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1.
Background and aims
Iron (Fe) toxicity is a wide-spread stress in lowland rice production. The aim of this study was to differentiate between responses to acute Fe stress during the vegetative stage and chronic Fe stress throughout the growing period.Methods
Six rice genotypes were tested in a semi-artificial greenhouse setup, in which acute (almost 1500 mg L?1 Fe in soil solution during the vegetative stage) and chronic (200 to 300 mg L?1 Fe throughout the season) Fe toxicity were simulated.Results
Acute Fe stress induced early development of heavy leaf bronzing, whereas moderate symptoms occurred in the chronic treatment throughout the season. Grain yields were only reduced in the chronic stress treatment (?23 %) due to reductions in spikelet fertility, grain number and grain weight. Symptom formation during the early growth stages did not reflect yield responses in all genotypes. Only one genotype showed increases in grain Fe concentrations (24 % in the acute stress and 44 % in the chronic stress) compared to the control.Conclusions
Contrasting genotypes responded differently to acute and chronic Fe toxicity, and one genotype showed consistent tolerance and the ability to translocate excess Fe into grains. These traits can be useful in the adaptive breeding of rice for Fe toxic environments.2.
Aims
Poorly drained arctic ecosystems are potential large emitters of methane (CH4) due to their high soil organic carbon content and low oxygen availability. In wetlands, aerenchymatous plants transport CH4 from the soil to the atmosphere, but concurrently transport O2 to the rhizosphere, which may lead to oxidation of CH4. The importance of the latter process is largely unknown for arctic plant species and ecosystems. Here, we aim to quantify the subsurface oxidation of CH4 in a waterlogged arctic ecosystem dominated by Carex aquatilis ssp. stans and Eriophorum angustifolium, and evaluate the overall effect of these plants on the CH4 budget.Methods
A mesocosms study was established based on the upper 20 cm of an organic soil profile with intact plants retrieved from a peatland in West Greenland (69°N). We measured dissolved concentrations and emissions of 13CO2 and 13CH4 from mesocosms during three weeks after addition of 13C-enriched CH4 below the mesocosm.Results
Most of the recovered 13C label (>98 %) escaped the ecosystem as CH4, while less than 2 % was oxidized to 13CO2.Conclusions
It is concluded that aerenchymatous plants control the overall CH4 emissions but, as a transport system for oxygen, are too inefficient to markedly reduce CH4 emissions.3.
Jia Mi Wei Liu Xuhong Zhao Lifang Kang Cong Lin Juan Yan Tao Sang 《Biotechnology for biofuels》2018,11(1):321
Background
The greenhouse gas (GHG) mitigation is one of the most important environmental benefits of using bioenergy replacing fossil fuels. Nitrous oxide (N2O) and methane (CH4) are important GHGs and have drawn extra attention for their roles in global warming. Although there have been many works of soil emissions of N2O and CH4 from bioenergy crops in the field scale, GHG emissions in large area of marginal lands are rather sparse and how soil temperature and moisture affect the emission potential remains unknown. Therefore, we sought to estimate the regional GHG emission based on N2O and CH4 releases from the energy crop fields.Results
Here we sampled the top soils from two Miscanthus fields and incubated them using a short-term laboratory microcosm approach under different conditions of typical soil temperatures and moistures. Based on the emission measurements of N2O and CH4, we developed a model to estimate annual regional GHG emission of Miscanthus production in the infertile Loess Plateau of China. The results showed that the N2O emission potential was 0.27 kg N ha?1 year?1 and clearly lower than that of croplands and grasslands. The CH4 uptake potential was 1.06 kg C ha?1 year?1 and was slightly higher than that of croplands. Integrated with our previous study on the emission of CO2, the net greenhouse effect of three major GHGs (N2O, CH4 and CO2) from Miscanthus fields was 4.08 t CO2eq ha?1 year?1 in the Loess Plateau, which was lower than that of croplands, grasslands and shrub lands.Conclusions
Our study revealed that Miscanthus production may hold a great potential for GHG mitigation in the vast infertile land in the Loess Plateau of China and could contribute to the sustainable energy utilization and have positive environmental impact on the region.4.
Aims
The mechanisms underlying magnesium (Mg) uptake by plant roots remain to be fully elucidated. In particular, there is little information about the effects of Mg deficiency on Mg uptake activity. A Mg uptake kinetic study is essential for better understanding the Mg uptake system.Methods
We performed a Mg uptake tracer experiment in rice plants using 28?Mg.Results
Mg uptake was mediated by high- and low-affinity transport systems. The K m value of the high-affinity transport system was approximately 70 μM under Mg-deficient conditions. The Mg uptake activity was promoted by Mg deficiency, which in turn fell to the basal level after 5- min of Mg resupply. The induced uptake rate was inhibited by ionophore treatment, suggesting that an energy-dependent uptake system is enhanced by Mg deficiency.Conclusions
The Mg uptake changes rapidly with Mg conditions in rice, as revealed by a 28?Mg tracer experiment. This technique is expected to be applicable for Mg uptake analyses, particularly in mutants or other lines.5.
Shimpei Oikawa Hitomi Ehara Mika Koyama Tadaki Hirose Kouki Hikosaka Charles P. Chen Hirofumi Nakamura Hidemitsu Sakai Takeshi Tokida Yasuhiro Usui Toshihiro Hasegawa 《Plant and Soil》2017,413(1-2):231-242
Background and Aims
The effects of Sb(V), alone or combined with Se, on the growth and root development of plants are unknown. The aim of this study is to investigate the interaction between selenite and different forms of Sb and the effects on their uptake in rice and on rice root morphology.Methods
A hydroponic experiment was conducted that contained fourteen treatments. The treatment levels for Se were 0.5 and 1 mg L?1, and the treatment levels for Sb(III) and Sb(V) were 5 and 15 mg L?1.Results
Sb(V) alone significantly reduced the surface area, mean diameter and volume of the roots, whereas Sb(III) alone reduced the values of most parameters of root morphology. The addition of 1 mg L?1 Se significantly enhanced the surface area, number of medium roots, and Sb concentration in the roots subjected to 15 mg L?1 Sb(V), but it decreased the number of root forks, the number and proportion of fine roots, and the shoot Sb concentration under exposure to 15 mg L?1 Sb(III). When the plants were subjected to 1 mg L?1 Se, the addition of 15 mg L?1 Sb(III) markedly reduced the shoot and root Se concentrations and the number of root tips, root forks, and fine roots and increased the mean root diameter. However, the addition of Sb(V) did not significantly affect the root and shoot Se concentrations but significantly decreased the number of root forks and fine roots and increased the proportion of medium roots.Conclusions
Se and Sb(III) showed antagonistic effects on uptake in the shoots, but not in the roots, of paddy rice. A range of Se concentrations could stimulate the uptake of Sb in both the shoots and roots of paddy rice exposed to Sb(V).6.
Xiaobo Dong Haiyun Li Yucheng Jiang Mancheng Hu Shuni Li Quanguo Zhai 《Biotechnology letters》2016,38(9):1483-1491
Objectives
To degrade enzymatically bisphenol A (BPA) that causes serious environmental concerns and is difficult to be degraded by chemical or physical methods.Results
BPA (150 mg l?1) was completely degraded by chloroperoxidase (CPO)/H2O2 within 7 min at room temperature, atmospheric pressure with the enzyme at 6 μg CPO ml?1. The degradation products were identified by HPLC–MS, which suggested involvement of multiple steps. Enzymatic treatment followed by existing bioremediation technologies (activated sludge) enhanced removal of COD from 9 to 54 %. Using an ecotoxicity evaluation with Chlorella pyrenoidosa, the degradation products had a lower toxicity than BPA.Conclusion
BPA can be degraded rapidly and efficiently under mild conditions with chloroperoxidase at 6 μg ml?1. The degradation products had a lower toxicity than BPA.7.
Robert P. Jeffery Richard J. Simpson Hans Lambers Daniel R. Kidd Megan H. Ryan 《Plant and Soil》2017,412(1-2):21-34
Aims
Trifolium subterraneum L. is the predominant annual pasture legume in southern Australia. Cultivars with improved phosphorus (P) foraging ability would improve the P-use efficiency of agricultural systems. We therefore investigated variation in root traits related to P-uptake among six cultivars.Methods
Micro-swards were grown at six levels of P in field soil with indigenous arbuscular mycorrhizal (AM) fungi for six weeks. Dry matter yield, tissue P concentration, rhizosphere carboxylates, AM fungal colonisation and root morphological traits were measured.Results
The cultivars showed similar shoot and root yield responses to P supply. Average root diameter did not change, specific root length (SRL) increased and root tissue density (RTD) decreased with increased P supply. Amounts of total rhizosphere carboxylates were low (<1.2 nmol cm?1 root). The percentage of root length colonised by AM fungi was greatest (29–43 %) at an intermediate level (8 mg kg?1 dry soil) of P supply.Conclusions
Most differences among cultivars were reasonably consistent across P supply levels, indicating greater numbers of lines could be screened reliably at a single P level. Low colonisation by AM fungi at low P supply deserves consideration when selecting soils for cultivar comparisons. Increased SRL and decreased RTD at high P supply likely result from self-shading within the micro-swards and warrant further investigation.8.
Gaoxiang Qi Lian Xiong Xiaoqing Lin Chao Huang Hailong Li Xuefang Chen Xinde Chen 《Biotechnology letters》2017,39(1):97-104
Objective
To investigate the inhibiting effect of formic acid on acetone/butanol/ethanol (ABE) fermentation and explain the mechanism of the alleviation in the inhibiting effect under CaCO3 supplementation condition.Results
From the medium containing 50 g sugars l?1 and 0.5 g formic acid l?1, only 0.75 g ABE l?1 was produced when pH was adjusted by KOH and fermentation ended prematurely before the transformation from acidogenesis to solventogenesis. In contrast, 11.4 g ABE l?1 was produced when pH was adjusted by 4 g CaCO3 l?1. The beneficial effect can be ascribed to the buffering capacity of CaCO3. Comparative analysis results showed that the undissociated formic acid concentration and acid production coupled with ATP and NADH was affected by the pH buffering capacity of CaCO3. Four millimole undissociated formic acid was the threshold at which the transformation to solventogenesis occurred.Conclusion
The inhibiting effect of formic acid on ABE fermentation can be alleviated by CaCO3 supplementation due to its buffering capacity.9.
Aim
Our objectives were to compare effects of root charge properties on Al adsorption by the roots of rice that differed in Al-tolerance, and to examine effects of different nitrogen forms on charge properties of rice roots and Al adsorption.Methods
Streaming potential and chemical methods were used to measure root zeta potential and investigate Al chemical forms adsorbed on the roots of rice obtained from solution culture experiments.Results
Rice roots of the Al-sensitive variety Yangdao-6 carried greater negative charge than the Al-tolerant variety Wuyunjing-7, which meant the roots of Yangdao-6 adsorbed more exchangeable and complexed Al. When both rice varieties were grown in NH4 +-containing nutrient solutions, there were less functional groups and lower negative surface charge on their roots, which reduced Al adsorption compared to the rice grown in NO3 ? containing nutrient solutions. The decline in nutrient solution pH due to NH4 + uptake by rice roots was responsible for the reduced numbers of functional groups and the lower negative surface charge on the roots compared to the rice grown in NO3 ? containing solutions.Conclusions
Integrated root surface charge, as expressed by zeta potential, played an important role in Al adsorption by the roots of rice with different Al-tolerance.10.
Tim R. Moore Muriel Abraham Margaret Kalácska Meaghan T. Murphy Catherine Potvin 《Plant and Soil》2018,425(1-2):133-143
Background and aims
We examined changes in soil organic matter arising from conversion of a 45-year old pasture to a 10 yr. old native tree plantation in Panamá, to evaluate the effect of monoculture and mixtures.Methods
We intensively sampled the soil 0–10 cm depth in the pasture in 2001 and in 22 plantation plots in 2011, ranging from 5 monocultures to 3- and 6-species treatments; samples were also taken from an undisturbed forest site. Soil analyses included organic carbon (SOC) and δ13C.Results
Conversion of the pasture to tree plantation resulted in an overall loss of SOC of 0.6 kg m?2 (18%) in the top 10 cm, but neither tree species nor diversity had a significant effect. End-member δ13C values suggested that the contribution of C3 plants to SOC was increased from 26% in the pasture to 55% after 10 years of plantation and SOC turnover times were calculated to be 21–36 yr.Conclusions
The magnitude of the loss in soil SOC is smaller than the increases in tree biomass (~3 kg C m?2) and litter (~0.3 kg C m?2) in the plantation, but still a significant part of the ecosystem C balance.11.
Objectives
To improve the production and activity of an alkaline zinc metalloprotease from Salinivibrio proteolyticus in response to ZnSO4 (ionic and nanoparticle forms) and low intensity direct electric current (LIDC).Results
A DC of 50 µA for 10 min increased enzyme production from 35 to 53 U ml?1 when applied to the stationary phase bacterial cells. Zn2+ improved enzyme production better than zinc nanoparticles (52 vs. 43.5 U ml?1). Zinc nanoparticles (0.5 mM) added to an enzyme reaction mixture containing casein (0.65 %) and 20 mM Tris/HCl buffer (pH 8) improved enzyme activity more than Zn2+ (42 vs. 36 U ml?1).Conclusion
LIDC exposure (50 µA, 10 min) to the stationary phase bacterial cells increases metalloprotease production in Salinivibrio. A low concentration of zinc nanoparticles (0.5 mM) increases maximum enzyme activity.12.
Asymmetric effects of litter removal and litter addition on the structure and function of soil microbial communities in a managed pine forest 总被引:1,自引:0,他引:1
Qiong Zhao Aimée T. Classen Wei-Wei Wang Xin-Ran Zhao Bing Mao De-Hui Zeng 《Plant and Soil》2017,412(1-2):81-96
Aims
The effect of different MeJA doses applied prior to or simultaneously with toxic Al on biochemical and physiological properties of Vaccinium corymbosum cultivars with contrasting Al resistance was studied.Methods
Legacy (Al-resistant) and Bluegold (Al-sensitive) plants were treated with and without toxic Al under controlled conditions: a) without Al and MeJA, b) 100 μM Al, c) 100 μM Al + 5 μM MeJA, d) 100 μM Al + 10 μM MeJA and e) 100 μM Al + 50 μM MeJA. MeJA was applied to leaves 24 h prior to or simultaneously with Al in nutrient solution. After 48 h, Al-concentration, lipid peroxidation (LP), H2O2, antioxidant activity, total phenols, total flavonoids, phenolic compounds and superoxide dismutase activity (SOD) of plant organs were analyzed.Results
Al-concentrations increased with Al-treatment in both cultivars, being Al, LP and H2O2 concentrations reduced with low simultaneous MeJA application. Higher MeJA doses induced more oxidative damage than the lowest. Legacy increased mainly non-enzymatic compounds, whereas Bluegold increased SOD activity to counteract Al3+.Conclusions
Low MeJA doses applied simultaneously with Al3+ increased Al-resistance in Legacy by increasing phenolic compounds, while Bluegold reduced oxidative damage through increment of SOD activity, suggesting a diminution of its Al-sensitivity. Higher MeJA doses could be potentially toxic. Studies are needed to determine the molecular mechanisms involved in the protective MeJA effect against Al-toxicity.13.
Objectives
To evaluate the influence of hydraulic retention time (HRT) and cheese whey (CW) substrate concentration (15 and 25 g lactose l?1) on the performance of EGSB reactors (R15 and R25, respectively) for H2 production.Results
A decrease in the HRT from 8 to 4 h favored the H2 yield and H2 production rate (HPR) in R15, with maximum values of 0.86 ± 0.11 mmol H2 g COD?1 and 0.23 ± 0.024 l H2 h?1 l?1, respectively. H2 production in R25 was also favored at a HRT of 4 h, with maximum yield and HPR values of 0.64 ± 0.023 mmol H2 g COD?1 and 0.31 ± 0.032 l H2 h?1 l?1, respectively. The main metabolites produced were butyric, acetic and lactic acids.Conclusions
The EGSB reactor was evaluated as a viable acidogenic step in the two-stage anaerobic treatment of CW for the increase of COD removal efficiency and biomethane production.14.
Baolong Wang Xin Wang Chris Wayne Xiangxiang Wang Lei Han Li Ye Qun Zhao Guixiang Jiang Meiqing Feng 《Biotechnology letters》2016,38(5):801-807
Objective
To produce a therapeutic protein (endostatin) by fusion with two fragments of the carboxyl-terminal peptide (CTP) of the human chorionic gonadotropin β-subunit in Pichia pastoris.Results
Two CTP sequences were fused to the C-terminal of human endostatin, and the fusion protein (endo-CTP) was expressed by P. pastoris. Endo-CTP inhibited proliferation of endothelial cells with an IC50 of 7 μg ml?1, and 30 % of cells were annexin V-positive after treatment with 20 μg endo-CTP ml?1 for 48 h. Migration of endothelial cells was inhibited by endo-CTP in a concentration-dependent manner. The half-life of endo-CTP in Sprague–Dawley rats was much longer than that of its commercial counterpart (Endostar).Conclusion
A long-acting endostatin can be produced using CTP technology.15.
Israel Díaz Ivonne Figueroa-González José Ángel Miguel Luis Bonilla-Morte Guillermo Quijano 《Biotechnology letters》2016,38(12):2097-2102
Objectives
To assess the effect of adding solid manure fractions on the biomethane potential (BMP) of liquid dairy cow manure and on the biokinetic parameters of the process.Results
The methanogenic potential of liquid dairy cow manure was strongly effected by adding a solid manure fraction. The 90/10 % (w/w) liquid/solid manure fraction mixture was the best substrate for CH4 production. This substrate mixture improved by 50 % the final CH4 production per g substrate and decreased the lag time by 220 % relative to the reference BMP test without the addition. Moreover, the addition of 20 % solid manure fraction adversely affected both the final CH4 production and the maximum methane production rate, while increased the lag time by 400 % compared to the reference BMP test without addition.Conclusions
Liquid dairy cow manure should be supplemented with no more than 10 % of solid manure fraction in order to improve the biomethane potential of this important agro-industrial residue.16.
Bernhard Zehetgruber Johannes Kobler Thomas Dirnböck Robert Jandl Rupert Seidl Andreas Schindlbacher 《Plant and Soil》2017,420(1-2):239-252
Aims
Slow or failed tree regeneration after forest disturbance is increasingly observed in the central European Alps, potentially amplifying the carbon (C) loss from disturbance. We aimed at quantifying C dynamics of a poorly regenerating disturbance site with a special focus on the role of non-woody ground vegetation.Methods
Soil CO2 efflux, fine root biomass, ground vegetation biomass, tree increment and litter input were assessed in (i) an undisturbed section of a ~ 110 years old Norway spruce stand, (ii) in a disturbed section which was clear-cut six years ago (no tree regeneration), and (iii) in a disturbed section which was clear-cut three years ago (no tree regeneration).Results
Total soil CO2 efflux was similar across all stand sections (8.5 ± 0.2 to 8.9 ± 0.3 t C ha?1 yr.?1). The undisturbed forest served as atmospheric C sink (2.1 t C ha?1 yr.?1), whereas both clearings were C sources to the atmosphere. The source strength three years after disturbance (?5.5 t C ha?1 yr.?1) was almost twice as high as six years after disturbance (?2.9 t C ha?1 yr.?1), with declining heterotrophic soil respiration and the high productivity of dense graminoid ground vegetation mitigating C loss.Conclusions
C loss after disturbance decreases with time and ground vegetation growth. Dense non-woody ground vegetation cover can hamper tree regeneration but simultaneously decrease the ecosystem C loss. The role of ground vegetation should be more explicitly taken into account in forest C budgets assessing disturbance effects.17.
Jaya Kumar Arjun Balakrishna Pillai Aneesh Thulasi Kavitha Kumarapillai Harikrishnan 《Biotechnology letters》2018,40(2):343-348
Objectives
To screen soil metagenomic libraries for novel enzymes with enhanced activities.Results
To screen soil metagenomic libraries for novel enzymes with enhanced activities. A novel l-asparaginase was identified from forest soil metagenome and its characteristics were studied. The purified protein had a specific activity of 696 IU mg?1 and optimum activity at pH 7 and 35 °C. Enhanced enzyme activities were observed in the presence of Mg2+, Ca2+ and K+. The Km value, 2 mM, and enzyme specificity constant 7.7 mM?1s?1 indicated that the recombinant enzyme has good substrate affinity to l-asparagine compared with commercially-available Escherichia coli asparaginase. The IC50 value of 0.78 µg ml?1 (0.47 IU ml?1) was observed with HL60 cell line and 0.39 µg ml?1(0.23 IU ml?1) with MOLT-3 and MOLT-4 cell lines, which is better than that of commercially-available drugs.Conclusion
The soil metagenome derived l-asparaginase with enhanced activities could be a potential candidate to develop as a drug in Acute Lymphoblastic Leukemia (ALL) therapy.18.
Objective
To produce tagatose from fructose with a high conversion rate and to establish a high-yield purification method of tagatose from the reaction mixture.Results
Fructose at 1 M (180 g l?1) was converted to 0.8 M (144 g l?1) tagatose by a three-step enzymatic cascade reaction, involving hexokinase, plus ATP, fructose-1,6-biphosphate aldolase, phytase, over 16 h with a productivity of 9 g l?1 h?1. No byproducts were detected. Tagatose was recrystallized from ethanol to a purity of 99.9% and a yield of 96.3%. Overall, tagatose at 99.9% purity was obtained from fructose with a yield of 77%.Conclusion
This is the first biotechnological production of tagatose from fructose and the first application of solvent recrystallization for the purification of rare sugars.19.
Objective
To investigate green synthesis of gold nanoparticles (AuNPs) by Trichosporon montevideense, and to study their reduction of nitroaromatics.Results
AuNPs had a characteristic absorption maximum at 535 nm. Scanning electron microscopy images revealed that the biosynthesized nanoparticles were attached on the cell surface. X-ray diffraction analysis indicated that the particles formed as face-centered cubic (111)-oriented crystals. The average size of AuNPs decreased from 53 to 12 nm with increasing biomass concentration. The catalytic reduction of 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, o-nitrophenylamine and m-nitrophenylamine (0.1 mM) by NaBH4 had reaction rate constants of 0.32, 0.44, 0.09, 0.24 and 0.39 min?1 with addition of 1.45 × 10?2 mM AuNPs.Conclusions
An eco-friendly approach for synthesis of AuNPs by T. montevideense is reported for the first time. The biogenic AuNPs could serve as efficient catalysts for hydrogenation of various nitroaromatics.20.
Improving N management through intercropping alleviates the inhibitory effect of mineral N on nodulation in pea 总被引:7,自引:0,他引:7