共查询到20条相似文献,搜索用时 31 毫秒
1.
Allelopathy of the eucalypt has been considered as an important mechanism for the biodiversity reduction in the eucalypt plantation.
To understand the allelopathic potential of the eucalypt (Eucalyptus grandis) roots and rhizosphere soil along a chronosequence (2, 4, 6, 8, 10 years), the germination and growth characteristics of
three plant species (Raphanus sativus, Phaseolus aureus, and Lolium perenne) growing nearby or beneath the eucalypt plantations were measured. The results showed that aqueous extract of E. grandis root suppressed the germination and early seedling growth of the target plants. The younger E. grandis exhibited a comparatively stronger allelopathic potential. The highest dose root extracts from 4 years old E. grandis showed the strongest inhibitory effects on the germination rates of the target species, the inhibitory rates were about 48,
51.2, and 56.56% for R. sativus, P. aureus, and L. perenne, respectively. However, present biotests of rhizosphere soils from 6, 8, and 10-year-old plantations exhibited a remarkable
stimulative effect on L. perenne, which indicated that the soil might neutralize or dilute allelopathic agents with the increase of plantation age. In addition,
according to GC–MS analysis, more allelopathic potential compounds were found in the rhizosphere soil and roots of younger
E. grandis plantation. Moreover, more allelochemicals were obtained from soil than from roots. The allelopathic compounds in roots
and rhizosphere soil may play important roles in allelopathy of E. grandis plantation. More attention should be paid to the younger E. grandis plantations for the relative higher allelopathic effects. 相似文献
2.
This is the first report on the ascomycete Metschnikowia typographi from the adults and larvae of the great spruce bark beetle Dendroctonus micans in Turkey. In total, 910 of 1928 adults and 44 of 149 larvae investigated during the two years were infected by the pathogen.
In a fresh smear the asci of the pathogen measure 18.5 ± 2.05 μm (14.7–22.3) in length and 2.1 ± 0.4 μm in width (n = 35). The ascospores are about 2 μm shorter than asci, having an average length of 16.4 ± 1.5 μm (14.2–18.0). The total
infection rate of D. micans was 47.2 %. The prevalence of M. typographi infections differed between localities and years. Different infection rates of male and female beetles of D. micans were not recognized. 相似文献
3.
A pea rust fungus, Uromyces viciae-fabae, has been classified into two varieties, var. viciae-fabae and var. orobi, based on differences in urediniospore wall thickness and putative host specificity in Japan. In principal component analyses, morphological features of urediniospores and teliospores of 94 rust specimens from Vicia, Lathyrus, and Pisum did not show definite host-specific morphological groups. In molecular analyses, 23 Uromyces specimens from Vicia, Lathyrus, and Pisum formed a single genetic clade based on D1/D2 and ITS regions. Four isolates of U. viciae-fabae from V. cracca and V. unijuga could infect and sporulate on P. sativum. These results suggest that U. viciae-fabae populations on different host plants are not biologically differentiated into groups that can be recognized as varieties.Contribution no. 184, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan 相似文献
4.
Endophytic fungi are rich in orchids and have great impacts on their host plants. 53 endophytes (30 isolates from Dendrobium devonianum and 23 endophytic fungi from D. thyrsiflorum) were isolated, respectively, from roots and stems of Dendrobium species. All the fungi were identified by way of morphological and/or molecular biological methods. 30 endophytic fungi in
D. devonianum were categorized into 11 taxa and 23 fungal endophytes in D. thyrsiflorum were grouped into 11 genera, respectively. Fusarium was the dominant species of the two Dendrobium species in common. Antimicrobial activity of ethanol extract of fermentation broth of these fungi was explored using agar
diffusion test. 10 endophytic fungi in D. devonianum and 11 in D. thyrsiflorum exhibited antimicrobial activity against at least one pathogenic bacterium or fungus among 6 pathogenic microbes (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus). Out of the fungal endophytes isolated from D. devonianum and D. thyrsiflorum, Phoma displayed strong inhibitory activity (inhibition zones in diameter >20 mm) against pathogens. Epicoccum nigrum from D. thyrsiflorum exhibited antibacterial activity even stronger than ampicillin sodium. Fusarium isolated from the two Dendrobium species was effective against the pathogenic bacterial as well as fungal pathogens. The study reinforced the assumption that
endophytic fungi isolated from different Dendrobium species could be of potential antibacterial or antifungal resource. 相似文献
5.
6.
A peptide antibiotic, gramicidin A, was covalently bound to cystamine self-assembled monolayers on gold surfaces. Each step
of the surface functionalization was characterized by polarization modulation infrared reflection absorption spectroscopy
and X-ray photoelectron spectroscopy. The antimicrobial activity of the anchored gramicidin was tested against three Gram-positive
bacteria (Listeria ivanovii, Enterococcus faecalis, and Staphylococcus aureus), the Gram-negative bacterium Escherichia coli and the yeast Candida albicans. The results revealed that the adsorbed gramicidin reduced, from 60% for E. coli to 90% for C. albicans, the number of culturable microorganisms attached to the surface. The activity was proven to be persistent overtime, up to
6 months after the first use. The bacteria attached to the functionalized surfaces were permeabilized as shown by confocal
microscopy. Taken together, these results indicate a bacteriostatic mode of action of the immobilized peptide. Finally, using
green fluorescent protein-expressing bacteria, it was shown that the development of a bacterial biofilm was delayed on peptide-grafted
surfaces for at least 24 h. 相似文献
7.
Roberts DP McKenna LF Hu X Lohrke SM Kong HS de Souza JT Baker CJ Lydon J 《Archives of microbiology》2007,187(2):101-115
Strains of Enterobacter cloacae show promise as biological control agents for Pythium ultimum-induced damping-off on cucumber and other crops. Enterobacter cloacae M59 is a mini-Tn5 Km transposon mutant of strain 501R3. Populations of M59 were significantly lower on cucumber roots and decreased much more
rapidly than those of strain 501R3 with increasing distance from the soil line. Strain M59 was decreased or deficient in growth
and chemotaxis on most individual compounds detected in cucumber root exudate and on a synthetic cucumber root exudate medium.
Strain M59 was also slightly less acid resistant than strain 501R3. Molecular characterization of strain M59 demonstrated
that mini-Tn5 Km was inserted in cyaA, which encodes adenylate cyclase. Adenylate cyclase catalyzes the formation of cAMP and cAMP levels in cell lysates from
strain M59 were approximately 2% those of strain 501R3. Addition of exogenous, nonphysiological concentrations of cAMP to
strain M59 restored growth (1 mM) and chemotaxis (5 mM) on synthetic cucumber root exudate and increased cucumber seedling
colonization (5 mM) by this strain without serving as a source of reduced carbon, nitrogen, or phosphorous. These results
demonstrate a role for cyaA in colonization of cucumber roots by Enterobacter cloacae. 相似文献
8.
Fernanda Laroza Paganelli Eliana Gertrudes de Macedo Lemos Lúcia Maria Carareto Alves 《World journal of microbiology & biotechnology》2011,27(4):773-778
Polyhydroxyalkanoates (PHAs) are hydroxyalkanoate polymers that are produced and accumulate by many kinds of bacteria. These
polymers act as an energy store for bacteria. Polyhydroxybutyrate (PHB) is the most studied polymer in the PHA family. These
polymers have awakened interest in the environmental and industrial research areas because they are biodegradable and have
thermoplastic qualities, like polypropylene. In this work, we analyzed the PHB production in Bradyrhizobium sp., Rhizobium leguminosarum bv. phaseoli, and Rhizobium huautlense cultured with two different carbon sources. We did biochemical quantification of PHB production during the three phases of
growth. Moreover, these samples were used for RNA extraction and phbC gene expression analysis via real-time PCR. The bacteria showed different manner of growth, PHB accumulation and phbC gene expression when different quantity and quality of carbon sources were used. These results showed that under different
growth media conditions, the growth and metabolism of different species of bacteria were influenced. These differences reflect
the increase or decrease in PHB accumulation. 相似文献
9.
Karolina Vrandecic Drazenka Jurkovic Luca Riccioni Jasenka Cosic Tomislav Duvnjak 《Mycopathologia》2010,170(1):51-60
Sunflower (Helianthus annuus) stem canker caused by Diaporthe helianthi is one of the most important sunflower diseases in Croatia. Until recently, sunflower was the only known host for D. helianthi. In our research carried out in the area of Eastern Croatia, isolates of Diaporthe/Phomospis were collected from Xanthium italicum, X. strumarium and Arctium lappa. Using morphological, cultural and molecular ITS rDNA data, isolates from these weeds were identified as D. helianthi. The following isolates were used in the pathogenicity test: one isolate originated from sunflower (Su5/04), three from X. italicum (Xa2, Xa3 and Xa5), two from X. strumarium (Xa9 and Xa12), one from Xanthium sp. (Xa13) and one from A. lappa (Ar3). According to the results, it was determined that isolate Xa5 (originated from X. italicum) was the most pathogenic to sunflower stems. The average length of the lesion was 11.3 cm. The lowest level of pathogenicity
was found in Xa9 (isolated from X. strumarium). The length of the lesion was 0.1 cm. 相似文献
10.
Ticks of the genus Dermacentor are important vectors of human and animal pathogens in North America. They also carry a variety of endosymbiotic (i.e. non-pathogenic)
bacteria. The American dog tick, D.
variabilis, is known to be infected with gammaproteobacteria of the genus Arsenophonus. However, there have been no previous reports of Arsenophonus-type bacteria in the Rocky Mountain wood tick, D. andersoni, a species that is sympatric with D. variabilis in the western parts of its distributional range. In this study, the presence of Arsenophonus-type bacteria was determined by PCR and DNA sequencing for 338 D. andersoni and 448 D. variabilis adults from western Canada. Fifty-one (15%) of the D. andersoni were found to be infected with Arsenophonus, whereas only a single D. variabilis was infected. The prevalence of Arsenophonus in D. andersoni varied among localities (0–27%). The 16S rDNA sequences of Arsenophonus in Canadian D. andersoni and D. variabilis were identical to one another, but the results of a phylogenetic analysis showed that they were genetically distinct from,
and may represent a different species to, the Arsenophonus in D. variabilis and Amblyomma americanum in eastern USA. 相似文献
11.
Microbially unexplored medicinal plants can have a genetically diverse microbial population with multi-functional plant growth promoting traits. In this aspect, 75 endophytic bacterial isolates with plant growth promoting traits were isolated from Withania coagulans Dunal and Olea ferruginea Royal. Many of these bacteria were able to solubilize phosphate, produce indole-3-acetic acid, ammonia as well as hydrogen cyanide, synthesize extracellular enzymes and show antagonistic activities against plant pathogenic fungi under in vitro conditions. These isolates were also characterized by morphological and biochemical analysis. Furthermore, four representative isolates with pronounced plant growth promoting activities were identified as Enterobacter cloacae, Enterobacter dissolvens, Enterobacter hormaechei and Cronobacter sakazakii by 16S rDNA sequencing analysis. This work for the first time, reported the isolation of endophytic bacteria, the novel association form selected plants, Withania coagulans and Olea ferruginea. The explored endophytes might have great potential in the field of biocontrol and plant growth promoting for sustainable agricultural practices. 相似文献
12.
Kakinuma Y Hayashi K Tazumi A Hirayama J Moore JE Millar BC Kuribayashi T Matsuda M 《Folia microbiologica》2011,56(2):159-165
13.
Endosymbiotic bacteria that potentially influence reproduction and other fitness-related traits of their hosts are widespread
in insects and mites and their appeal to researchers’ interest is still increasing. We screened 20 strains of 12 agriculturally
relevant herbivorous and predatory mite species for infection with Wolbachia, Cardinium and Spiroplasma by the use of PCR. The majority of specimens originated from Austria and were field collected or mass-reared. Eight out of
20 strains (40%) tested, representing seven of 12 mite species (58%), carried at least one of the three bacteria. We found
Wolbachia in the herbivorous spider mites Tetranychus urticae and Bryobia rubrioculus, with the former also carrying Spiroplasma and the latter also carrying Cardinium. Cardinium was furthermore found in two populations of the predatory mite Euseius finlandicus and the spider mite Eotetranychus uncatus. Spiroplasma was detected in the predatory mite Neoseiulus californicus. All bacteria positive PCR products were sequenced, submitted to GenBank and analyzed in BLAST queries. We found high similarities
to complete identity with bacteria found in the same and different mite species but also with bacteria found in insect species
like ladybirds, butterflies and minute pirate bugs, Orius. We discuss the significance of potential (multiple) infections with the investigated bacteria for biological control. 相似文献
14.
Kang MS Oh JS Lee SW Lim HS Choi NK Kim SM 《Journal of microbiology (Seoul, Korea)》2012,50(1):137-142
While it is generally accepted that Propionibacterium acnes is involved in the development of acne, other bacteria including Staphylococcus epidermidis have also been isolated from the acne lesion. The interaction between Lactobacillus reuteri, a probiotic bacterium, and acnegenic bacteria is unclear. This study examined the effects of L. reuteri on the proliferation of P. acnes and S. epidermidis. Human-derived L. reuteri strains (KCTC 3594 and KCTC 3678) and rat-derived L. reuteri KCTC 3679 were used. All strains exhibited significant inhibitory effects on the growth of P. acnes and S. epidermidis. The proliferation of P. acnes was decreased by 2-log scales after incubation with L. reuteri for 24 h. In addition, the proliferation of S. epidermidis was decreased by 3-log scales after incubation with L. reuteri for 24 h, whereas the growth of L. reuteri was unaffected by P. acnes or S. epidermidis. Among the L. reuteri strains examined, L. reuteri KCTC 3679 had the strongest inhibitory effect on the growth of P. acnes and S. epidermidis, followed by L. reuteri KCTC 3594 and L. reuteri KCTC 3678. Interestingly, reuterin, an antimicrobial factor, was produced only by L. reuteri KCTC 3594. The most pronounced the antibacterial activities of L. reuteri were attributed to the production of organic acids. Overall, these results suggest that L. reuteri may be a useful probiotic agent to control the growth of bacteria involved in acne inflammation and prevent acne. 相似文献
15.
Mobilization of two P element subfamilies (canonical and O-type) from Drosophila sturtevanti and D. saltans was evaluated for copy number and transposition activity using the transposon display (TD) technique. Pairwise distances
between strains regarding the insertion polymorphism profile were estimated. Amplification of the P element based on copy number estimates was highly variable among the strains (D. sturtevanti, canonical 20.11, O-type 9.00; D. saltans, canonical 16.4, O-type 12.60 insertions, on average). The larger values obtained by TD compared to our previous data by
Southern blotting support the higher sensitivity of TD over Southern analysis for estimating transposable element copy numbers.
The higher numbers of the canonical P element and the greater divergence in its distribution within the genome of D. sturtevanti (24.8%) compared to the O-type (16.7%), as well as the greater divergence in the distribution of the canonical P element, between the D. sturtevanti (24.8%) and the D. saltans (18.3%) strains, suggest that the canonical element occupies more sites within the D. sturtevanti genome, most probably due to recent transposition activity. These data corroborate the hypothesis that the O-type is the
oldest subfamily of P elements in the saltans group and suggest that the canonical P element is or has been transpositionally active until more recently in D. sturtevanti. 相似文献
16.
Pascal Montoro Sébastien Lagier Christelle Baptiste Benjamin Marteaux Valérie Pujade-Renaud Julie Leclercq Laurence Alemanno 《Plant Cell, Tissue and Organ Culture》2008,94(1):55-63
In this article we describe the identification of endophytic bacteria belonging to three groups isolated from shoot tip cultures
of banana cv. Grand Naine in a recent study (Thomas et al. 2008) based on partial 16S rRNA gene sequence homology analysis. The first group included banana stocks that displayed obvious
colony growth on MS based tissue culture medium during the first in vitro passage. The second group constituted stocks that
were tissue index-negative for cultivable bacteria initially but turned index-positive after a few to several (4–8) in vitro
passages while the third group formed one sub-stock that turned index-positive after about 18 passages. The organisms belonged
to about 20 different genera comprising of α, β, γ-proteobacteria, Gram-positive firmicutes and actinobacteria. Visibly expressing easily cultured organisms during the first
in vitro passage included Enterobacter, Klebsiella, Ochrobactrum, Pantoea, Staphylococcus and Bacillus spp. Organisms of second group that were not detected or non-culturable originally constituted Brevundimonas, Methylobacterium, Alcaligenes, Ralstonia, Pseudomonas, Corynebacterium, Microbacterium, Staphylococcus, Oceanobacillus and Bacillus spp. while the third group that turned cultivable after extended in vitro culturing included mostly non-filamentous actinobacteria
(Brachybacterium, Brevibacterium, Kocuria and Tetrasphaera spp.). The identification results suggested that the endophytes of second and third groups were not strictly obligate or
fastidious microbes but those surviving in viable but-non-culturable (VBNC) state and displaying gradual activation to cultivable
form during continuous tissue culturing. Several of the organisms isolated are known as beneficial ones in agriculture while
some organisms have possible implications in human health. The use of tissue cultures for isolating uncommon endophytes is
discussed.
Supply of live bacterial cultures or genetic material for research purpose is subject to their revival from glycerol stocks
(as some of the organisms showed poor tolerance) and the requestor obtaining written permission from the Director General,
Indian Council of Agricultural Research, New Delhi-110001. 相似文献
17.
Background
Elucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development. 相似文献18.
Young Tae Kim Kang Seon Lee Moon Jung Kim Seung Bum Kim 《Journal of microbiology (Seoul, Korea)》2009,47(1):33-39
The effects of Chinese cabbage (Brassica rapa subsp. pekinensis) carrying cry1AC derived from Bacillus thuringiensis (Bt) on leaf bacterial community were examined by analyzing the horizontal transfer of trans-gene fragments from plants to
bacteria. The effect of plant pathogenic bacteria on the gene transfer was also examined using Pseudomonas syringae pathovar. maculicola. The frequency of hygromycin-resistant bacteria did not alter in Bt leaves, though slight increase was observed in Pseudomonas-infected Bt leaves with no statistical significance. The analysis of bacterial community profiles using the denaturing gradient
gel electrophoresis (DGGE) fingerprinting indicated that there were slight differences between Bt and control Chinese cabbage,
and also that infected tissues were dominated by P. syringae pv. maculicola. However, the cultured bacterial pools were not found to contain any transgene fragments. Thus, no direct evidence of immediate
gene transfer from plant to bacteria or acquisition of hygromycin resistance could be observed. Still, long-term monitoring
on the possibility of gene transfer is necessary to correctly assess the environmental effects of the Bt crop on bacteria. 相似文献
19.
Ingo Schmidt 《Current microbiology》2009,59(2):130-138
The ammonia oxidizers Nitrosomonas europaea and Nitrosomonas eutropha are able to grow chemoorganotrophically under anoxic conditions with pyruvate, lactate, acetate, serine, succinate, α-ketoglutarate,
or fructose as substrate and nitrite as terminal electron acceptor. The growth yield of both bacteria is about 3.5 mg protein
(mmol pyruvate)−1 and the maximum growth rates of N. europaea and N. eutropha are 0.094 d−1 and 0.175 d−1, respectively. In the presence of pyruvate and CO2 about 80% of the incorporated carbon derives from pyruvate and about 20% from CO2. Pyruvate is used as energy and only carbon source in the absence of CO2 (chemoorganoheterotrophic growth). CO2 stimulates the chemoorganotrophic growth of both ammonia oxidizers and the expression of ribulose bisphosphate carboxylase/oxygenase
is down-regulated at increasing CO2 concentration. Ammonium, although required as nitrogen source, is inhibitory for the chemoorganotrophic metabolism of N. europaea and N. eutropha. In the presence of ammonium pyruvate consumption and the expression of the genes aceE, ppc, gltA, odhA, and ppsA (energy conservation) as well as nirK, norB, and nsc (denitrification) are reduced. 相似文献