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1.
A strain of the fungus Gliocladium roseum YMF1.00133 was found to secrete nematicidal metabolites against nematodes Panagrellus redivivus, Caenothabditis elegans and Bursaphelenchus xylophilus in experiments searching for nematicidal fungi. Through bioassay-guided fractionations, a unique trioxopiperazine alkaloid, gliocladin C (compound 1), and an alkylane resorcinol, 5-n-heneicosylresorcinol (compound 2) were obtained from the methanol extract of the fungus and determined by single-crystal X-ray analysis and spectroscopic data. In vitro immersion experiments showed that the ED50 values of compounds 1 and 2 after 24 h incubation were 15 and 30 μg/mL against C. elegans, 50 and 80 μg/mL against P. redivivus, and 200 and 180 μg/mL against B. xylophilus, respectively. The X-ray diffraction data of compound 1 and the nematicidal activity of compounds 1 and 2 were reported for the first time.  相似文献   

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Rhizobacteria are central components of the plant microbiome and influence root development and function. Desciphering how rhizobacteria contribute to plant performance under adverse environments is a major research challenge. The aims of the present study were to isolate and characterize rhizobacteria from the halophilic grass Distichlis spicata and to test their possible growth promoting and salt protective properties in Arabidopsis thaliana, Cucumis sativus, and Citrullus lanatus. To determine their possible plant growth promoting properties, 38 rhizobacterial isolates were co-cultivated with Arabidopsis seedlings in vitro. Out of these, two halophilic bacteria, LBEndo1 and KBEcto4, were selected following their strong shoot and root biostimulation. 16S rRNA sequencing identified LBEndo1 as Bacillus sp. and KBEcto4 as Pseudomonas lini. Both strains improved growth under standard and saline conditions, which correlated with IAA and siderophore production, as well as phosphate solubilization. Additionally, the KBEcto4 strain expresses the ACC deaminase enzyme (acdS gene), and slightly increases auxin redistribution within Arabidopsis roots expressing an auxin-inducible gene construct. These data reveal the potential of saltgrass (Distichlis spicata) rhizobacteria to promote growth and confer salt tolerance to Arabidopsis and crop plants.  相似文献   

4.
Arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR) have potential to control soil-borne diseases including plant-parasitic nematodes. First, the effects of dual inoculation of mycorrhiza (Rhizophagus irregularis) and two stains of pseudomonads (Pseudomonas jessenii strain R62 and Pseudomonas synxantha strain R81) on tomato (Solanum lycopersicum cv. PT-3) growth were tested. Further, the physiological and biochemical changes caused by these beneficial organisms during infection by the root-knot nematode Meloidogyne incognita were studied. The experiment was conducted under glass house conditions and carried out up to one month after nematode inoculation. Plants treated with dual or individual inoculation of AMF and PGPR showed significantly enhanced plant growth and reduced nematode infection. In addition, they exhibited potent activity of phenolics (28 %) and defensive enzymes i.e. peroxidase (PO; 1.26 fold), polyphenyloxidase (PPO; 1.35 fold) and superoxide dismutase (SOD; 1.09 fold) while a significant reduction in malondialdehyde (MDA; 1.63 fold) and hydrogen peroxide (H2O2; 1.30 fold) content was recorded when compared to the nematode-infected plants. These findings indicate the feasibility of AMF and PGPR individually or in combinations as potential biocontrol agents for the management of root-knot nematodes.  相似文献   

5.
In eastern North America, the exotic invasive woodwasp, Sirex noctilio, attacks pines (Pinus spp.) and often shares larval habitat with the native woodwasp, Sirex nigricornis. The parasitic nematode, Deladenus siricidicola, has been used widely in the southern hemisphere as a biological control agent because it sterilizes female S. noctilio. This nematode was introduced accidentally to North America along with S. noctilio. Historical reports indicate nematode-woodwasp fidelity: the parasitic nematode, D. siricidicola, exclusively infects S. noctilio, and the native nematode, Deladenus proximus, exclusively infects S. nigricornis. From two sites in southern Ontario, separated by 225 km, we collected woodwasps from three Pinus sylvestris, and identified the nematode species present in the abdomens of infected wasps. Both wasp species co-occurred in all three trees. D. siricidicola was present in the haemocoel, but not inside the eggs, of infected S. noctilio and S. nigricornis. This evidence suggests horizontal transmission of D. siricidicola likely occurred from S. noctilio to S. nigricornis.  相似文献   

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Sixty-four native bacterial colonies were isolated from mycorrhizal roots of Helianthemum almeriense colonized by Terfezia claveryi, mycorrhizosphere soil, and peridium of T. claveryi to evaluate their effect on mycorrhizal plant production. Based on the phylogenetic analysis of the 16S rDNA partial sequence, 45 different strains from 17 genera were gathered. The largest genera were Pseudomonas (40.8 % of the isolated strains), Bacillus (12.2 % of isolated strains), and Varivorax (8.2 % of isolated strains). All the bacteria were characterized phenotypically and by their plant growth-promoting rhizobacteria (PGPR) traits (auxin and siderophore production, phosphate solubilization, and ACC deaminase activity). Only bacterial combinations with several PGPR traits or Pseudomonas sp. strain 5, which presents three different PGPR traits, had a positive effect on plant survival and growth. Particularly relevant were the bacterial treatments involving auxin release, which significantly increased the root-shoot ratio and mycorrhizal colonization. Moreover, Pseudomonas mandelii strain 29 was able to considerably increase mycorrhizal colonization but not plant growth, and could be considered as mycorrhiza-helper bacteria. Therefore, the mycorrhizal roots, mycorrhizosphere soil, and peridium of desert truffles are environments enriched in bacteria which may be used to increase the survival and mycorrhization in the desert truffle plant production system at a semi-industrial scale.  相似文献   

8.
Surveys of forests and stockpiled timber of pine, spruce, larch, and silver fir in 14 administrative subjects of the Russian Federation revealed widespread occurrence of the coniferous wood parasitic nematode Bursaphelenchus mucronatus. Twenty species of bacteria belonging to 13 genera have been detected in 25 B. mucronatus isolates, and their identity has been determined by direct sequencing of the 16S RNA gene. The most frequently occurring were bacteria from the genera Pseudomonas, Stenotrophomonas, Pantoea, Bacillus, Burkholderia, and Serratia. Prevalence of Pseudomonas brenneri and P. fluorescence, which were also found in the nematode dauer larva (LIV) isolated from the fir sawyer beetle Monochamus urussovi, have also been assessed. Two nematode B. xylophilus isolates from Portugal and one isolate from the United States have been examined, and 10 symbiotic bacteria species have been isolated, including Agrobacterium tumefacience, P. fluorescens, P. brenneri, Rahnella aquatilis, Stenotrophomonas maltophilia, S. rhizophila, and Yersinia mollaretii.  相似文献   

9.
Lucilia Robineau-Desvoidy (Diptera: Calliphoridae) is a blow fly genus of forensic, medical, veterinary, and agricultural importance. This genus is also famous because of its beneficial uses in maggot debridement therapy (MDT). Although the genus is of considerable economic importance, our knowledge about microbes associated with these flies and how these bacteria are horizontally and trans-generationally transmitted is limited. In this study, we characterized bacteria associated with different life stages of Lucilia sericata (Meigen) and Lucilia cuprina (Wiedemann) and in the salivary gland of L. sericata by using 16S rDNA 454 pyrosequencing. Bacteria associated with the salivary gland of L. sericata were also characterized using light and transmission electron microscopy (TEM). Results from this study suggest that the majority of bacteria associated with these flies belong to phyla Proteobacteria, Firmicutes, and Bacteroidetes, and most bacteria are maintained intragenerationally, with a considerable degree of turnover from generation to generation. In both species, second-generation eggs exhibited the highest bacterial phylum diversity (20 % genetic distance) than other life stages. The Lucilia sister species shared the majority of their classified genera. Of the shared bacterial genera, Providencia, Ignatzschineria, Lactobacillus, Lactococcus, Vagococcus, Morganella, and Myroides were present at relatively high abundances. Lactobacillus, Proteus, Diaphorobacter, and Morganella were the dominant bacterial genera associated with a survey of the salivary gland of L. sericata. TEM analysis showed a sparse distribution of both Gram-positive and Gram-negative bacteria in the salivary gland of L. sericata. There was more evidence for horizontal transmission of bacteria than there was for trans-generational inheritance. Several pathogenic genera were either amplified or reduced by the larval feeding on decomposing liver as a resource. Overall, this study provides information on bacterial communities associated with different life stages of Lucilia and their horizontal and trans-generational transmission, which may help in the development of better vector-borne disease management and MDT methods.  相似文献   

10.
Tricholoma matsutake is an ectomycorrhizal fungus usually associated with Pinus densiflora in South Korea. Fruiting bodies (mushrooms) of T. matsutake are economically important due to their attractive aroma; yet, T. matsutake is uncultivatable and its habitat is rapidly being eradicated due to global climate change. Root-associated bacteria can influence the growth of ectomycorrhizal fungi that co-exist in the host rhizosphere and distinctive bacterial communities are associated with T. matsutake. In this study, we investigated how these bacterial communities affect T. matsutake growth by isolating bacteria from the roots of P. densiflora colonized by ectomycorrhizae of T. matsutake and co-culturing rootassociated bacteria with T. matsutake isolates. Thirteen species of bacteria (27 isolates) were found in pine roots, all belonging to the orders Bacillales or Burkholderiales. Two species in the genus Paenibacillus promoted the growth of T. matsutake in glucose poor conditions, likely using soluble metabolites. In contrast, other bacteria suppressed the growth of T. matsutake using both soluble and volatile metabolites. Antifungal activity was more frequent in glucose poor conditions. In general, pine rhizospheres harbored many bacteria that had a negative impact on T. matsutake growth and the few Paenibacillus species that promoted T. matsutake growth. Paenibacillus species, therefore, may represent a promising resource toward successful cultivation of T. matsutake.  相似文献   

11.
Understanding the relative importance of various reproductive barriers to the early stages of speciation is an essential question in evolutionary biology. The closely related killifishes Fundulus heteroclitus and F. grandis occasionally hybridize in a small region in coastal Northeastern Florida showing that while barriers to reproduction exist, they are incomplete. The objective of this study was to elucidate barriers to reproduction between F. heteroclitus and F. grandis in the lab, as well as to quantify their strengths and relative contributions to reproductive isolation. Pre-zygotic (mating and fertilization) and post-zygotic (hatching) barriers were investigated by performing a variety of choice and no-choice laboratory mating experiments. Under no-choice conditions, barriers to mating had the greatest influence on hybrid production in F. grandis, whereas hatching barriers contributed to the majority of reproductive isolation in F. heteroclitus. Under choice conditions, however, pre-zygotic barriers had the greatest influence on hybrid production in both species. The total reproductive isolation that was observed in females of each species was stronger in F. heteroclitus than in F. grandis, and was nearly complete in F. heteroclitus females under choice conditions and was of moderate strength in F. grandis females. These results reveal an asymmetry in the potential gene flow between these two species, with F. grandis being more likely to hybridize than F. heteroclitus in the absence of environmental influences. No-choice backcrosses were also conducted and showed that at least some F1 hybrids are fertile. The observation that pre-zygotic barriers tend to be stronger than post-zygotic barriers in the early stages of speciation is consistent with similar studies in other organisms.  相似文献   

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Introduction

The human gut microbes and their metabolites are involved in multiple host metabolic pathways. Dysbiosis in the gut microbiota and altered metabolite profiles were reported in diseased state. In a region like Assam, where 12.4% of the populations are tribal population, evaluating the influence of ethnicity on gut microbiota and metabolites has become important to further differentiate it from the diseased state.

Objective

To study the influence of ethnicity on fecal metabolite profile and their association with the gut microbiota composition.

Methods

In this study, we determined the untargeted fecal metabolites from five ethnic groups of Assam (Tai-Aiton, Bodo, Karbi, Tea-tribe and Tai-Phake) using GC–MS and compared them among the tribes for common and unique metabolites. Metabolites of microbial origin were related with the available metagenomic data on gut bacterial profiles of the same ethnic groups and functional analysis were carried out based on HMDB.

Results

The core fecal metabolite profile of the Tea-tribe contained aniline, benzoate and acetaldehyde. PLS-DA based on the metabolites suggested that the individuals grouped based on their ethnicity. PCA plot of the data on bacterial abundance at the level of genus indicated clustering of individuals based on ethnicity. Positive correlations were observed between propionic acid and the genus Clostridium (R?=?0.43 and p?=?0.03), butyric acid and the genus Lactobacillus (R?=?0.45 and p?=?0.024), acetic acid and the genus Bacteroides (R?=?0.63 and p?=?0.001) and methane and the genus Escherichia (R?=?0.58 and p?=?0.002).

Conclusion

Results of this study indicated that ethnicity influences both gut bacterial profile and their metabolites.
  相似文献   

14.
Lanzhou lily (Liliumdavidii var. unicolor) is the best edible lily as well as a traditional medicinal plant in China. The microbes associated with plant roots play crucial roles in plant growth and health. However, little is known about the differences of rhizosphere microbes between healthy and wilted Lanzhou lily (Lilium davidii var. unicolor) plants. The objective of this study was to compare the rhizosphere microbial community and functional diversity of healthy and wilted plants, and to identify potential biocontrol agents with significant effect. Paired end Illumina Mi-Seq sequencing of 16S rRNA and ITS gene amplicons was employed to study the bacterial and fungal communities in the rhizosphere soil of Lanzhou lily plants. BIOLOG technology was adopted to investigate the microbial functional diversity. Our results indicated that there were major differences in the rhizosphere microbial composition and functional diversity of wilted samples compared with healthy samples. Healthy Lanzhou lily plants exhibited lower rhizosphere-associated bacterial diversity than diseased plants, whereas fungi exhibited the opposite trend. The dominant phyla in both the healthy and wilted samples were Proteobacteria and Ascomycota, i.e., 34.45 and 64.01 %, respectively. The microbial functional diversity was suppressed in wilted soil samples. Besides Fusarium, the higher relative abundances of Rhizoctonia, Verticillium, Penicillium, and Ilyonectria (Neonectria) in the wilted samples suggest they may pathogenetic root rot fungi. The high relative abundances of Bacillus in Firmicutes in healthy samples may have significant roles as biological control agents against soilborne pathogens. This is the first study to find evidence of major differences between the microbial communities in the rhizospheric soil of healthy and wilted Lanzhou lily, which may be linked to the health status of plants.  相似文献   

15.
Qishan vinegar is a typical Chinese fermented cereal product that is prepared using traditional solid-state fermentation (SSF) techniques. The final qualities of the vinegar produced are closely related to the multiple bacteria present during SSF. In the present study, the dynamics of microbial communities and their abundance in Daqu and vinegar Pei were investigated by the combination of high throughput sequencing and quantitative PCR. Results showed that the Enterobacteriales members accounted for 94.7%, 94.6%, and 92.2% of total bacterial sequences in Daqu Q3, Q5, and Q10, respectively. Conversely, Lactobacillales and Rhodospirillales dominated during the acetic acid fermentation (AAF) stage, corresponding to the quantitative PCR results. Lactobacillus, Acetobacter, Weissella, Leuconostoc and Bacillus were the dominant and characteristic bacterial genera of Qishan vinegar during AAF process. Redundancy analysis suggested that Lactobacillales and Rhodospirillales had a positive correlation with humidity and acidity, respectively. These results confirmed that the bacterial community structure could be affected by physiochemical factors, which determined the unique bacterial composition at different fermentation stages and showed batch-to-batch consistency and stability. Therefore, the conformity of bacterial community succession with physiochemical parameters guaranteed the final quality of Qishan vinegar products. This study provided a scientific perspective for the uniformity and stability of Qishan vinegar, and might aid in controlling the manufacturing process.  相似文献   

16.
The aim of this work was to evaluate the effects of co-inoculation with phosphate-solubilizing and nitrogen-fixing rhizobacteria on growth promotion, yield, and nutrient uptake by wheat. Out of twenty-five bacteria isolated from the rhizosphere soils of cereal, vegetable, and agro-forestry plants in eastern Uttar Pradesh, three superior most plant growth-promoting (PGP) isolates were characterized as Serratia marcescens, Microbacterium arborescens, and Enterobacter sp. based on their biochemical and 16S rDNA gene sequencing data and selected them for evaluating their PGP effects on growth and yield of wheat. Among them, Enterobacter sp. and M. arborescens fixed significantly higher amounts (9.32?±?0.57 and 8.89?±?0.58 mg Ng?1 carbon oxidized, respectively) of atmospheric nitrogen and produced higher amounts (27.06?±?1.70 and 26.82?±?1.63 TP 100 µg mL?1, respectively) of IAA in vitro compared to S. marcescens (8.32?±?0.39 mg Ng?1 carbon oxidized and 21.29?±?0.99 TP 100 µg mL?1). Although both M. arborescens and S. marcescens solubilized remarkable amounts of phosphate from tricalcium phosphate likely through production of organic acids, however, Enterobacter sp. was inactive. The effects of these three rhizobacteria were evaluated on wheat in alluvial soils of the Indo-Gangetic Plain by inoculation of plants with bacterial isolates either alone or in combinations in both pot and field conditions for two successive years. Rhizobacterial inoculation either alone or in consortium of varying combinations significantly (P?≤?0.05) increased growth and yield of wheat compared to mock inoculated controls. A consortium of two or three rhizobacterial isolates also significantly increased plant height, straw yield, grain yield, and test weight of wheat in both pot and field trials compared to single application of any of these isolates. Among the rhizobacterial treatment, co-inoculation of three rhizobacteria (Enterobacter, M. arborescens and S. marcescens) performed best in promotion of growth, yield, and nutrient (N, P, Cu, Zn, Mn, and Fe) uptake by wheat. Taken together, our results suggest that co-inoculation of Enterobacter with S. marcescens and M. arborescens could be used for preparation of an effective formulation of PGP consortium for eco-friendly and sustainable production of wheat.  相似文献   

17.
Overproduction of livestock manures with unpleasant odors causes significant environmental problems. The microbial fermentation bed (MFB) system is considered an effective approach to recycling utilization of agricultural byproducts and pig manure (PM). To gain a better understanding of bacterial communities present during the degradation of PM in MFB, the PM bacterial community was evaluated at different fermentation stages using 16S rRNA high throughput sequencing technology. The heatmap plot clustered five samples into short-term fermentation stage of 0–10 days and long-term fermentation stage of 15–20 days. The most abundant OTUs at the phylum level were Firmicutes, Actinobacteria and Proteobacteria in the long-term fermentation stage of PM, whereas Firmicutes, Bacteroidetes, and Proteobacteria predominated in the short-term fermentation stage of PM. At the genus level, organic degradation strains, such as Corynebacterium, Bacillus, Virgibacillus, Pseudomonas, Actinobacteria, Lactobacillus, Pediococcus were the predominate genera at the long-term fermentation stage, but were found only rarely in the short-term fermentation stage. C/N ratios increased and the concentration of the unpleasant odor substance 3-hydroxy-5-methylisoxazole (3-MI) decreased with prolonged period of fermentation. Redundancy analysis (RDA) demonstrated that the relative abundance of Firmicutes, Actinobacteria, Acidobacteria and Proteobacteria had a close relationship with degradation of 3-MI and increasing C/N ratio. These results provide valuable additional information about bacterial community composition during PM biodegradation in animal husbandry.  相似文献   

18.
Deladenus (=?Beddingia) siricidicola (Tylenchida: Neotylenchidae) is the most effective biocontrol agent used against the invasive wood wasp, Sirex noctilio (Fabricius) (Hymenoptera: Siricidae). The nematodes feed and reproduce on the wood-inhabiting fungus, Amylostereum areolatum (Chaillet ex Fr.) Boidin (Russulales: Amylostereaceae) and parasitise larvae of S. noctilio. In the nematode biocontrol program, the nematodes are inoculated into herbicide-weakened ‘trap trees’. Recent declines in nematode parasitism of S. noctilio in Australia have coincided with an increased incidence of an exotic bark beetle, Ips grandicollis (Eichhoff) (Coleoptera: Curculionidae), attacking trap trees and vectoring a wood-inhabiting fungus, Ophiostoma ips (Rumbold) Nannfelt (Ophiostomatales: Ophiostomataceae), which may inhibit migration of the nematode within the tree to the detriment of S. noctilio biocontrol. Several in vitro and in vivo experiments were conducted to investigate the effect of fungal interactions on the ability of D. siricidicola to locate and reproduce on A. areolatum. Deladenus siricidicola showed preference to A. areolatum in the presence and absence of O. ips, but the presence of O. ips negatively affected the choice response and the number of eggs laid by the nematodes. Deladenus siricidicola was unable to survive and reproduce on O. ips. Results give a clearer understanding of the choice response of D. siricidicola in I. grandicollis infested trees, explaining the disruptive impact of bark beetles on biocontrol of S. noctilio, an effect that could extend from Australia to other important pine growing countries.  相似文献   

19.
Both Bacteria and Archaea might be involved in various biogeochemical processes in lacustrine sediment ecosystems. However, the factors governing the intra-lake distribution of sediment bacterial and archaeal communities in various freshwater lakes remain unclear. The present study investigated the sediment bacterial and archaeal communities in 13 freshwater lakes on the Yunnan Plateau. Quantitative PCR assay showed a large variation in bacterial and archaeal abundances. Illumina MiSeq sequencing illustrated high bacterial and archaeal diversities. Bacterial abundance was regulated by sediment total organic carbon and total nitrogen, and water depth, while nitrate nitrogen was an important determinant of bacterial diversity. Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Chlorobi, Chloroflexi, Cyanobacteria, Firmicutes, Gemmatimonadetes, Nitrospirae, Planctomycetes, and Verrucomicrobia were the major components of sediment bacterial communities. Proteobacteria was the largest phylum, but its major classes and their proportions varied greatly among different lakes, affected by sediment nitrate nitrogen. In addition, both Euryarchaeota and Crenarchaeota were important members in sediment archaeal communities, while unclassified Archaea usually showed the dominance.  相似文献   

20.
In the present investigation, metabolites of Streptomyces sp. MTN14 and Trichoderma harzianum ThU significantly enhanced biomass yield (3.58 and 3.48 fold respectively) in comparison to the control plants. The secondary metabolites treatments also showed significant augmentation (0.75–2.25 fold) in withanolide A, a plant secondary metabolite. Lignin deposition, total phenolic and flavonoid content in W. somnifera were maximally induced in treatment having T. harzianum metabolites. Also, Trichoderma and Streptomyces metabolites were found much better in invoking in planta contents and antioxidants compared with their live culture treatments. Therefore, identification of new molecular effectors from metabolites of efficient microbes may be used as biopesticide and biofertilizer for commercial production of W. somnifera globally.  相似文献   

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