共查询到20条相似文献,搜索用时 46 毫秒
1.
Dario Frascari Giacomo Bucchi Francesco Doria Antonella Rosato Nasrin Tavanaie Raffaele Salviulo Roberta Ciavarelli Davide Pinelli Serena Fraraccio Giulio Zanaroli Fabio Fava 《Biodegradation》2014,25(3):337-350
A procedure for the design of an aerobic cometabolic process for the on-site degradation of chlorinated solvents in a packed bed reactor was developed using groundwater from an aquifer contaminated by trichloroethylene (TCE) and 1,1,2,2-tetrachloroethane (TeCA). The work led to the selection of butane among five tested growth substrates, and to the development and characterization from the site’s indigenous biomass of a suspended-cell consortium capable to degrade TCE (first order constant: 96 L g protein –1 day–1 at 30 °C and 4.3 L g protein –1 day–1 at 15 °C) with a 90 % mineralization of the organic chlorine. The consortium immobilization had strong effects on the butane and TCE degradation rates. The microbial community structure was slightly changed by a temperature shift from 30 to 15 °C, but remarkably affected by biomass adhesion. Given the higher TCE normalized degradation rate (0.59 day–1 at 15 °C) and attached biomass concentration (0.13 gprotein L bioreactor –1 at 15 °C) attained, the porous ceramic carrier Biomax was selected as the best option for the packed bed reactor process. The low TeCA degradation rate exhibited by the developed consortium suggested the inclusion of a chemical pre-treatment based on the TeCA to TCE conversion via β-elimination, a very fast reaction at alkaline pH. To the best of the authors’ knowledge, this represents the first attempt to develop a procedure for the development of a packed bed reactor process for the aerobic cometabolism of chlorinated solvents. 相似文献
2.
Growth and metabolism characteristics of anaerobic ammonium-oxidizing bacteria aggregates 总被引:1,自引:0,他引:1
Ting-Ting Chen Ping Zheng Li-Dong Shen 《Applied microbiology and biotechnology》2013,97(12):5575-5583
The present study reported the growth and metabolism characteristics of anaerobic ammonium-oxidizing (anammox) bacteria aggregates in an expanded granular sludge bed (EGSB). The results showed that the anammox bacteria aggregates presented starvation, growth, and inhibition phase along with the increase of substrate supply. The substrate conversion rates for survival were 0.05 kgNH 4 + –N/(kgVSS·day), 0.07 kgNO 2 ? –N/(kgVSS·day), and 0.12 kgN/(kgVSS·day); the substrate conversion rates for maximum growth were 0.21 kgNH 4 + –N/(kgVSS·day), 0.24 kgNH 4 + –N/(kgVSS·day), and 0.45 kgNH 4 + –N/(kgVSS·day), respectively. In the growth phase, the yield of anammox bacteria aggregates was 0.14 gVSS/(gNH 4 + –N), 0.12 gVSS/(gNO 2 ? –N), and 0.70 gVSS/(gNO 3 ? –N); the yield of extracellular polymeric substances (EPS) was 0.11 gEPS/(gNH 4 + –N), 0.09 gEPS/(gNO 2 ? –N), and 0.55 gEPS/(gNO 3 ? –N), respectively. The EPS contents in anammox bacteria aggregates were high compared to that in anaerobic granular sludge. Speculated from the cell yield, the energy for anammox bacteria growth was not only from nitrite oxidation, but also from anammox reaction. 相似文献
3.
Atmospheric nitrogen inputs and losses along an urbanization gradient from Boston to Harvard Forest,MA 总被引:1,自引:0,他引:1
Urbanization alters nitrogen (N) cycling, but the spatiotemporal distribution and impact of these alterations on ecosystems are not well-quantified. We measured atmospheric inorganic N inputs and soil leaching losses along an urbanization gradient from Boston, MA to Harvard Forest in Petersham, MA. Atmospheric N inputs at urban sites (12.3 ± 1.5 kg N ha?1 year?1) were significantly greater than non-urban (5.7 ± 0.5 kg N ha?1 year?1) sites with NH4 + (median value of 77 ± 4 %) contributing thrice as much as NO3 ?. Proximity to urban core correlated positively with NH4 + (R2 = 0.57, p = 0.02) and total inorganic N inputs (R2 = 0.61, p = 0.01); on-road CO2 emissions correlated positively with NO 3 ? inputs (R2 = 0.74, p = 0.003). Inorganic N leaching rates correlated positively with atmospheric N input rates (R2 = 0.61, p = 0.01), but did not differ significantly between urban and non-urban sites (p > 0.05). Our empirical measurements of atmospheric N inputs are greater for urban areas and less for rural areas compared to modeled regional estimates of N deposition. Five of the nine sites had NO 3 ? leached that came almost entirely from nitrification, indicating that the NO3 ? in leachate came from biological processes rather than directly passing through the soil. A significant proportion (17–100 %) of NO 3 ? leached from the other four sites came directly from the atmosphere. Surprisingly, the four sites where atmospheric sources made up the largest proportion of leachate NO3 ? also had relatively low N leaching rates, suggesting that atmospheric N inputs added to terrestrial ecosystems can move to multiple sinks and losses simultaneously, rather than being lost via leaching only after abiotic and biotic sinks have become saturated. This study improves our understanding of atmospheric N deposition and leaching in urban ecosystems, and highlights the need to incorporate urbanization effects in N deposition models. 相似文献
4.
Effects of nitrate concentration on the denitrification potential of a calcic cambisol and its fractions of N2, N2O and NO 总被引:1,自引:0,他引:1
Rui Wang Qi Feng Tingting Liao Xunhua Zheng Klaus Butterbach-Bahl Wei Zhang Chunyi Jin 《Plant and Soil》2013,363(1-2):175-189
Background and aims
The direct measurement of denitrification dynamics and its product fractions is important for parameterizing process-oriented model(s) for nitrogen cycling in various soils. The aims of this study are to a) directly measure the denitrification potential and the fractions of nitrogenous gases as products of the process in laboratory, b) investigate the effects of the nitrate (NO 3 ? ) concentration on emissions of denitrification gases, and c) test the hypothesis that denitrification can be a major pathway of nitrous oxide (N2O) and nitric oxide (NO) production in calcic cambisols under conditions of simultaneously sufficient supplies of carbon and nitrogen substrates and anaerobiosis as to be found to occur commonly in agricultural lands.Methods
Using the helium atmosphere (with or without oxygen) gas-flow-soil-core technique in laboratory, we directly measured the denitrification potential of a silt clay calcic cambisol and the production of nitrogen gas (N2), N2O and NO during denitrification under the conditions of seven levels of NO 3 ? concentrations (ranging from 10 to 250 mg N kg?1 dry soil) and an almost constant initial dissolved organic carbon concentration (300 mg C kg?1 dry soil).Results
Almost all the soil NO 3 ? was consumed during anaerobic incubation, with 80–88 % of the consumed NO 3 ? recovered by measuring nitrogenous gases. The results showed that the increases in initial NO 3 ? concentrations significantly enhanced the denitrification potential and the emissions of N2 and N2O as products of this process. Despite the wide range of initial NO 3 ? concentrations, the ratios of N2, N2O and NO products to denitrification potential showed much narrower ranges of 51–78 % for N2, 14–36 % for N2O and 5–22 % for NO.Conclusions
These results well support the above hypothesis and provide some parameters for simulating effects of variable soil NO 3 ? concentrations on denitrification process as needed for biogeochemical models. 相似文献5.
B. Matejek C. Huber M. Dannenmann M. Kohlpaintner R. Gasche H. Papen 《Plant and Soil》2010,337(1-2):93-110
Microbial N turnover processes were investigated in three different forest soil layers [organic (O) layer, 0–10 cm depth (M1), 10–40 cm depth (M2)] after the clear cutting of a nitrogen (N) saturated spruce stand at the Höglwald Forest (Bavaria, Germany). The aim of the study was to provide detailed insight into soil-layer specific microbial production and the consumption of inorganic N within the main rooting zone. Furthermore, we intended to clarify the relevance of each soil layer investigated in respect of the observed high spatial variation of seepage water nitrate (NO 3 ? ) concentration at a depth of 40 cm. The buried bag and the 15N pool dilution techniques were applied to determine the net and gross N turnover rates. In addition, soil pH, C:N ratio, pool sizes of soil ammonium (NH 4 + ) and NO 3 ? , as well as quantities of microbial biomass carbon (Cmic) and nitrogen (Nmic) were determined. The 40 cm thick upper mineral soil was found to be the main place of NO 3 ? production with a NO 3 ? supply or net nitrification three times higher than in the considerably thinner O layer. Nevertheless, O layer nitrification processes determined via in situ field experiments showed significant correlation with seepage water NO 3 ? . An improved correlation noted several months after the cut may result from a transport-induced time shift of NO 3 ? with downstream hydrological pathways. In contrast, the soil laboratory incubation experiments found no indication that mineral soil is relevant for the spatial heterogeneity of seepage water NO 3 ? . The results from our study imply that in situ experiments may be better suited to studies investigating N turnover in relation to NO 3 ? loss via seepage water in similar ecosystems in order to gain representative data. 相似文献
6.
Xingliang Xu Hua Ouyang Guangmin Cao Andreas Richter Wolfgang Wanek Yakov Kuzyakov 《Plant and Soil》2011,341(1-2):495-504
Niche partitioning by time, space and chemical forms has been suggested as an important mechanism to maintain species coexistence. Climate warming is assumed to increase soil nutrient availability through enhancing mineralization of soil organic matter in a variety of terrestrial ecosystems. However, few studies have yet examined how dominant plant species contribute to species coexistence when nutrient enrichment occurs in native ecosystems. We studied a single fairy ring (5 m diameter) in a Kobresia meadow in the Tibetan Plateau. This kind of rings is caused by a basidiomycete fungus Agaricus campestris, and is evidenced by dark-green vegetation boundaries. Nutrient enrichment occurs due to enhanced decomposition of soil organic matter (SOM) in the fungus growth zone of these rings. We conducted a short-term 15N labelling experiment and found that dominant plant species shifted their N uptake patterns and preferred N form (NO 3 ? , NH 4 + , and amino acid N) in response to nutrient enrichment in an N-limited alpine meadow. The legume Gueldenstaedtia diversifolia had the lowest aboveground biomass among the five plant species studied at low available N level, although it mainly utilized ammonium (the most abundant N form). The two graminoids (Elymus nutans and Stipa aliena) demonstrated similar aboveground biomass at low and high available N levels, showing a similar pattern switching from NH 4 + /NO 3 ? uptake outside the ring to glycine uptake in the annulus zone of the ring. The biomass of the forb Gentiana straminea differed significantly at low and high available N levels, but its N uptake pattern almost remained unchanged. Species therefore differed in their response to nutrient enrichment, most species showing chemical niche shifts instead of niche conservatism. This finding has important implications with regard to understanding the mechanisms responsible for species coexistence when natural nutrient enrichment is induced by climate warming in terrestrial ecosystems. 相似文献
7.
Wei Cui Heng-min Cui Xi Peng Zhicai Zuo Xiaodong Liu Bangyuan Wu 《Biological trace element research》2011,141(1-3):192-199
The purpose of this 42-day study was to investigate the effects of dietary excess vanadium on immune function by determining changes of the subsets and proliferation function of peripheral blood T cells. Four hundred twenty 1-day-old avian broilers were divided into six groups and fed on a corn–soybean basal diet as control diet or the same diet amended to contain 5, 15, 30, 45, and 60 ppm vanadium supplied as ammonium metavanadate. In comparison with those of the control group, the percentages of CD 3 + , CD 3 + CD 4 + , and CD 3 + CD 8 + were decreased in 45 and 60 ppm groups from 14 to 42 days of age, and the percentages of CD 3 + and CD 3 + CD 4 + were increased in 5 ppm group at 42 days of age. The CD 4 + /CD 8 + ratio was increased in 45 and 60 ppm groups at 28 days of age. Meanwhile, the proliferation function of peripheral blood T cell were decreased in 30, 45, and 60 ppm groups from 14 to 42 days of age. Also, the serum interleukin-2 contents were decreased in 45 and 60 ppm groups from 14 to 42 days of age and increased in 5 ppm group at 28 days of age. Histopathologically, hypocellularity appeared in the thymus in 45 and 60 ppm groups. It was concluded that dietary vanadium in excess of 30 ppm reduced the percentages of peripheral blood T-cell subsets and the proliferation function and serum interleukin-2 contents. The cellular immune function was finally impaired in broilers. 相似文献
8.
The effects of wetting and drying and inorganic nitrogen (N) addition on carbon (C) and N turnover in fresh Douglas fir litter (Speuld forest, the Netherlands) were investigated. Litter was incubated for 9 days in the laboratory, receiving different moisture and N addition treatments. Following the additions, a series of reactions were observed of which most notable were a rapid retention of added ammonium and nitrate (NO 3 - ) and a sudden increase in CO2 respiration. For the rewetted-and-moist incubations, respiration levels remained elevated, N was net immobilized and nitrous oxide (N2O) production increased throughout the experiment. About 80% of the NO 3 - produced was lost again as N2O. In the rewetted-and-dried incubations, respiration decreased during the drying phase; no clear patterns in N mineralization were detected; and N2O production remained at constant levels, but still resulted in gaseous loss for half of the NO 3 - net produced. The experiments thus revealed two important NO 3 - sinks in LF1 litter, namely rapid retention of added NO 3 - and gaseous loss as N2O. The maximum NO 3 - loss via these sinks was estimated at 2 kg-N ha-1 yr-1, which is small compared to annual NO 3 - leaching at 90 cm soil depth (31 kg-N ha-1 yr-1). 相似文献
9.
10.
L. Malardé A. Rebillard S. Le Douairon-Lahaye S. Vincent M. S. Zguira S. Lemoine-Morel A. Gratas-Delamarche C. Groussard 《Molecular and cellular biochemistry》2014,389(1-2):113-118
Superoxide (O 2 ·? ) overproduction, by decreasing the nitric oxide (·NO) bioavailability, contributes to vascular complications in type 1 diabetes. In this disease, the vascular O 2 ·? can be produced by the NADPH oxidase (NOX), nitric oxide synthase (NOS), and xanthine oxidase (XO). This study aimed to determine the contribution of each enzymatic pathway in hyperglycemia-induced O 2 ·? overproduction, and the effects of an endurance training program and insulin therapy, associated or not, on the O 2 ·? production (amount and related enzymes) in diabetic rats. Forty male Wistar rats were divided into diabetic (D), diabetic treated with insulin (D-Ins), diabetic trained (D-Tr), or diabetic insulin-treated and trained (D-Ins + Tr) groups. An additional healthy group was used as control. Insulin therapy (Glargine Lantus, Sanofi) and endurance training (treadmill run: 60 min/day, 25 m/min, 5 days/week) started 1 week after diabetes induction by streptozotocin (45 mg/kg), and lasted for 8 weeks. At the end of the protocol, the O 2 ·? production in aorta rings was evaluated by histochemical analyses (DHE staining). Each production pathway was studied by inhibiting NOX (apocynin), NOS (L-Name), or XO (allopurinol) before DHE staining. Diabetic rats exhibited hyperglycemia-induced O 2 ·? overproduction, resulting from NOX, NOS, and XO activation. Insulin therapy and endurance training, associated or not, decreased efficiently and similarly the O 2 ·? overproduction. Insulin therapy reduced the hyperglycemia and decreased the three enzymatic pathways implicated in the O 2 ·? production. Endurance training decreased directly the NOS and XO activity. While both therapeutic strategies activated different pathways, their association did not reduce the O 2 ·? overproduction more significantly. 相似文献
11.
Xiaodong Ding Changyan Tian Shirong Zhang Jie Song Fusuo Zhang Guohua Mi Gu Feng 《Plant and Soil》2010,331(1-2):57-67
The influence of NO 3 ? -N on growth and osmotic adjustment was studied in Tamarix laxa Willd., a halophyte with salt glands on its twigs. Seedlings of T. laxa Willd. were exposed to 1 mM (control) or 300 mM NaCl, with 0.05, 1 or 10 mM NO 3 ? -N for 24 days. The relative growth rate of seedlings at 300 mM NaCl was lower than that of control plants at all NO 3 ? -N levels, but the concentrations of organic N and total N in the twigs did not differ between the two NaCl treatments. Increasing NO 3 ? supply under 300 mM NaCl improved the growth of T. laxa, indicating that NO 3 ? played positive roles in improving salt resistance of the plant. The twigs of T. laxa Willd. accumulated mainly inorganic ions, especially Na+ and Cl?, to lower osmotic potential (Ψs): the contributions of Na+ and Cl? to Ψs were estimated at 31% and 27% respectively, at the highest levels of supply of both NaCl and NO 3 ? -N. The estimated contribution of NO 3 ? -N to Ψs was as high as 20% in the twigs in these conditions, indicating that NO 3 ? was also involved in osmotic adjustment in the twigs. Furthermore, increases in tissue NO 3 ? were accompanied by decreases in tissue Cl? and proline under 300 mM NaCl. The estimated contribution of proline to Ψs declined as with NO 3 ? -N supply increased from 1 to 10 mM, while the contributions of nitrate to Ψs were enhanced under 300 mM NaCl. This suggested that higher accumulation of nitrate in the vacuole alleviated the effects of salinity stress on the plant by balancing the osmotic potential. In conclusion, NO 3 ? -N played both nutritional and osmotic roles in T. laxa Willd. in saline conditions. 相似文献
12.
A 15N tracing study was carried out to investigate the potential gross nitrogen (N) dynamics in thirteen forest soils in Eastern China ranging from temperate to tropical zones (five coniferous forests, six deciduous broad-leaf forests, one temperate mixed forest, one evergreen broad-leaf forests ecosystems), and to identify the major controlling factors on N cycling in these forest ecosystems. The soil pH ranged from 4.3 to 7.9 and soil organic carbon (SOC) ranged from 6.6 g?kg?1 to 83.0 g?kg?1. The potential gross N transformation rates were quantified by 15N tracing studies where either the ammonium or nitrate pools were 15N labeled in parallel treatments. Gross mineralization rates ranged from 0.915 μg N g?1 soil day?1 to 2.718 μg N g?1 soil day?1 in the studied forest soils. The average contribution of labile organic-N (M Nlab ) to total gross mineralization (M Nrec +M Nlab ) was 86% (58% to 99%), indicating that turnover of labile organic N plays a dominant role in the studied forest ecosystems. The gross mineralization rates in coniferous forest soils were significantly lower (ranging between 0.915 and 1.228 μg N g?1 soil day?1) compared to broad-leaf forest soils (ranging from 1.621 to 2.718 μg N g?1 soil day?1) (p?<?0.01). Thus, the dominant vegetation may play an important role in regulating soil N mineralization. Nitrate production (nitrification) occurred via two pathways, oxidation of NH 4 + and organic N the forest soils. Correlations with soil pH indicated that this is a key factor controlling the oxidation of NH 4 + and organic N in theses forest ecosystems. NH 4 + oxidation decreased with a decline in pH while organic N oxidation increased. The climatic conditions (e.g. moisture status) at the various sites governed the NO 3 ? -N consumption processes (dissimilatory NO 3 ? reduction to NH 4 + (DNRA) or immobilization of NO 3 ? ). Total NO 3 ? consumption and the proportion of total NO 3 ? consumption to total NO 3 ? production decreased with an increase in the drought index of ecosystems, showing that strong interactions appear to exist between climatic condition (e.g. the drought index), N mineralization and the rate of DNRA. Interactions between vegetation, climatic conditions govern internal N cycling in these forests soils. 相似文献
13.
Sanjay K. Singh Chamroeun Heng Jay D. Braker Victor J. Chan Charles C. Lee Douglas B. Jordan Ling Yuan Kurt Wagschal 《Journal of industrial microbiology & biotechnology》2014,41(3):489-498
Directed evolution of β-xylosidase XylBH43 using a single round of gene shuffling identified three mutations, R45K, M69P, and L186Y, that affect thermal stability parameter K t 0.5 by ?1.8 ± 0.1, 1.7 ± 0.3, and 3.2 ± 0.4 °C, respectively. In addition, a cluster of four mutations near hairpin loop-D83 improved K t 0.5 by ~3 °C; none of the individual amino acid changes measurably affect K t 0.5 . Saturation mutagenesis of L186 identified the variant L186K as having the most improved K t 0.5 value, by 8.1 ± 0.3 °C. The L186Y mutation was found to be additive, resulting in K t 0.5 increasing by up to 8.8 ± 0.3 °C when several beneficial mutations were combined. While k cat of xylobiose and 4-nitrophenyl-β-d-xylopyranoside were found to be depressed from 8 to 83 % in the thermally improved mutants, K m, K ss (substrate inhibition), and K i (product inhibition) values generally increased, resulting in lessened substrate and xylose inhibition. 相似文献
14.
Tao Chen Yun Cui Caimin Bai Tao Gong Xi Peng Hengmin Cui 《Biological trace element research》2009,132(1-3):122-128
Three hundred 1-day-old Avian broilers were divided into four groups and fed on control diet (F 23 ppm) and high-fluorine diets (400 ppm, high-fluorine group I; 800 ppm, high-fluorine group II; 1,200 ppm, high-fluorine group III) for 42 days (n?=?75/group). The percentages of CD 4 + and CD 8 + T cells were decreased in three high-fluorine groups when compared with those of control group. Meanwhile, the CD 4 + /CD 8 + ratio were lower in high-fluorine group II at 28 days of age and in high-fluorine group III at 42 days of age than in control group. Also, the serum interleukin-2 (IL-2) contents were decreased in three high-fluorine groups when compared with those of control group. Histopathologically, the thymus became hypocellular in three high-fluorine groups. It was concluded that dietary fluorine excess (400~1,200 ppm) reduced the percentages of T-lymphocyte subsets and the serum IL-2 contents, and cellular immune function could be affected in chickens. 相似文献
15.
Gustavo Calderucio Duque Estrada Mário Luiz Gomes Soares Daniel Medina Corrêa Santos Viviane Fernandez Paula Maria Moura de Almeida Marciel Rocha de Medeiros Estevam Maria Rita Olyntho Machado 《Hydrobiologia》2014,734(1):171-185
As mangroves become recognized as important carbon storages, the need for reducing the uncertainty of carbon inventories becomes increasingly emphasized. Accordingly, the objective of this study was to develop allometric models to estimate the total aboveground biomass (AGB) and the biomass per compartment of Avicennia schaueriana and to compare them with other models previously published for the genus Avicennia. Fifty three A. schaueriana trees, with different diameters at breast height (DBH) and height, were felled in a mangrove from Southeastern Brazil and their dry weight determined. Simple linear regression analysis was used to develop the equations after log-transformation, using the following independent variables: DBH and DBH2 * height. All the equations were significant and presented high R a 2 (adjusted coefficient of determination). DBH provided the lowest SEE (standard error of estimation) in the regressions associated to leaves and total AGB, while DBH2 * height generated the most precise regressions for trunk, branches, and twigs. In comparison with other 11 equations previously developed for the genus Avicennia, the equation developed in the present study for total AGB showed the lowest mean deviation in relation to trees with known biomass, underscoring the importance of developing species- and site-specific equations. 相似文献
16.
Nitrous oxide emissions and nitrate leaching from a rain-fed wheat-maize rotation in the Sichuan Basin, China 总被引:3,自引:0,他引:3
Minghua Zhou Bo Zhu Klaus Butterbach-Bahl Xunhua Zheng Tao Wang Yanqiang Wang 《Plant and Soil》2013,362(1-2):149-159
Aims
A 3-year field experiment (October 2004–October 2007) was conducted to quantify N2O fluxes and determine the regulating factors from rain-fed, N fertilized wheat-maize rotation in the Sichuan Basin, China.Methods
Static chamber-GC techniques were used to measure soil N2O fluxes in three treatments (three replicates per treatment): CK (no fertilizer); N150 (300 kg N fertilizer ha?1 yr?1 or 150 kg N?ha?1 per crop); N250 (500 kg N fertilizer ha?1 yr?1 kg or 250 kg N?ha?1 per crop). Nitrate (NO 3 ? ) leaching losses were measured at nearby sites using free-drained lysimeters.Results
The annual N2O fluxes from the N fertilized treatments were in the range of 1.9 to 6.7 kg N?ha?1 yr?1 corresponding to an N2O emission factor ranging from 0.12 % to 1.06 % (mean value: 0.61 %). The relationship between monthly soil N2O fluxes and NO 3 - leaching losses can be described by a significant exponential decaying function.Conclusions
The N2O emission factor obtained in our study was somewhat lower than the current IPCC default emission factor (1 %). Nitrate leaching, through removal of topsoil NO 3 ? , is an underrated regulating factor of soil N2O fluxes from cropland, especially in the regions where high NO 3 - leaching losses occur. 相似文献17.
Vijai Singh Karwasara Vinod Kumar Dixit 《In vitro cellular & developmental biology. Plant》2012,48(2):189-199
The effects of carbon, nitrogen, phosphate, and copper on cell growth and production of the isoflavone puerarin by suspension cultures of Pueraria tuberosa (Roxb. ex. Willd.) DC were investigated. Among the various sugars evaluated (glucose, galactose, fructose, maltose, and sucrose), use of sucrose in the medium led to the maximum accumulation of puerarin. A sucrose-feeding strategy in which additional sucrose was added to the flasks 15?d into the culture cycle stimulated both cell biomass and puerarin production. The maximum production of puerarin was obtained when a concentration balance of 20:60?mM NH 4 + /NO 3 ? was used as the nitrogen source. Alteration in the concentration balance of nitrogen components (NH 4 + /NO 3 ? 60:20?mM) or the use of either NH 4 + or NO 3 ? alone decreased biomass production and puerarin accumulation compared with the control culture (NH 4 + /NO 3 ? 20:20?mM). High amounts of phosphate (2.5 and 5?mM) in the medium inhibited puerarin production whereas 0.625?mM phosphate promoted puerarin production (68.3???g/g DW on day?25). An increase in Cu2+ concentration from 0.025 to 0.05?mg/l in the P. tuberosa cell culture medium resulted in a 2.2-fold increase in puerarin production (up to 141???g/g DW on day?25) but reduced cell culture biomass. 相似文献
18.
Ye-Zhong Zhang Hua-Rong Li Jie Dai Wen-Juan Chen Jing Zhang Yi Liu 《Biological trace element research》2010,135(1-3):136-152
The binding interaction of the cobalt(II) 1,10-phenanthroline complex (Co(phen) 3 2+ , phen = 1,10-phenanthroline) with bovine serum albumin (BSA) was investigated by fluorescence spectroscopy combined with UV–Vis absorption and circular dichroism measurements under simulative physiological conditions. The experiment results showed that the fluorescence intensity of BSA was dramatically decreased owing to the formation of Co(phen) 3 2+ –BSA complex. The corresponding association constants (K a) between Co(phen) 3 2+ and BSA at four different temperatures were calculated according to the modified Stern–Volmer equation. The enthalpy change (ΔH°) and entropy change (ΔS°) were calculated to be ?2.73 kJ mol?1 and 82.27 J mol?1?K?1, respectively, which suggested that electrostatic interaction and hydrophobic force played major roles in stabilizing the Co(phen) 3 2+ –BSA complex. Site marker competitive experiments indicated that the binding of Co(phen) 3 2+ to BSA primarily took place in site I of BSA. A value of 4.11 nm for the average distance r between Co(phen) 3 2+ (acceptor) and tryptophan residues of BSA (donor) was derived from Förster’s energy transfer theory. The conformational investigation showed that the presence of Co(phen) 3 2+ resulted in the change of BSA secondary structure and induced the slight unfolding of the polypeptides of protein, which confirmed the microenvironment and conformational changes of BSA molecules. 相似文献
19.
Xu Pang Xing-Zhong Yuan Zhen-Dong Cao Shi-Jian Fu 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2013,183(1):99-108
To investigate the effects of temperature and exercise training on swimming performance in juvenile qingbo (Spinibarbus sinensis), we measured the following: (1) the resting oxygen consumption rate $ \left( {{\dot{\text{M}}\text{O}}_{{ 2 {\text{rest}}}} } \right) $ , critical swimming speed (U crit) and active oxygen consumption rate $ \left( {{\dot{\text{M}}\text{O}}_{{ 2 {\text{active}}}} } \right) $ of fish at acclimation temperatures of 10, 15, 20, 25 and 30 °C and (2) the $ \dot{M}{\text{O}}_{{ 2 {\text{rest}}}} $ , U crit and $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ of both exercise-trained (exhaustive chasing training for 14 days) and control fish at both low and high acclimation temperatures (15 and 25 °C). The relationship between U crit and temperature (T) approximately followed a bell-shaped curve as temperature increased: U crit = 8.21/{1 + [(T ? 27.2)/17.0]2} (R 2 = 0.915, P < 0.001, N = 40). The optimal temperature for maximal U crit (8.21 BL s?1) in juvenile qingbo was 27.2 °C. Both the $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ and the metabolic scope (MS, $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} - \dot{M}{\text{O}}_{{ 2 {\text{rest}}}} $ ) of qingbo increased with temperature from 10 to 25 °C (P < 0.05), but there were no significant differences between fish acclimated to 25 and 30 °C. The relationships between $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ or MS and temperature were described as $ {\dot{\text{M}}\text{O}}_{{ 2 {\text{active}}}} = 1,214.29/\left\{ {1 + \left[ {\left( {T - 28.8} \right)/10.6} \right]^{2} } \right\}\;\left( {R^{2} = 0.911,\;P < 0.001,\;N = 40} \right) $ and MS = 972.67/{1 + [(T ? 28.0)/9.34]2} (R 2 = 0.878, P < 0.001, N = 40). The optimal temperatures for $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ and MS in juvenile qingbo were 28.8 and 28.0 °C, respectively. Exercise training resulted in significant increases in both U crit and $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ at a low temperature (P < 0.05), but training exhibited no significant effect on either U crit or $ \dot{M}{\text{O}}_{{ 2 {\text{active}}}} $ at a high temperature. These results suggest that exercise training had different effects on swimming performance at different temperatures. These differences may be related to changes in aerobic metabolic capability, arterial oxygen delivery, available dissolved oxygen, imbalances in ion fluxes and stimuli to remodel tissues with changes in temperature. 相似文献
20.
Recent measurements have demonstrated unprecedented increase in atmospheric deposition of nutrients in many parts of India. To determine whether atmospheric nutrient inputs would increase phytoplankton growth and catchment dissolved organic carbon (DOC) flushing to constrain benthic algae, we analyzed NO3 ? and PO 4 ?3 in atmospheric deposits; nutrients and DOC in runoff and lake water and standing crop biomass of phytoplankton and periphyton at Jaisamand Lake of Rajasthan, India. Atmospheric deposition of NO3 ? (7.18–29.95 kg ha?1 year?1) and PO 4 ?3 (0.56–2.15 kg ha?1 year?1) showed a consistently rising trend across the year. Microbial biomass and activity in catchment increased in response to atmospheric deposition. Lake DOC and nutrients showed strong coherence with their terrestrial and atmospheric fluxes. Phytoplankton development showed significant linearity with atmospheric input of nutrients. Air-driven input appeared to have compensated the nutrient constraints to phytoplankton during drought. The N:P stoichiometry of deposition and that of lake water indicated that, although there was a seasonal switchover to N- or P-limitation, phytoplankton were mainly co-limited by N and P due probably to the synergistic effects of combined N + P enrichment in the pelagic zone of the lake. Periphyton standing crop showed inverse relationship with phytoplankton and lake DOC. The study indicated that enhanced phytoplankton development and terrestrial DOC flushing in response to atmospheric nutrient input attenuated light penetration to constrain algal periphyton. We suggests that data on these issues may be considered in developing aquatic ecosystem models to establish future links between changing air–water–land interactions and associated shifts in lake ecosystem functioning for more accurately predicting climate change drivers and designing integrated lake basin management strategies. 相似文献