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PubMed2004

Chemical and biological diversity of Bergamot (Citrus bergamia) in relation to environmental factors.

Oil of bergamot is receiving renewed popularity in aromatherapy. The biovariability of Citrus bergamia grown wild in Calabria (Italy) was investigated as far as chemical markers (linalool, linalyl acetate and bergapten) content and antioxidant and antifungal activities of the methanolic extracts. The average content in the markers presents slight variations with the altitude and more evident changes with the latitude of the areas of plant collection.

Antifungal Agents↗
PubMed2006

Preparation of alginate-quaternary ammonium complex beads and evaluation of their antimicrobial activity.

Alginate-quaternary ammonium complex beads with antimicrobial activity were prepared by the reaction of sodium alginate (SA) with 3-(trimethoxysilyl)propyl-octadecyldimethylammonium chloride (TSA) in acid solution, followed by crosslinking with CaCl(2). FTIR spectroscopy analysis showed that the resulting complex was formed mainly through covalent bonds between the hydroxyl groups of SA and the methoxysilyl groups of TSA. The complex beads exhibited a maximum swelling of 20% in water at 37 degrees C and were not hydrolyzed in water during experiments lasting for 30 days. The in vitro antimicrobial activity of the complex beads was evaluated against four species of bacteria and fungi. The test microorganisms were completely eliminated within 20 min when treated with 5% (v/v) complex beads, which showed a wide spectrum of excellent antimicrobial activity. The antimicrobial activity of the complex beads was retained after 10 cycles of washing and drying. The present results indicate that these SA-TSA complex beads are a new type of insoluble cationic polymer that can kill or remove microorganisms in water by mere contact without releasing the reactive agent.

Alginates↗
PubMed2005

Direct colony PCR-SSCP for detection of multiple pythiaceous oomycetes in environmental samples.

Colony PCR was developed for detection of pythiaceous species recovered on selective agar plates without DNA extraction. A minute amount of mycelia from a single colony was picked up with a pipette tip and added directly to the PCR mix as template for DNA amplification. Successful amplification was achieved in over 95% of the colonies recovered from plant tissues, irrigation water and soil with species-specific primers or oomycete ITS-1 primers. PCR was inhibited in the case of colonies emerging from unwashed pine bark potting mix plates. Direct colony PCR with ITS-1 primers combined with single-strand conformation polymorphism analysis (SSCP) was used to determine population levels of single and multiple species in plant and environmental samples. Application of this technique for disease diagnosis and monitoring pathogen sources was explored, and the potential for studying diversity and population dynamics of other cultivated microbial communities in the environment is discussed.

DNA, Fungal↗
PubMed2006

Effect of horticultural waste composting on infected plant residues with pathogenic bacteria and fungi: integrated and localized sanitation.

The aim of this work was to study the effect of composting on the viability of plant pathogenic fungi and bacteria. The research consisted of pilot-scale composting of horticultural waste in compost windrows. Studies were carried out on vegetable residues infected with plant pathogenic microorganisms included by either integrated or localized infection. In the first case, the plant pathogen viability was investigated when infected material was mixed throughout compost, while the localized infection was used to study the effect of the composting process on plant waste spot-inoculated with pathogenic microorganisms. Results for localized sanitation showed the total elimination of all tested phytopathogens between 48 and 120 h after composting began. In this case significant differences were observed in relation to 9 different zones in the pile. The disappearance of these microorganisms was similar when all plant waste included in the windrow was infected (integrated infection). Additionally, the results obtained confirmed that the bacteria showed a greater capacity to persist during composting than the fungi. Composting is therefore considered a useful method for recycling horticultural waste and eliminating phytopathogenic bacteria and fungi that inhabit this kind of residue.

Agriculture↗
PubMed2000

Immuno-capture differential display method (IDDM) for the detection of environmentally induced promoters in rhizobacteria.

A rapid immunological method for trapping and selection of functionally regulated prokaryotic promoters is described. The method is based on application of a novel mini-Tn5 derived promoter probe (pUTTKZY-promoterless lacZY as a reporter and kanamycin resistance) to mutagenise a plant growth promoting fluorescent pseudomonad, Pseudomonas fluorescens 54/96. The transposon allows selection of operon fusion mutants (lacZY(+)) directly on media containing lactose as a sole carbon source as well as selection for kanamycin and lacZ (beta-galactosidase) expression on X-gal indicator media. We have extended the technique to target the surface expression of the induced lactose permease gene (lacY) from mutagenised libraries and the immuno-capture of bacteria with magnetic beads and anti-LacY monospecifc antisera. The benefits of the lacZY reporter are that a library can be rapidly generated and screened in vitro to isolate non-expressed mutants for further in situ screening. Here we demonstrate the development and utility of the technique and its potential as a differential display method for the isolation of promoters that direct regulated gene expression in the phytosphere, or under other imposed conditions.

DNA Transposable Elements↗
PubMed2006

Kutznerides 1-4, depsipeptides from the actinomycete Kutzneria sp. 744 inhabiting mycorrhizal roots of Picea abies seedlings.

Bioassay-guided fractionation of culture supernatants of the actinomycete Kutzneria sp. 744 resulted in the isolation of four new depsipeptides (1-4). Structure analysis revealed the general structure: cyclo[2-(1-methylcyclopropyl)-D-glycine-(2S,3aR,8aS)-6,7-dichloro-3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid-3-hydroxy-D-glutamic acid-O-methyl-L-serine-L-piperazic acid-(S)-2-hydroxy-3,3-dimethylbutanoic acid]. The 3-hydroxy-d-glutamic acid was present as its threo-isomer in 1 and 2 and as its erythro-isomer in 3 and 4. The piperazic acid was modified to its (R)-4-chloro analogue in 2 and to its C-5/N unsaturated analogue in 4. Compounds 1-4 displayed moderate spore germination inhibiting activity against several common root-rotting fungi.

Actinobacteria↗
PubMedDate not supplied

Toxicants from mangrove plants, V. Isolation of the piscicide, 2-hydroxy-5-methoxy-3-undecyl-1,4 benzoquinone (5-O-methylembelin) from Aegiceras corniculatum.

Extracts of the twigs and stems of the mangrove plant Aegiceras corniculatum demonstrated toxicity to fish (Tilapia nilotica). 5-O-Methylembelin was isolated and was shown to be toxic to fish at a concentration of 1 ppm within a period of 75 min. The structure of 5-O-methylembelin was determined by a study of spectroscopic properties and comparison with an authentic synthetic sample.

Animals↗
PubMed1999

A description of cutaneous-subcutaneous pythiosis in fifteen dogs.

Information regarding signalment, duration of clinical signs, history of swimming, results of CBC and serum biochemical analyses, biopsy findings and mycological results, together with treatments and outcome, was retrieved from the medical records of 15 dogs with a diagnosis of pythiosis made between 1985 and 1995 at the Colleges of Veterinary Medicine, North Carolina State University and the University of Florida. Most of the dogs were young (median age 22 months) and represented larger breeds (> 20 kg). Lesions were characteristically chronic, ulcerated, and nodular with multiple draining tracts on the limbs, thoracic wall or perineal regions. The median duration of these lesions was 3 months with a range of 2 weeks-6 months. Seven dogs had a history of swimming. Peripheral eosinophilia was observed in 14 of the dogs. Cytological evaluation of discharge, aspirates, or impression smears made from biopsy specimens revealed hyphae in five of 11 dogs (45%). Histopathological evaluation using the Gomori Methenamine-Silver (GMS) stain was the most useful test for providing presumptive evidence of cutaneous pythiosis. Immunotherapy or antifungal therapy using either amphotericin B, liposomal nystatin, itraconazole, or ketoconazole were all unsuccessful. The only dog to survive underwent amputation of the affected limb; thus, the prognosis for cutaneous pythiosis in the dog is poor.

Animals↗
PubMed2002

Oomycete plant pathogens use electric fields to target roots.

Plant roots generate electrical currents and associated electrical fields as a consequence of electrogenic ion transport at the root surface. Here we demonstrate that the attraction of swimming zoospores of oomycete plant pathogens to plant roots is mediated in part by electrotaxis in natural root-generated electric fields. The zones of accumulation of anode- or cathode-seeking zoospores adjacent to intact and wounded root surfaces correlated with their in vitro electrotactic behavior. Manipulation of the root electrical field was reflected in changes in the pattern of zoospore accumulation and imposed focal electrical fields were capable of overriding endogenous signals at the root surface. The overall pattern of zoospore accumulation around roots was not affected by the presence of amino acids at concentrations expected within the rhizosphere, although higher concentrations induced encystment and reduced root targeting. The data suggest that electrical signals can augment or override chemical ones in mediating short-range tactic responses of oomycete zoospores at root surfaces.

Electricity↗
PubMed2004

Development of negative feedback during successive growth cycles of black cherry.

Negative feedback between plant and soil microbial communities can be a key determinant of vegetation structure and dynamics. Previous research has shown that negative feedback between black cherry (Prunus serotina) and soil pathogens is strongly distance dependent. Here, we investigate the temporal dynamics of negative feedback. To examine short-term changes, we planted successive cycles of seedlings in the same soil. We found that seedling mortality increased steadily with growth cycle when sterile background soil was inoculated with living field soil but not in controls inoculated with sterilized field soil. To examine long-term changes, we quantified negative feedback across successive growth cycles in soil inoculated with living field soil from a mature forest system (more than 70 years old) versus a younger successional site (ca. 25 years old). In both cases negative feedback developed similarly. Our results suggest that negative feedback can develop very quickly in forest systems, at the spatial scale of a single seedling.

Biomass↗
PubMedDate not supplied

Cutaneous pythiosis in horses from Brazil.

Equine pythiosis was studied in five animals from two farms located in a swampy region of southern Brazil (Rio Grande do Sul State). Granulomatous lesions exuding necrotic material and containing a central yellow and firm tissue core, the 'kunker', were observed on the top of the nose of one horse, on the abdomen of two horses and on the hind limbs of two other animals. Direct microscopic preparations, histopathological examination of lesion material, and macroscopic and microscopic characteristics of the isolates confirmed the diagnosis of pythiosis. Surgical intervention of the inflammatory processes, intravenous potassium iodide and topical application of copper sulphate were used without success.

Animals↗
PubMed1990

Pythiosis.

Explore the source record for details and available documents.

Animals↗
PubMed2000

Controlling instability in gacS-gacA regulatory genes during inoculant production of Pseudomonas fluorescens biocontrol strains.

Secondary metabolism in fluorescent pseudomonads is globally regulated by gacS, which encodes a membrane-bound sensor kinase, and gacA, which encodes a transcriptional response regulator. Spontaneous mutation in either gene blocked biosynthesis of the antimicrobial compounds hydrogen cyanide, 2,4-diacetylphloroglucinol, pyoluteorin, and pyrrolnitrin by the model biocontrol strain Pseudomonas fluorescens CHA0. Spontaneous mutants also had altered abilities to utilize several carbon sources and to increase medium pH compared with the wild type, suggesting that gacS and gacA influence primary as well as secondary bacterial metabolism. Inoculant efficacy for biocontrol was significantly reduced by contamination with regulatory mutants which accumulated during inoculum production. Spontaneous mutants accumulated in all 192 separate liquid cultures examined, typically at a frequency of 1% or higher after 12 days. During scale-up in a simulated industrial fermentation process, mutants increased exponentially and accounted for 7, 23, and 61% of the total viable cells after transfer to 20-, 100-, and 500-ml preparations, respectively. GacS(-) and GacA(-) mutants had identical phenotypes and occurred at the same frequency, indicating that the selective pressures for the two mutants were similar. We developed a simple screening method for monitoring inoculant quality based on the distinctive appearance of mutant colonies (i.e., orange color, enlarged diameter, hyperfluorescence). Mutant competitiveness was favored in a nutrient-rich medium with a high electrolyte concentration (nutrient broth containing yeast extract). We were able to control mutant accumulation and to clean up contaminated cultures by using certain mineral amendments (i.e., zinc, copper, cobalt, manganese, and ammonium molybdate) or by diluting media 1/10. Spontaneous mutants and genetic constructs had the same response to culture conditions. Zinc and medium dilution were also effective for improving the genetic stability of other P. fluorescens biocontrol strains obtained from Ghana and Italy.

Bacterial Proteins↗