering in actinomycetes, with the aim to facilitate future development of ribosomal engineering and discovery of actinomycetes secondary metabolites.
Actinobacteria/metabolism* ; Actinomyces/genetics* ; Anti-Bacterial Agents/metabolism* ; Multigene Family ; Ribosomes/genetics*

Pyruvate phosphate dikinase (PPDK; EC 2.7.9.1) is found in certain microorganisms and plants, and catalyzes the conversion of AMP, PPi and phosphoenolpyruvate (PEP) to ATP, Pi and pyruvate. Using the genomic DNA of Microbispora rosea subsp. aerata as the template, a DNA fragment encoding the gene PPDK was amplified by PCR and inserted into the expression vector pET28a(+), yielding pET28a (+)-PPDK. The E. coli BL21 (DE3) was transformed with the pET28a (+)-PPDK. After inducing with IPTG, the E. coli BL21 (DE3) [pET28a (+)-PPDK] expressed recombinant PPDK fused to an N-terminal sequence of 6-His Tag. The molecular weight of PPDK was estimated to be 101 kD by SDS-PAGE. The PPDK was purified by His * Bind Resin affinity chromatography and ultrafiltration using 10 kD cut-off membrane. The successful application of PPDK in pyrosequencing was also demonstrated.
Actinomyces ; enzymology ; Escherichia coli ; genetics ; metabolism ; Pyruvate, Orthophosphate Dikinase ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Recombination, Genetic ; Sequence Analysis

OBJECTIVETo find the development rules of microbial community in rhizoma sphere of the cultivated Atractylodes lancea.

METHODTotal bacteria, fungi and actinomyces were counted by CFU x g(-1) though dilution plate method. And genomic DNA of microbes were extracted and amplified by primers of E. coli's 27f and 1492r to get the 16S rDNA, then the restriction endonuclease Hinf was used to digest the 16S rDNA.

RESULTTotal bacteria, fungi and actinomyces in 2-year old soil were lower than in 1-year old soil, they decreased 46. 14%, 49. 25%, 31.88% respectively and made the ratio of themselves changed. At the same time, all the 8 soil samples got fine 16S rDNA bands, which were about 1500 bp. And the main bands of most of the samples were found at 1000 bp, but the weak bands of each were different although most bands in the same year samples were more similar than in different year ones.

CONCLUSIONIt is indicated that the change of soil microbial community may has some relation to the continous cropping barrier of A. lancea.

Actinomyces ; genetics ; isolation & purification ; Atractylodes ; growth & development ; Bacteria ; genetics ; isolation & purification ; Biodiversity ; Colony Count, Microbial ; DNA, Ribosomal ; genetics ; Fungi ; genetics ; isolation & purification ; Plants, Medicinal ; growth & development ; RNA, Ribosomal, 16S ; genetics ; Rhizome ; growth & development ; Soil Microbiology

OBJECTIVETo establish a systematic method for isolation and identification of aerobic and facultative anaerobic bacteria in the oral cavity.

METHODSSamples of the saliva, dental plaque and periapical granulation tissue were collected from 20 subjects with healthy oral condition and from 8 patients with different oral diseases. The bacteria in the samples were identified by morphological identification, VITEK automatic microorganism identification and 16s rRNA gene sequencing.

RESULTSVITEK automatic microorganism identification and 16s rRNA gene sequencing showed an agreement rate of 22.39% in identifying the bacteria in the samples. We identified altogether 63 bacterial genus (175 species), among which Streptococcus, Actinomyces and Staphylococcus were the most common bacterial genus, and Streptococcus anginosus, Actinomyces oris, Streptococcus mutans and Streptococcus mitis were the most common species. Streptococcus anginosus was commonly found in patients with chronic periapical periodontitis. Streptococcus intermedius and Staphylococcus aureus were common in patients with radiation caries, and in patients with rampant caries, Streptococcus mutans was found at considerably higher rate than other species.

CONCLUSIONAerobic and facultative anaerobic bacteria are commonly found in the oral cavity, and most of them are gram-positive. 16s rRNA gene sequencing is more accurate than VITEK automatic microorganism identification in identifying the bacteria.

Actinomyces ; isolation & purification ; Dental Caries ; Dental Plaque ; microbiology ; Humans ; Mouth ; microbiology ; RNA, Ribosomal, 16S ; genetics ; Saliva ; microbiology ; Staphylococcus aureus ; isolation & purification ; Streptococcus ; isolation & purification

Trans-trans farnesol (tt-farnesol) is a bioactive sesquiterpene alcohol commonly found in propolis (a beehive product) and citrus fruits, which disrupts the ability of Streptococcus mutans (S. mutans) to form virulent biofilms. In this study, we investigated whether tt-farnesol affects cell-membrane function, acid production and/or acid tolerance by planktonic cells and biofilms of S. mutans UA159. Furthermore, the influence of the agent on S. mutans gene expression and ability to form biofilms in the presence of other oral bacteria (Streptococcus oralis (S. oralis) 35037 and Actinomyces naeslundii (A. naeslundii) 12104) was also examined. In general, tt-farnesol (1 mmol x L(-1)) significantly increased the membrane proton permeability and reduced glycolytic activity of S. mutans in the planktonic state and in biofilms (P < 0.05). Moreover, topical applications of 1 mmol x L(-1) tt-farnesol twice daily (1 min exposure/treatment) reduced biomass accumulation and prevented ecological shifts towards S. mutans dominance within mixed-species biofilms after introduction of 1% sucrose. S. oralis (a non-cariogenic organism) became the major species after treatments with tt-farnesol, whereas vehicle-treated biofilms contained mostly S. mutans (>90% of total bacterial population). However, the agent did not affect significantly the expression of S. mutans genes involved in acidogenicity, acid tolerance or polysaccharide synthesis in the treated biofilms. Our data indicate that tt-farnesol may affect the competitiveness of S. mutans in a mixed-species environment by primarily disrupting the membrane function and physiology of this bacterium. This naturally occurring terpenoid could be a potentially useful adjunctive agent to the current anti-biofilm/anti-caries chemotherapeutic strategies.
Actinomyces ; physiology ; Biofilms ; drug effects ; Cell Membrane Permeability ; drug effects ; Colony Count, Microbial ; Durapatite ; Farnesol ; pharmacology ; Gene Expression Regulation, Bacterial ; drug effects ; Glycolysis ; Humans ; Hydrogen-Ion Concentration ; Microbial Viability ; drug effects ; Plankton ; drug effects ; Saliva ; microbiology ; Streptococcus mutans ; drug effects ; genetics ; physiology ; Streptococcus oralis ; physiology