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PloS One 2016As the major crops in north China, spring crops are usually planted from April through May every spring and harvested in fall. Wheat is also a very common crop...
As the major crops in north China, spring crops are usually planted from April through May every spring and harvested in fall. Wheat is also a very common crop traditionally planted in fall or spring and harvested in summer year by year. This continuous cropping system exhibited the disadvantages of reducing the fertility of soil through decreasing microbial diversity. Thus, management of microbial diversity in the rhizosphere plays a vital role in sustainable crop production. In this study, ten common spring crops in north China were chosen sole-cropped and four were chosen intercropped with peanut in wheat fields after harvest. Denaturing gradient gel electrophoresis (DGGE) and DNA sequencing of one 16S rDNA fragment were used to analyze the bacterial diversity and species identification. DGGE profiles showed the bacterial community diversity in rhizosphere soil samples varied among various crops under different cropping systems, more diverse under intercropping system than under sole-cropping. Some intercropping-specific bands in DGGE profiles suggested that several bacterial species were stimulated by intercropping systems specifically. Furthermore, the identification of these dominant and functional bacteria by DNA sequencing indicated that intercropping systems are more beneficial to improve soil fertility. Compared to intercropping systems, we also observed changes in microbial community of rhizosphere soil under sole-crops. The rhizosphere bacterial community structure in spring crops showed a strong crop species-specific pattern. More importantly, Empedobacter brevis, a typical plant pathogen, was only found in the carrot rhizosphere, suggesting carrot should be sown prudently. In conclusion, our study demonstrated that crop species and cropping systems had significant effects on bacterial community diversity in the rhizosphere soils. We strongly suggest sorghum, glutinous millet and buckwheat could be taken into account as intercropping crops with peanut; while hulled oat, mung bean or foxtail millet could be considered for sowing in wheat fields after harvest in North China.
Topics: Agriculture; Arachis; Bacteria; China; Crops, Agricultural; Denaturing Gradient Gel Electrophoresis; Genetic Variation; Polymerase Chain Reaction; Rhizosphere; Soil Microbiology; Triticum
PubMed: 26934044
DOI: 10.1371/journal.pone.0150618 -
Genome Announcements Apr 2015Empedobacter (formerly Wautersiella) falsenii comb. nov. strain Wf282 was isolated from a cervical neck abscess sample from an 18-year-old female patient. The isolate...
Empedobacter (formerly Wautersiella) falsenii comb. nov. strain Wf282 was isolated from a cervical neck abscess sample from an 18-year-old female patient. The isolate was resistant to many antibiotics, including meropenem and colistin. The total DNA from the multidrug-resistant E. falsenii comb. nov. Wf282 clinical isolate was sequenced.
PubMed: 25838490
DOI: 10.1128/genomeA.00235-15 -
Applied and Environmental Microbiology Apr 2006Legionella pneumophila persists for a long time in aquatic habitats, where the bacteria associate with biofilms and replicate within protozoan predators. While L....
Legionella pneumophila persists for a long time in aquatic habitats, where the bacteria associate with biofilms and replicate within protozoan predators. While L. pneumophila serves as a paradigm for intracellular growth within protozoa, it is less clear whether the bacteria form or replicate within biofilms in the absence of protozoa. In this study, we analyzed surface adherence of and biofilm formation by L. pneumophila in a rich medium that supported axenic replication. Biofilm formation by the virulent L. pneumophila strain JR32 and by clinical and environmental isolates was analyzed by confocal microscopy and crystal violet staining. Strain JR32 formed biofilms on glass surfaces and upright polystyrene wells, as well as on pins of "inverse" microtiter plates, indicating that biofilm formation was not simply due to sedimentation of the bacteria. Biofilm formation by an L. pneumophila fliA mutant lacking the alternative sigma factor sigma(28) was reduced, which demonstrated that bacterial factors are required. Accumulation of biomass coincided with an increase in the optical density at 600 nm and ceased when the bacteria reached the stationary growth phase. L. pneumophila neither grew nor formed biofilms in the inverse system if the medium was exchanged twice a day. However, after addition of Acanthamoeba castellanii, the bacteria proliferated and adhered to surfaces. Sessile (surface-attached) and planktonic (free-swimming) L. pneumophila expressed beta-galactosidase activity to similar extents, and therefore, the observed lack of proliferation of surface-attached bacteria was not due to impaired protein synthesis or metabolic activity. Cocultivation of green fluorescent protein (GFP)- and DsRed-labeled L. pneumophila led to randomly interspersed cells on the substratum and in aggregates, and no sizeable patches of clonally growing bacteria were observed. Our findings indicate that biofilm formation by L. pneumophila in a rich medium is due to growth of planktonic bacteria rather than to growth of sessile bacteria. In agreement with this conclusion, GFP-labeled L. pneumophila initially adhered in a continuous-flow chamber system but detached over time; the detachment correlated with the flow rate, and there was no accumulation of biomass. Under these conditions, L. pneumophila persisted in biofilms formed by Empedobacter breve or Microbacterium sp. but not in biofilms formed by Klebsiella pneumoniae or other environmental bacteria, suggesting that specific interactions between the bacteria modulate adherence.
Topics: Animals; Bacterial Adhesion; Biofilms; Culture Media; Gentian Violet; Legionella pneumophila; Microscopy, Confocal; Plankton; Staining and Labeling
PubMed: 16597995
DOI: 10.1128/AEM.72.4.2885-2895.2006 -
Journal of Global Infectious Diseases Apr 2012
PubMed: 22754253
DOI: 10.4103/0974-777X.96783 -
Journal of Applied Microbiology Mar 1998Eighty-five catalase- and oxidase-positive Gram-negative rods and cocci susceptible to penicillin G were isolated from a variety of food sources. The phenotypic... (Comparative Study)
Comparative Study
Eighty-five catalase- and oxidase-positive Gram-negative rods and cocci susceptible to penicillin G were isolated from a variety of food sources. The phenotypic relationships of these isolates with reference cultures of Bergeyella-like, Chryseobacterium, Empedobacter, Myroides, Moraxella, Sphingobacterium and Weeksella-like strains were examined by numerical taxonomy. Seventy-three isolates were recovered in five groups; 80% of the isolates clustered in groups 1, 2 and 3 and produced indole, bearing a strong resemblance to Weeksella and Bergeyella. They could not, however, be regarded as belonging to the known species of W. virosa and B. zoohelcum. It is suggested that three species may be necessary to accommodate the environmental Weeksella- or Bergeyella-like bacteria. The isolates in groups 4 and 5 had white colonies and were unable to produce indole, in this way resembling the Moraxella genus.
Topics: Bacterial Typing Techniques; Food Microbiology; Gram-Negative Aerobic Rods and Cocci; Gram-Negative Bacteria; Moraxella
PubMed: 9721639
DOI: 10.1046/j.1365-2672.1998.00346.x -
The Journal of Antibiotics Sep 1984Empedopeptin is a new antibiotic produced by empedobacter haloabium nov. sp. (ATCC 31962). It is a water-soluble depsipeptide antibiotic containing eight amino acid...
Empedopeptin is a new antibiotic produced by empedobacter haloabium nov. sp. (ATCC 31962). It is a water-soluble depsipeptide antibiotic containing eight amino acid residues and a C14-fatty acid moiety in the molecule. Although structurally unrelated, empedopeptin and vancomycin have similar antimicrobial spectra against aerobic and anaerobic Gram-positive bacteria including antibiotic-resistant strains. Empedopeptin is highly active in vivo in mice against systemic infections of Staphylococcus aureus, Streptococcus pyogenes and Clostridium perfringens. Empedopeptin is not absorbed orally.
Topics: Animals; Anti-Bacterial Agents; Chemical Phenomena; Chemistry; Flavobacterium; Mice; Microbial Sensitivity Tests; Oligopeptides
PubMed: 6501108
DOI: 10.7164/antibiotics.37.949