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1.
The secondary metabolites produced by Streptomyces sp. KA1-3, cultured on starch casein broth, was extracted by ethyl acetate and concentrated. Purification of the compound by thin layer chromatography lead to isolation of N-phenylpropanamide from one polar fraction. The structure of the herbicidal compound was elucidated on the basis of UV, FT-IR, mass and H1 NMR spectroscopy. The herbicidal activity of the isolate was tested against the weeds Cassia occidentalis L. and rhizome Cyperus rotundus L. by moist chamber technique and rolled towel paper assay method. Herbicidal activity of the bioactive compound N-phenylpropanamide was further evaluated under in vitro condition. The herbicidal compound showed 80% of seed germination inhibition in C. occidentalis L. and rhizome C. rotundus L. weed. The actinobacterium can be used as a source for bioherbicidal agent.  相似文献   

2.
A cultivation-based approach was employed to compare the culturable actinobacterial diversity associated with five marine sponge species (Craniella australiensis, Halichondria rugosa, Reniochalina sp., Sponge sp., and Stelletta tenuis). The phylogenetic affiliation of the actinobacterial isolates was assessed by 16S rDNA-RFLP analysis. A total of 181 actinobacterial strains were isolated using five different culture media (denoted as M1–M5). The type of medium exhibited significant effects on the number of actinobacteria recovered, with the highest number of isolates on M3 (63 isolates) and the lowest on M1 (12 isolates). The genera isolated were also different, with the recovery of three genera on M2 and M3, and only a single genus on M1. The number of actinobacteria isolated from the five sponge species was significantly different, with a count of 83, 36, 30, 17, and 15 isolates from S. tenuis, H. rugosa, Sponge sp., Reniochalina sp., and C. australiensis, respectively. M3 was the best isolation medium for recovery of actinobacteria from S. tenuis, H. rugosa, and Sponge sp., while no specific medium preference was observed for the recovery of actinobacteria from Reniochalina sp., and C. australiensis. The RFLP fingerprinting of 16S rDNA genes digested with HhaI revealed six different patterns, in which 16 representative 16S rDNAs were fully sequenced. Phylogenetic analysis indicated that 12 strains belong to the group Streptomyces, three strains belong to Pseudonocardia, and one strain belongs to Nocardia. Two strains C14 (from C. australiensis) and N13 (from Sponge sp.) have only 96.26% and 96.27% similarity to earlier published sequences, and are therefore potential candidates for new species. The highest diversity of three actinobacteria genera was obtained from Sponge sp., though the number of isolates was low. Two genera of actinobacteria, Streptomyces, and Pseudonocardia, were isolated from both S. tenuis and C. australiensis. Only the genus of Streptomyces was isolated from H. rugosa and Reniochalina sp. Sponge species have been demonstrated here to vary as sources of culturable actinobacterial diversity, and the methods for sampling such diversity presented may be useful for improved sampling of such diversity.  相似文献   

3.
The aqueous, ethyl acetate, methanolic and Total Oligomer Flavonoids (TOF) enriched extracts, obtained from the aerial parts of Cyperus rotundus, were investigated for their contents in phenolic compounds. Antioxidative activity using the NBT/riboflavin assay system, antimicrobial activity against Gram positive and Gram negative bacterial reference strains as well as antigenotoxic activity tested with the SOS chromotest assay were also studied. Significant antibacterial activity against reference strains; Staphylococcus aureus, Enterococcus faecalis, Salmonella enteritidis and Salmonella typhimurium, was detected in the presence of ethyl acetate and TOF enriched extracts. In addition to their antimicrobial activity, the same extracts showed a significant ability to inhibit nitroblue tetrazolium reduction by the superoxide radical in a non enzymatic O2.− generating system, and were also able to reduce significantly the genotoxicity induced by nifuroxazide and Aflatoxin B1. The antioxidant, antimicrobial and antigenotoxic activities exhibited by C. rotundus depend on the chemical composition of the tested extracts.  相似文献   

4.
Antimicrobial activities of rhizome extracts of Cyperus rotundus were investigated on selected plant pathogenic bacteria and fungi. Ethyl acetate and hexane extracts showed antibacterial activity against three isolates of Clavibacter michiganensis subsp. michiganensis at concentrations of 900 and 1000 μg/ml. However, Gram-negative bacterial pathogens of tomato; Pseudomonas syringae pv. tomato and Ralstonia solanacearum were not inhibited from the extracts. Ethyl acetate extracts at 100 μg/ml inhibited mycelial growth and spore germination of the two strawberry isolates of Botrytis cinerea; however, no significant inhibition was found in tomato fungal pathogen, Fusarium oxysporum f. sp. radicis lycopersici. Minimum inhibitory concentrations were determined as 0.0625 and 0.125 mg/ml against C. michiganensis subsp. michiganensis for ethyl acetate and hexane extracts of rhizomes, respectively. This study shows the potentials of extracts of C. rotundus rhizomes as antimicrobial agents that are effective against the tested plant pathogenic bacteria and fungi.  相似文献   

5.
Endophytic actinobacterial diversity in the native herbaceous plant species of Korea was analyzed using a culture-based approach. Sixty one actinobacterial strains were isolated, and assigned to 15 genera based on 16S rRNA gene analysis. The members of the genus Streptomyces comprised 45.9% of the total isolates, followed by Micromonospora (18.8%), Rhodococcus (6.6%), Microbispora (4.9%), and Micrococcus (4.9%). Other minor constituents included members of Microbacterium, Streptacidiphilus, Arthrobacter, Dietzia, Kitasatospora, Herbiconiux, Mycobacterium, Nocardia, Rathayibacter, and Tsukamurella. Among the isolates, 65.6% exhibited at least one hydrolytic enzyme activity out of four, and 45.9% exhibited antagonistic activity against at least one fungal pathogen out of five, thus demonstrating that endophytic actinobacteria can be an important source of bioactive compounds. Notably, most strains of Streptomyces proved active for both enzymatic and antagonistic activities.  相似文献   

6.
Abstract

Momilactones A (MA) and B (MB) are phytoalexins derived from rice plant (Oryza sativa) and were considered to be a part of the mechanism of rice self-defense system. The present study was to evaluate the comparative efficacies in vitro of antibacterial, fungicidal, antioxidant, and herbicidal activities of MA and MB. In general, MB shows higher antifungal, antibacterial, and herbicidal action than MA, although its antioxidant property was less than MA. In herbicidal trial, the IC50 values of MB against germination, shoot and root elongation of barnyardgrass and monochoria were 40.9, 45.5, and 27.5, and 27.1, 17.3, and 0.9 µg, respectively. For MA, these values were 40.3, 35.6, and 55.1, and 43.9, 24.3, and 0.5 µg, respectively. For antifungal activity, momilactone B (IC50: 1.2, 123.9, and 53.4 µg) exerted significantly greater inhibition than MA (IC50: 78.1, 198.1, and 95.3 µg) against Botrytis cinerea, Fusarium solani, Colletrotrichum gloeosporioides, respectively, except for Fusarium oxysporum that both MA and MB showed no marked difference. In addition, MB exhibited significantly stronger antibacterial activity than MA against Pseudomonus ovalis, Bacillus cereus, and Bacillus pumilus, whereas the inhibitory activity of the two compounds was similar against Escherichia coli. Both MA and MB exerted rather weak antioxidant activity (EC50 was 783.9 and 790.7 µg, respectively), of which MA showed a slightly stronger antioxidant activity than MB. This study is the first to examine antifungal, antibacterial, and antioxidant activities of two phytoalexins, as well as their comparative efficacies against growth of the noxious weeds barnyardgrass and monochoria.  相似文献   

7.
Ethanol extracts of Tithonia diversifolia, Cyperus rotundus and Hyptis suaveloensis have earlier been reported to have insecticidal activity against storage bruchid (Callosbrochus maculatus) reared on cowpea (Vigna unguiculata). Here, antioxidant capacities of the ethanol extracts of these plants were evaluated by determining their effects on DPPH radical scavenging, lipid peroxidation and their total phenolic contents. These extracts were further investigated for their influence on the activity of uncharacterized but purified C. maculatus glutathione S-transferases. The antioxidant properties, as a factor of total phenols and reducing power, are 0.026, 0.043; 0.21, 0.040; 0.15, 0.034 mg/ml for T. diversifolia, C. rotundus and H. suaveloensis, respectively. Using 1-chloro-2,4–dintrobenzene (CDNB) as substrate, the GST activity was inhibited in a concentration depedent manner with 50% inhibition concentration (IC50) of 87.8, 95.4 and 115.8 μg/ml for T. diversifolia, C. rotundus and H. suaveloensis, respectively. When compared with standard GSTs inhibitors, the order of inhibition was cibracon blue > triphenyltinchloride > hematin > T. diversifolia > tributyltin acetate > C. rotundus > H. suaveloensis > ethacrynic acid. These extracts bind competitively to both the active site and the hydrophobic binding site of the enzyme as presented by the Dixon and Scatchard plots. Displacement of the fluorescent probe, l-anilino-8-naphthalenesulfonate, tryptophan quenching and spectral changes induced by the plant extracts binding demonstrated a common high affinity site for which the plant secondary metabolites bind. The combinatorial competitive inhibitory approach of these plant polyphenols might contribute to the insecticidal activity against C. maculatus.  相似文献   

8.
Eleven actinobacterial strains were isolated from different plants, lentil (Lens esculentus), chickpea (Cicer arietinum L.), pea (Pisum sativum), faba bean (Vicia faba) and wheat (Triticum vulgare) from Paskerville, South Australia. Isolates were characterized and identified morphologically as well as using 16S ribosomal RNA gene sequencing. Of the actinobacteria tested, 72% produced siderophores, 33% were positive for cyanogens production, and 11% showed phosphate solubility. All isolates had antimicrobial activity against Phytophthora medicaginis, Pythium irregulare and Botrytis cinerea. In a greenhouse experiment, actinobacteria with the highest biocontrol capabilities were tested for their ability to control Phytophthora root rot on chickpea. Both Streptomyces sp. BSA25 and WRA1 successfully suppressed Phytophthora root rot when coinoculated with either Mesorhizobium ciceri WSM1666 or Kaiuroo 3. Streptomyces sp. BSA25 with either rhizobial strain enhanced vegetative growth of root (7–11 fold) and shoot dry weights (2–3 fold) compared to infected control, whereas Streptomyces sp. WRA1 increased root and shoot dry weights by 8- and 4-fold, respectively when inoculated with M. ciceri WSM1666. We suggest that careful selection of actinobacteria should be considered when coinoculated with beneficial microorganisms as plant symbionts.  相似文献   

9.
Twenty one esters of trans β-(2,4-dichlorophenoxy)acrylic acid were prepared and their inhibitory activity against shoot elongation in the rice plant and barnyard-grass was measured. The relationship between herbicidal activity and chemical structure was analysed using the Hansch approach. The selectivity (activity against barnyard-grass/activity against the rice plant) was mainly due to the lipophilic property of the esters between the two plant species.  相似文献   

10.
The aim of this study was to degrade total petroleum hydrocarbon (TPH) in a petroleum sludge contaminated site (initial TPH concentration of 65,000–75,000 mg.kg–1) with two native sedge species namely Cyperus rotundus (Linn.) and Cyperus brevifolius (Rottb.) Hassk. Fertilized and unfertilized treatments were maintained separately to record the influence of fertilizer in TPH degradation. The average biomass production (twenty plants from each treatment) of C. rotundus was 345.5 g and that of C. brevifolius was 250.6 g in fertilized soil during 360 days. Decrease in soil TPH concentration was higher in fertilized soil (75% for C. rotundus and 64% for C. brevifolius) than in unfertilized soil (36% for C. rotundus and 32% for C. brevifolius). In unvegetated treatments, decrease in soil TPH concentration in fertilized (12%) and unfertilized soil (8%) can be attributed to natural attenuation and microbial degradation. TPH accumulation in roots and shoots was significantly higher in fertilized soil in comparison to unfertilized soils (p < 0.05). Most probable number (MPN) in planted treatments was significantly higher than in unplanted treatments (p < 0.05).  相似文献   

11.
The diversity and community structures of actinobacteria in saline sediments collected from Yunnan and Xinjiang Provinces, China, were investigated with cultivation and 16S rRNA gene analysis. A total of 163 actinobacterial isolates were obtained, and they were affiliated with the order Actinomycetales (distributed into five suborders: Streptosporangineae, Micrococcineae, Streptomycineae, Pseudonocardineae, and Glycomycineae). A total of 748 actinobacterial 16S rRNA gene clones were examined, and they could be classified into Actinomycetales, Acidimicrobiales, and unclassified actinobacteria. The Actinomycetales sequences were distributed into nine suborders: Streptosporangineae, Glycomycineae, Micromonosporineae, Pseudonocardineae, Corynebacterineae, Frankineae, Propionibacterineae, Streptomycineae, and Micrococcineae. The unclassified actinobacteria contained three new clusters at the level of subclass or order. Our 16S rRNA gene phylogenetic data indicated that actinobacterial communities were very diverse in the investigated saline sediments (salinity 0.4–11.6%) and some actinobacterial members may be halotolerant or halophilic. The actinobacterial community structures in the saline sediments were different from those in marine and freshwater environments. Our data have implications for a better understanding of the distribution of Actinobacteria in saline environments. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

12.
Cercospora caricis is of interest as a potential mycoherbicide for control of purple nutsedge, Cyperus rotundus, which is considered to be the world's worst weed. The genetic variation of a collection of Brazilian Ce. caricis isolated from Cy. rotundus was analyzed by using RAPD, RFLP with a telomeric probe, [TTAGGG]18 and sequencing of the ITS1-5.8S-ITS2 regions of the ribosomal RNA gene. The Brazilian isolates were also compared with a Ce. caricis isolate from Florida, USA and with some other Cercospora species. A cluster of isolates from the Brazilian cerrado region was identified showing high genetic similarity. In contrast, isolates originating in other geographic regions of Brazil were less than 50% and 25% related to the former group according to similarity estimates produced from RAPD and telomeric RFLP analyses respectively. ITS sequence analysis did not support taxonomic division of the Brazilian strains, but did confirm the distant relatedness of these strains to the Ce. caricis isolate from Florida. The data indicate a need for an extensive molecular survey of Cercospora species associated with the Cyperaceae. Received: 12 July 2000 / Accepted: 5 September 2000  相似文献   

13.
Novel actinobacterial strains, PAGU 1247T, PAGU 1251 and PAGU 1252, were isolated from the skin of atopic dermatitis patients and were characterized using a polyphasic approach. Phylogenetic analyses based on 16S rRNA gene sequences showed that these isolates were located within the family Dermacoccaceae. The most closely related species of PAGU 1247T in phylogenetic terms was Branchiibius hedensis Mer 29717T, with 16S rRNA gene sequence similarity of 99.6%, although the DNA–DNA relatedness value was less than 43.9%. Some biochemical traits, such as lipase (C14) and α-galactosidase activity, could distinguish these isolates from B. hedensis. Strain PAGU 1247T contained iso-C16:0 and brC18:0 as the major fatty acids. The quinone system consisted of menaquinone MK-8(H6 and H4). The G + C content of the genomic DNA was 67.6 mol%. On the basis of its phenotypic properties and genetic distinctiveness, strains PAGU 1247T, PAGU 1251 and PAGU 1252 represents a novel species of the genus Branchiibius, for which the name Branchiibius cervicis sp. nov. is proposed. The type strain is PAGU 1247T (=NBRC 106593T = DSM 24166T).  相似文献   

14.
Syntheses of two carbonyl derivatives of hydantocidin 1, a potent, naturally occurring herbicide, and their herbicidal activity are described. Spiroimidazolidinone 2, the descarbonyl compound at C9, was prepared by employing reductive demethylsulfurization with tri-n-butyltin hydride as the key step. Another derivative, spiroimidazolinone 10, was obtained from α-azidoamide 8 and benzyl isocyanate via the aza-Wittig reaction. 2 had lost almost all herbicidal activity, whereas 10 retained herbicidal activity against such dicotyledonous weeds as ragweed and cocklebur, but lost activity against monocotyledonous weeds. These results imply the possibility that proper modification of the carbonyl group at C7 of the parent compound would afford hydantocidin analogues possessing crop selectivity.  相似文献   

15.
This study describes the diversity and antibacterial activity of culturable actinobacteria isolated from five species of gorgonian corals (Echinogorgia aurantiaca, Melitodes squamata, Muricella flexuosa, Subergorgia suberosa, and Verrucella umbraculum) collected in shallow water of the South China Sea. A total of 123 actinobacterial isolates were recovered using ten different isolation media, and assigned to 11 genera, including Streptomyces and Micromonospora as the dominant genera, followed by Nocardia, Verrucosispora, Nocardiopsis, Rhodococcus, Pseudonocardia, Agrococcus, Saccharomonospora, Saccharopolyspora and Dietzia. Comparable analysis indicated that the numbers of actinobacterial genera and isolates from the five gorgonian coral species varied significantly. It was found that 72 isolates displayed antibacterial activity against at least one indicator bacterium, and the antibacterial strains isolated from different gorgonians had almost the same proportion (~50 %). These results provide direct evidence for the hypotheses that gorgonian coral species contain large and diverse communities of actinobacteria, and suggest that many gorgonian-associated actinobacteria could produce some antibacterial agents to protect their hosts against pathogens. To our knowledge, this is the first report about the diversity of culturable actinobacteria isolated from gorgonian corals.  相似文献   

16.
The level of alkaline inorganic pyrophosphatase (EC 3.6.1.1) in different plant leaves varies to a great extent. Out of twenty two families comprising of fifty one species of plant leaves studied, a very high level of activity was found in leaves of Amarantus blitum and Amarantus gangeticus, which belong to the Amarantaceae family. A possible role of this enzyme in the C4 pathway of photosynthesis has been discussed. The purified enzyme from the leaf of Amarantus blitum was found to have optimum pH at 9.0, with magnesium being an absolute requirement. Excess substrate inhibits the enzyme activity.  相似文献   

17.
植物在消落带水淹结束后的陆生环境中能否合成和储存足够的碳水化合物,对其在消落带长期定居、存活和扩散具有重要影响。香附子是能够适应三峡库区消落带生境的少数多年生草本植物之一。该试验通过对消落带水淹结束后生长在深水(22~27m)、浅水(2~7m)和未淹区段香附子光合生理的定期观测,研究其在陆生环境下的光合生理变化及其形成机制。结果表明:(1)生长在深水区段香附子的净光合速率(P_n)显著高于浅水区段与未淹区段。(2)随着香附子在陆生环境中生活时间的延长,其P_n、气孔导度、表观水分利用效率、表观光能利用效率、表观CO_2利用效率增加。(3)与未淹区段相比,浅水淹没区段香附子的光饱和点显著升高,而光补偿点显著降低。研究发现,淹水胁迫后积极的自我调节能力和光合补偿机制是香附子能够适生于三峡库区消落带的重要原因。  相似文献   

18.
Abstract

Gibberellins (GAs) are well known for plant growth promotion. GAs production by fungi has received little attention, although substantial work has been carried out on other aspects of plant growth-promoting fungi (PGPF). We investigated GAs production and plant growth-promoting capacity of an endophytic fungus isolated from the roots of soil grown soybean plants. The endophytic fungus is reported as GAs producer and as PGPF for the first time in this study. Nine endophytic isolates were collected from the roots of soybean, and culture filtrates (CFs) obtained from their pure cultures were screened on Waito-C, a dwarf rice cultivar, for the presence of GAs. Of these, seven fungal isolates promoted shoot length as compared to control (distilled water), while one inhibited it. Three fungal isolates were selected on the basis of higher shoot elongation as compared to wild type Gibberella fujikuroi, which was used as positive control. The growth-prompting capacity of selected fungal isolates SB5-1, SB3-2, and SB3-3 was bio-assayed on soybean cv. Hwangkeumkong. Fungal isolate SB5-1 provided maximum plant height (31.6 cm), shoot length (21.1 cm), whole plant fresh biomass (2.41 g), shoot fresh biomass (1.99 g), and leaf area (24.37 cm2). The CF of isolate SB5-1 was analyzed for the presence of GAs, and it was found that all physiologically active GAs were present (GA1, 0.15 ng/ml, GA3, 1.2 ng/ml, GA4, 7.37 ng/ml, and GA7, 3.18 ng/ml) in conjunction with physiologically inactive GA5, GA9, GA15, GA19, GA20, and GA24. The fungal isolate SB5-1 was identified as a new strain of Cephalotheca sulfurea through molecular and phylogenetic approaches.  相似文献   

19.
Ninety-two thiolcarbamates with various substituents at the nitrogen and sulfur atoms, and their related compounds were synthesized, and their fungicidal activity against rice blast, Piricularia oryzae, and herbicidal activity against barnyardgrass, Echinochloa crus-galli, were determined in laboratory tests. The thiolcarbamate structure was necessary for the high fungicidal and herbicidal activities. The hydrophobicity of the substituents at the nitrogen atom was shown by the adaptive least-squares (ALS) method to be favorable to the fungicidal activity. The bulkier the substituents at the nitrogen atom, the less was the fungicidal activity. However, bulkiness of the substituents at the nitrogen and sulfur atoms was unfavorable to the herbicidal activity. The existence of a hydrogen atom at the nitrogen atom was favorable to fungicidal activity, but not to herbicidal activity. Correlation analyses were made to find compounds with both fungicidal and herbicidal activities against rice pests.  相似文献   

20.
Pomelo seeds (PS) are important by-product of pomelo fruits (Citrus grandis Osbeck). The value-added utilization of PS remains highly challenged. This study aimed to investigate the utilization potential of PS as natural antioxidant, antibacterial, herbicidal agents, and their functional components. The ethanolic extract (EE) of PS and its four fractions as PEE (petroleum ether extract), AcOEtE (ethyl acetate extract), BTE (butanol extract), and WE (water extract), were prepared and biologically evaluated. BTE exhibited the best antioxidant activity among all these extracts, in both ABTS (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) and FRAP (ferric reducing antioxidant power) assays. AcOEtE was superior to other extracts in herbicidal assay against both Festuca elata Keng (IC50 of 0.48 mg mL−1) and Amaranthus retroflexus L. (IC50 of 0.94 mg mL−1). Meanwhile, both AcOEtE and BTE demonstrated inhibitory effects against Bacillus subtilis, Escherichia coli, and Xanthomonas citri subsp. citri, with MIC ranging 2.5–5.0 mg mL−1. Furthermore, the primary chemical components involving naringin, deacetylnomilin, limonin, nomilin, and obacunone, were quantified in all these extracts. PCA (principal component analysis) suggested that naringin might highly contribute to the antioxidant activity of PS, and the herbicidal activity should be ascribed to limonoids. This study successfully identified AcOEtE and BTE as naturally occurring antioxidant, antibacterial, and herbicidal agents, showing application potential in food and cosmetics industries, and organic farming agriculture.  相似文献   

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