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1.
Field experiments were conducted in 2004 and 2005 to determine the effects of seed treatment with Rhizobium leguminosarum bv. viceae on damping‐off, seedling height, root nodule mass, root biomass, shoot biomass and seed yield of pea and lentil in a field naturally infested with Pythium spp. Compared with the untreated controls, treatment of pea seeds with R. leguminosarum bv. viceae strains R12, R20 or R21 significantly (P < 0.05) reduced incidence of damping‐off, promoted seedling growth and increased root nodule mass, root biomass and shoot biomass. Seed treatments with R12 or R21 also resulted in a significant (P < 0.05) increase in seed yield of pea. The strain R21 was most effective among the four strains of R. leguminosarum bv. viceae tested in peas. Although, the level of disease control by strain R21 was similar to seed treatment with the fungicide ThiramTM, R21 was more effective in enhancing root nodule production and promoting plant growth. For lentil, treatment of seeds with R. leguminosarum bv. viceae strains R12 or R21 significantly (P < 0.05) reduced incidence of damping‐off compared with the untreated control. All of the four strains of R. leguminosarum bv. viceae tested increased lentil seedling height, root nodule mass and shoot biomass, and all except R20 increased root biomass. Seed yield was higher for the treatments of R12 and R21. The strain R12 was most effective among the four strains of R. leguminosarum bv. viceae tested in lentil. Although, strain R12 was as effective as ThiramTM for control of damping‐off of lentil, it was more effective than ThiramTM for the production of root nodules and promotion of plant growth. The study concludes that seed treatment with R. leguminosarum bv. viceae is effective in control of Pythium damping‐off of pea and lentil and that the efficacy of control is strain specific, strain R21 for control of the disease on pea and strain R12 for control of the disease on lentil.  相似文献   

2.
This study examines the amount of biomass loss occurring in Miscanthus × giganteus crop at harvest. The study assesses loss incurred as a direct result of the harvest systems employed to collect the material along with examining how the time of harvest effects the amount of loss occurring over the spring harvest window. Pre harvest losses of 4.8–5.1% were measured prior to harvest. There was no significant difference between pre harvest loss and post harvest loss when a self‐propelled forage harvester fitted with a maize harvesting header was used to harvest the crop. The use of a conditioner mower and baler significantly increased crop losses to 9.4–14.1%. This demonstrates that correct selection of the harvest system can significantly increase biomass recovery. Additional losses were measured at headlands when the mower/baler system was used, but headland losses will not occur when self‐propelled forage harvesters are utilized. Losses were significantly greater in the area beside the swath after the baler pass when compared to prior to baling. This study has shown that correct selection of harvest systems can significantly increase biomass recovery, with no significant difference in pre harvest loss or harvest loss occurring as a result of cutting the M. × giganteus crop at different dates during the harvest window (March 1st, March 25th, April 21st).  相似文献   

3.
A microalgal strain was established from Cepsa's refinery wastewater treatment plant in Huelva (southwest of Spain). Genetic analysis of the chloroplastic rbcL gene encoding for the large subunit of the ribulose bisphosphate carboxylase enzyme (Rubisco) showed the strain had high homology with other known rbcL sequences of the genus Chlorella. The strain grows well autotrophically in minimum mineral medium, with a growth rate of 0.28 ± 0.012 day?1 and a biomass productivity of 138.9 ± 6.7 mg L?1 day?1. N‐starvation and/or over illumination with 650 µmol photons m?2 s?1 of PAR light on the cultures induced a significant increase in the intracellular content of lipids in this microalga. Total lipids were extracted from the strain biomass with 2:1 chloroform‐methanol, and they accounted for approximately 50% of the dry biomass. Polyunsaturated fatty acids (PUFAs) represented 60.4% of the total fatty acids found in the strain, thus making this biomass attractive as a high added‐value product source. The strain was able to grow efficiently in the refinery treated wastewater from which it was isolated, providing an attractive advantage for further development of more sustainable algal biomass production processes at reduced costs close to a petrol refinery area.  相似文献   

4.
Effect of hydrogen uptake positive (Hup+) strain ofRhizobium sp. (pigeon pea) and VAM fungus (Glomus fasciculatum) was studied on the symbiotic parameters of pigeon pea (Cajanus cajan) cv. AL-15 at various levels of phosphorus. The Hup+ Rhizobium strain showed more nodulation, plant biomass and plant nitrogen content than its Hup counterpart. VAM infection in pigeon pea roots helped in translocating phosphorus from the soil and improved nitrogen fixation. Similarly, addition of phosphorus was found to play a positive role in enhancing all these parameters. Dual inoculation of Hup+ Rhizobium strain and VAM significantly increased nodulation, nitrogenase activity, plant nitrogen and phosphorus content and plant biomass compared to single inoculation of either organism and dual inoculation with Hup and VAM fungus.  相似文献   

5.
The use of Trametes versicolor as a biological pretreatment for canola straw was explored in the context of biofuel production. Specifically, the effects on the straw of a wild-type strain (52 J) and a cellobiose dehydrogenase (CDH)-deficient strain (m4D) were investigated. The xylose and glucose contents of the straw treated with 52 J were significantly reduced, while only the xylose content was reduced with m4D treatment. Lignin extractability was greatly improved with fungal treatments compared to untreated straw. Saccharification of the residue of the m4D-treated straw led to a significant increase in proportional glucose yield, which was partially attributed to the lack of cellulose catabolism by m4D. Overall, the results of this study indicate that CDH facilitates cellulose access by T. versicolor. Furthermore, treatment of lignocellulosic material with m4D offers improvements in lignin extractability and saccharification efficacy compared to untreated biomass without loss of substrate due to fungal catabolism.  相似文献   

6.
Summary Non-living biomass from the thermotolerant, ethanol-producing yeast strain Kluyveromyces marxianus IMB3 is capable of uranium biosorption. The biomass has an observed biosorption capacity of 115mg uranium/g dry weight of biomass with a calculated value of 127mg uranium/g dry weight. Following exposure of the biomass to electric fields of 2,500 V/cm for 20msec. the maximum biosorption capacity (observed or calculated) for uranium did not differ significantly for the untreated biomass. However, at lower residual concentrations of uranium (<10mg/L) the capacity of the treated biomass for uranium was significantly increased above values obtained with untreated material.  相似文献   

7.
SUMMARY.
  • 1 Research was performed in laboratory streams to evaluate periphytic biomass accrual, export, and community composition over a range of limiting nutrient (phosphorus) concentrations with variable velocity, and suspended sediment addition, in comparison to constant velocity and no suspended sediment. In fixed-velocity treatments, velocity increase to 60 cm s?1 significantly enhanced biomass accrual, but further increase resulted in substantial biomass reduction. Average biomass loss rates did not change significantly over a velocity range of 10–80 cm s?1. Diatoms were favoured at relatively high velocities and low phosphorus concentrations, whereas the blue-green Phormidium tended to dominate at higher SRP concentrations and the green Mougeotia seemed to prefer lower velocities.
  • 2 Sudden increases in velocity raised instantaneous loss rates by an order of magnitude or more, but these high rates persisted only briefly. As a result, marked biomass reductions were not apparent a day after the velocity change. Dominance change from filamentous green or blue-green to diatoms immediately after the increase was reversed within 2 days. Loss rate increases due to solids addition were much smaller than those accompanying velocity increase, but simultaneous velocity elevation and solids addition produced instantaneous loss rates approximately double those with velocity increase alone.
  • 3 The experiments demonstrated that an elevation in velocity, above that to which algae were accustomed, led to increased loss rates and temporarily reduced biomass. However, recolonization and growth after biomass reduction were apparently rapid. Substantial export of periphyton following solids addition required erosion of the protective boundary layer accompanied by a velocity increase. These results arc applicable to understanding the response of lotic periphytic algae to elevated, turbid storm discharges and similar runoff or high-flow events.
  • 4 Areal uptake rates of P by algae growing in the laboratory streams increased with soluble reactive phosphorus (SRP) concentration, up to approximately 15 μg I?1 in overlying water. They also increased above 35 cm s ?1. Overall, uptake rate seemed to vary inversely with biomass. The ralio of areal uptake rate/biomass was significantly less where mean biomass was 411±6 mg chl a m?2 compared to 223±17 mg chl a m?2.
  • 5 The results suggested that although nutrient uptake is primarily a surface phenomenon, diffusion to interior cells can also determine the responses of attached communities. Both diffusion and uptake rate were stimulated by increasing nutrient concentration and velocity up to certain levels, but became limited by biofilm thickness and scouring.
  相似文献   

8.
We conducted a microcosm experiment with monocultures and all possible combinations of four aquatic hyphomycete species, Articulospora tetracladia, Flagellospora curta, Geniculospora grandis and Heliscus submersus, to examine the potential effects of species richness on three functional aspects: leaf litter decomposition (leaf mass loss), fungal production (ergosterol buildup) and reproductive effort (released spores). Both species richness and identity significantly affected fungal biomass and conidial production (number and biomass of released spores), whereas only species identity had a significant effect on leaf mass loss. In mixed cultures, all measures of fungal functions were greater than expected from the weighted performances of participating species in monoculture. Mixed cultures outperformed the most active monoculture for biomass accumulation but not for leaf mass loss and conidial production. The three examined aspects of aquatic hyphomycete activity tended to increase with species richness, and a complementary effect was unequivocally demonstrated for fungal biomass. Our results also suggest that specific traits of certain species may have a greater influence on ecosystem functioning than species number.  相似文献   

9.
In October 1988, Hurricane Joan struck reefs in the San Blas Island, Panama, where hurricanes had never been recorded. Effects on large erect sponges were dramatic. For several years before the hurricane, the three most common sponges had been studied, providing pre-storm data on population structure and dynamics. Nearly half the individuals and biomass of three species were lost in the storm. The species were not affected in the same way, even though they are all of erect branching growth forms. Iotrochota birotulata lost significantly more individuals chan Amphimedon rubens (57.6% vs 42.9%), which lost significantly more individuals than Aplysina fulva (31.6%). Patterns of biomass loss were very different, with both Iotrochota and Aplysina suffering losses of about 50%, but Amphimedon losing only 4.9%. Patterns of loss appear to be related to differences between species in the relative proportions of spicules (siliceous) and spongin (protein) in skeletal fibers and by differences in the speed and success rate of fragment reattachment. The incidence of toppling due to base failure varied among the six most common large erect sponge species, with significantly less toppling of the two species with skeletons composed solely of spongin. Clones of Iotrochota birotulata characterized by harrow branches suffered disproportionately greater losses than clones with more robust branches. The abundance of very small sponges, possibly developed from sexually produced larvae, was an order of magnitude higher after the storm than before.  相似文献   

10.
Batch experiments were designed to characterize a multiple metal resistant bacterium Burkholderia sp. D54 isolated from metal contaminated soils in the Dabaoshan Mine in South China, and a follow-up experiment was conducted to investigate the effects of inoculating the isolate on plant growth and metal uptake by Sedum alfredii Hance grown on soils collected from a heavily contaminated paddy field in Daxing County, Guangxi Zhuang Automounous Region, Southwest China. Our experiments showed that strain D54 produced indole acetic acid (IAA), siderophores, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and solubilizing inorganic phosphate and solubilized insoluble metal bearing minerals. Bacterial inoculation significantly enhanced S. alfredii biomass production, and increased both shoot and root Cd concentration, but induced little variation in root/shoot Pb concentration and shoot Zn concentration. Despite this, the total shoot and root uptake of Cd, Pb and Zn in S. alfredii inoculated with D54 increased greatly compared to the non-inoculated controls. It was concluded that inoculation with strain D54 could help S. alfredii grow better on metal contaminated soils, produce more biomass, and remove more metals from soil, which implies improved efficiency of phytoextraction from metal contaminated soil. The knowledge gained from the present experiments constitutes an important advancement in understanding of the interaction between plant growth-promoting bacteria and hyperaccumulators with regard to plant ability to grow and remove the multiple heavy metals from soils.  相似文献   

11.
Pseudomonas aeruginosa was isolated from infected burn patients and characterized by standard biochemical tests. The in vitro copper uptake was compared between this isolated pathogenic strain and two non-pathogenic control strains of Gram positive bacteria Bacillus thuringiensis strain Israelis as well as Gram negative bacteria Enterobacter aerogenes. Maximum copper uptake of 470 ppm/g biomass was obtained by P. aeruginosa strain, while the control strains B. thuringiensis and Enterobacter aerogenes had copper uptake of 350 and 383 ppm/g biomass, respectively. However, the lowest copper uptake (60 ppm/g biomass) was observed with another control the saprophytic strain Pseudomonas (Shewanella) putrefaciens. A further investigation regarding the effect of copper toxicity on bacterial growth, gave an MIC score of 600 ppm for P. aeruginosa strain compared to 460 and 300 ppm for the two Gram positive and Gram negative control strains, respectively. In tandem with these in vitro findings, blood analysis on burn patients infected with P. aeruginosa has indicated a selective decrease of copper (hypocupremia) and ceruloplasmin plasma levels. The iron metabolism was also affected by this copper deprivation leading to a similar decrease in plasma levels of PCV, iron, total iron binding capacity, and transferrin. All these hematological changes were significantly different (P < 0.05) from the matched group of non-infected burn patients. The observed hypocupremia in infected burn patients was attributed to demanding scavenger ability by P. aeruginosa strain for the copper of plasma.  相似文献   

12.
Acidified glycerol pretreatment is very effective to deconstruct lignocellulosics for producing glucose. Co‐utilization of pretreated biomass and residual glycerol to bioproducts could reduce the costs associated with biomass wash and solvent recovery. In this study, a novel strain Rhodosporidium toruloides RP 15, isolated from sugarcane bagasse, was selected and tested for coconversion of pretreated biomass and residual glycerol to microbial oils. In the screening trails, Rh. toruloides RP 15 demonstrated the highest oil production capacity on glucose, xylose, and glycerol among the 10 strains. At the optimal C:N molar ratio of 140:1, this strain accumulated 56.7, 38.3, and 54.7% microbial oils based on dry cell biomass with 30 g/L glucose, xylose, and glycerol, respectively. Furthermore, sugarcane bagasse medium containing 32.6 g/L glucose from glycerol‐pretreated bagasse and 23.4 g/L glycerol from pretreatment hydrolysate were used to produce microbial oils by Rh. toruloides RP 15. Under the preliminary conditions without pH control, this strain produced 7.7 g/L oil with an oil content of 59.8%, which was comparable or better than those achieved with a synthetic medium. In addition, this strain also produced 3.5 mg/L carotenoid as a by‐product. It is expected that microbial oil production can be significantly improved through process optimization.  相似文献   

13.
Herbivory of invertebrates on submerged macrophytes from Danish freshwaters   总被引:5,自引:0,他引:5  
1. Invertebrate herbivory on submerged freshwater macrophytes, measured as per cent leaf area lost, was determined for sixteen species and forty-two populations of macrophytes during peak summer biomass in Danish streams and lakes. 2. All seventeen Potamogeton populations and seventeen of the remaining twenty-five non-Potamogeton populations were grazed. Species of Potamogeton were significantly more heavily grazed (mean 4.2%) than non-Potamogeton species (mean 0.8%). Herbivory losses were not significantly different between stream (mean 2.4%) and lake populations (mean 1.9%). Wide ranges in herbivory loss were observed between species from the same locality and within species from different localities. The location of main damage to either old or young leaves was not species specific but varied among localities. Additional data for four macrophyte populations showed that herbivory loss had a strong seasonal variation (e.g. 1.0–26.3% for Potamogeton perfoliatus), with maximum losses during May-June. 3. Although the mean defoliation percentages were low during the period of maximum macrophyte biomass, they were not systematically lower than encountered for terrestrial plants.  相似文献   

14.
Summary The propene isolated strain Xanthobacter Py2 was able to grow on 1-pentene. The biomass yield for growth under 1-pentene limiting conditions was 0.48 (Ceq/Ceq). Upon storage at both +4°C and -20°C no loss of enzymatic epoxide degrading activity in resting cell suspensions was observed after a month. However, activity decay was pronounced during the stationary phase of growth as well as under reaction conditions.  相似文献   

15.
Fungal inoculation and elevated CO2 may mediate plant growth and uptake of heavy metals, but little evidence from Diffusive Gradients in Thin-films (DGT) measurement has been obtained to characterize the process. Lolium mutiforum and Phytolacca americana were grown at ambient and elevated CO2 on naturally Cd and Pb contaminated soils inoculated with and without Trichoderma asperellum strain C3 or Penicillium chrysogenum strain D4, to investigate plant growth, metal uptake, and metal bioavailability responses. Fungal inoculation increased plant biomass and shoot/root Cd and Pb concentrations. Elevated CO2 significantly increased plants biomass, but decreased Cd and Pb concentrations in shoot/root to various extents, leading to a metal dilution phenomenon. Total Cd and Pb uptake by plants, and DGT-measured Cd and Pb concentrations in rhizosphere soils, were higher in all fungal inoculation and elevated CO2 treatments than control treatments, with the combined treatments having more influence than either treatment alone. Metal dilution phenomenon occurred because the increase in DGT-measured bioavailable metal pools in plant rhizosphere due to elevated CO2 was unable to match the increase in requirement for plant uptake of metals due to plant biomass increase.  相似文献   

16.
The population heterogeneity of recombinant and plasmid-freeBacillus subtilis strains introduced into aquatic microcosms was studied. After introduction, the population of the plasmid-free strainB. subtilis 2335 in microcosms has long been represented by both vegetative cells and spores, whereas, already ten days after introduction, the population of the recombinant strainB. subtilis 2335/105 (KmrInf+) was represented only by spores. The number of plasmid copies in the spore isolates of the recombinant strain was the same as before introduction, but the plasmid abundance in the vegetative isolates of this strain decreased. The isolates ofB. subtilis 2335/105 obtained from microcosms and the variants of this strain obtained by ten successive subcultures on M9 and 0. I× M9 media with and without kanamycin (Km) differed in the number of plasmid copies, Km resistance, and maximum biomass yield during batch cultivation. Irrespective of the presence of Km, more than 50% of the variants subcultured on M9 medium showed reduced plasmid abundance. At the same time, about 70% of the variants subcultured on 0.1 × M9 medium with Km and 90% of the variants subcultured on the same medium without Km retained the initial number of plasmid copies. The variants subcultured on media with Km retained the initial biomass level. In more than 70% of the variants isolated from media without Km, the biomass yield increased.  相似文献   

17.
Phenol degradation efficiency of cold-tolerant Arthrobacter sp. AG31 and mesophilic Pseudomonas putida DSM6414 was compared. The cold-tolerant strain was cultivated at 10°C, while the mesophile was grown at 25°C. Both strains degraded 200 mg and 400 mg phenol/l within 48–72 h of cultivation, but the cold-tolerant strain produced more biomass than the mesophile. Both strains oxidized catechol by the ortho type of ring fission. Catechol 1,2 dioxygenase (C1,2D) activity was found intra- and extracellularly in the absence and in the presence of phenol. In the presence of 200 mg phenol/l, C1,2D activity of the mesophile was about 1.5- to 2-fold higher than that of the cold-tolerant strain. However, an initial phenol concentration of 400 mg/l resulted in a comparable enzyme activity of the cold-tolerant and the mesophilic strain. The two strains differed significantly in their toxicity pattern towards 12 aromatic (mostly phenolic) compounds at different growth temperatures, which was determined via growth inhibition in the presence of nutrients and toxicants. For the cold-tolerant strain, toxicity was significantly lower at 10°C than at 25°C. The mesophile showed a significantly lower susceptibility to high hydrocarbon concentrations when grown at 25°C compared to 10°C.Communicated by K. Horikoshi  相似文献   

18.
Artificial amplification of gluconeogenic phosphoenolpyruvate carboxykinase (PCK) under glycolytic conditions enables Escherichia coli to maintain a greater intracellular ATP concentration during its growth phase. To demonstrate the biotechnological benefit of E. coli harboring a high intracellular ATP concentration, we compared the recombinant protein synthesis of a soluble protein (enhanced green fluorescence protein, GFP) with that of a secretory protein (alkaline protease, AP), under control of the T7 promoter in E. coli BL21(DE3) overexpressing PCK. According to the batch fermentations, the strain overexpressing PCK produced more GFP and AP with a lower increase in biomass than the control strain. In a chemostat culture (D = 0.7 h−1), the GFP production in the PCK overexpressing strain was 99.0 ± 4.31 mg/g cell, with a biomass of 0.22 g/L, while that of the control strain was 53.5 ± 3.07 mg/g cell, with a biomass of 0.35 g/L. These results indicate that the PCK overexpressing E. coli strain harboring high intracellular levels of ATP can be useful as a protein-synthesizing host. The potential uses of the strain and associated rationale are discussed.  相似文献   

19.
Drought is one of the major abiotic stresses affecting yield of dryland crops. Rhizobacterial populations of stressed soils are adapted and tolerant to stress and can be screened for isolation of efficient stress adaptive/tolerant, plant growth promoting rhizobacterial (PGPR) strains that can be used as inoculants for crops grown in stressed ecosystems. The effect of inoculation of five drought tolerant plant growth promoting Pseudomonas spp. strains namely P. entomophila strain BV-P13, P. stutzeri strain GRFHAP-P14, P. putida strain GAP-P45, P. syringae strain GRFHYTP52, and P. monteilli strain WAPP53 on growth, osmoregulation and antioxidant status of maize seedlings under drought stress conditions was investigated. Drought stress induced by withholding irrigation had drastic effects on growth of maize seedlings. However seed bacterization of maize with Pseudomonas spp. strains improved plant biomass, relative water content, leaf water potential, root adhering soil/root tissue ratio, aggregate stability and mean weight diameter and decreased leaf water loss. The inoculated plants showed higher levels of proline, sugars, free amino acids under drought stress. However protein and starch content was reduced under drought stress conditions. Inoculation decreased electrolyte leakage compared to uninoculated seedlings under drought stress. As compared to uninoculated seedlings, inoculated seedlings showed significantly lower activities of antioxidant enzymes, ascorbate peroxidase (APX), catalase (CAT), glutathione peroxidase (GPX) under drought stress, indicating that inoculated seedlings felt less stress as compared to uninoculated seedlings. The strain GAP-P45 was found to be the best in terms of influencing growth and biochemical and physiological status of the seedlings under drought stress. The study reports the potential of rhizobacteria in alleviating drought stress effects in maize.  相似文献   

20.
《Fungal Ecology》2011,4(6):417-426
Chemical composition of litter has previously been reported to affect in situ decomposition. To identify its effects on a single species level, the saprotrophic basidiomycete Hypholoma fasciculare was grown on 11 types of litter with variable chemical composition (N content of 3.4–28.9 mg g−1), and the mass loss of litter and lignin, production of extracellular enzymes and fungal biomass were followed. After 12 weeks, mass loss ranged from 16 % to 34 %. During early decomposition stages, litter mass loss, fungal biomass production (estimated by ergosterol content) as well as fungal substrate use efficiency all increased with increasing initial N content of the litter. The initial litter decomposition rate was significantly positively correlated with the activities of arylsulfatase, cellobiohydrolase, endoxylanase and phosphatase. Contrary to expectations, the lignin content did not affect litter mass loss, when covariation with N content was accounted for. The ratio of lignin loss to total mass loss depended on the litter type and did not reflect the activities of ligninolytic enzymes.  相似文献   

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