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1.
C. Lynne McIntyre Ky L. Mathews Allan Rattey Scott C. Chapman Janneke Drenth Mohammadghader Ghaderi Matthew Reynolds Ray Shorter 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,120(3):527-541
Grain yield and grain weight of wheat are often decreased by water-limitation in the north-eastern cropping belt of Australia.
Based on knowledge that CIMMYT lines are well-adapted in this region, a recombinant inbred line (RIL) population between two
elite CIMMYT bread wheats (Seri M82 and Babax) was evaluated under water-limited environments. Fourteen productivity traits
were evaluated in 192 progeny in up to eight trials. For three aggregations of the environments (all, high yield or low yield),
multiple quantitative trait loci (QTL) were detected, each explaining <15% of variation. Co-location of multiple trait QTL
was greatest on linkage groups 1B-a, 1D-b, 4A-a, 4D-a, 6A-a, 6B-a, 7A-a and an unassigned linkage group. Two putative QTL
(LOD > 3) from Seri (6D-b and UA-d) increased grain yield and co-located with a suggestive (2 < LOD < 3) and a putative QTL
for increased stem carbohydrate content (WSC), respectively; the latter QTL also co-located with a putative anthesis QTL for
earlier flowering. Both QTL were detected only in high yield (>4t ha−1) environments. A third increased grain yield QTL (7A-a) from Babax co-located with QTL for increased grain number. Six putative
QTL increased grain weight and co-located with QTL for harvest index, grains per spike and spike number. Three putative QTL
for increased grains per spike co-located with strong QTL for earlier flowering, increased grain weight and fewer spikes.
A group of progeny that exceeded the mean grain yield and grain weight of commercial checks had an increased frequency of
QTL for high WSC, large grain size, increased harvest index and greater height, but fewer stems, when compared to low yielding
(20% less), low grain weight progeny. These findings were consistent with agronomic analyses of the germplasm and demonstrate
that there should be opportunities to independently manipulate grain number and grain size which is typically difficult due
to strong negative correlations. 相似文献
2.
A new bacterial strain producing succinic acid was enriched from bovine rumen content. It is facultatively anaerobic, belongs
to the family Pasteurellaceae and has similarity to the genus Mannheimia. In batch cultivations with D-glucose or sucrose the strain produced up to 5.8 g succinic acid l−1 with a productivity and a yield of up to 1.5 g l−1 h−1 and 0.6 g g−1, respectively. With crude glycerol up to 8.4 g l−1, 0.9 g l−1 h−1 and 1.2 g g−1 were obtained.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
3.
Identification of QTL underlying isoflavone contents in soybean seeds among multiple environments 总被引:3,自引:0,他引:3
Guoliang Zeng Dongmei Li Yingpeng Han Weili Teng Jian Wang Liquan Qiu Wenbin Li 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,118(8):1455-1463
Soybean isoflavones are valued in certain medicines, cosmetics, foods and feeds. Selection for high-isoflavone content in
seeds along with agronomic traits is a goal of many soybean breeders. The aim of the study was to identify the quantitative
trait loci (QTL) underlying seed isoflavone content in soybean among seven environments in China. A cross was made between
‘Zhongdou 27’, a soybean cultivar with higher mean isoflavone content in the seven environments (daidzein, DZ, 1,865 μg g−1; genistein, GT, 1,614 μg g−1; glycitein, GC, 311 μg g−1 and total isoflavone, TI, 3,791 μg g−1) and ‘Jiunong 20’, a soybean cultivar with lower isoflavone content (DZ, 844 μg g−1; GT, 1,046 μg g−1; GC, 193 μg g−1 and TI, 2,061 μg g−1). Through single-seed-descent, 130 F5-derived F6 recombinant inbred lines were advanced. A total of 99 simple-sequence repeat markers were used to construct a genetic linkage
map. Seed isoflavone contents were analyzed using high-performance liquid chromatography for multiple years and locations
(Harbin in 2005, 2006 and 2007, Hulan in 2006 and 2007, and Suihua in 2006 and 2007). Three QTL were associated with DZ content,
four with GT content, three with GC content, and five with TI content. For all QTL detected the beneficial allele was from
Zhongdou 27. QTL were located on three (DZ), three (GC), four (GT) and five (TI) molecular linkage groups (LG). A novel QTL
was detected with marker Satt144 on LG F that was associated with DZ (0.0014 > P > 0.0001, 5% < R
2 < 11%; 254 < DZ < 552 μg g−1), GT (0.0027 > P > 0.0001; 4% < R
2 < 9%; 262 < GT < 391 μg g−1), and TI (0.0011 > P > 0.0001; 4% < R
2 < 15%; 195 < TI < 871 μg g−1) across the various environments. A previously reported QTL on LG M detected by Satt540 was associated with TI across four
environments and TI mean (0.0022 > P > 0.0001; 3% < R
2 < 8%; 182 < TI < 334 μg g−1) in China. Because both beneficial alleles were from Zhongdou 27, it was concluded that these two QTL would have the greatest
potential value for marker-assisted selection for high-isoflavone content in soybean seed in China.
G. Zeng, D. Li and Y. Han have equal contributions to the paper. 相似文献
4.
Vargas M van Eeuwijk FA Crossa J Ribaut JM 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2006,112(6):1009-1023
The study of QTL × environment interaction (QEI) is important for understanding genotype × environment interaction (GEI) in
many quantitative traits. For modeling GEI and QEI, factorial regression (FR) models form a powerful class of models. In FR
models, covariables (contrasts) defined on the levels of the genotypic and/or environmental factor(s) are used to describe
main effects and interactions. In FR models for QTL expression, considerable numbers of genotypic covariables can occur as
for each putative QTL an additional covariable needs to be introduced. For large numbers of genotypic and/or environmental
covariables, least square estimation breaks down and partial least squares (PLS) estimation procedures become an attractive
alternative. In this paper we develop methodology for analyzing QEI by FR for estimating effects and locations of QTLs and
QEI and interpreting QEI in terms of environmental variables. A randomization test for the main effects of QTLs and QEI is
presented. A population of F2 derived F3 families was evaluated in eight environments differing in drought stress and soil nitrogen content and the traits yield and
anthesis silking interval (ASI) were measured. For grain yield, chromosomes 1 and 10 showed significant QEI, whereas in chromosomes
3 and 8 only main effect QTLs were observed. For ASI, QTL main effects were observed on chromosomes 1, 2, 6, 8, and 10, whereas
QEI was observed only on chromosome 8. The assessment of the QEI at chromosome 1 for grain yield showed that the QTL main
effect explained 35.8% of the QTL + QEI variability, while QEI explained 64.2%. Minimum temperature during flowering time
explained 77.6% of the QEI. The QEI analysis at chromosome 10 showed that the QTL main effect explained 59.8% of the QTL + QEI
variability, while QEI explained 40.2%. Maximum temperature during flowering time explained 23.8% of the QEI. Results of this
study show the possibilities of using FR for mapping QTL and for dissecting QEI in terms of environmental variables. PLS regression
is efficient in accounting for background noise produced by other QTLs. 相似文献
5.
Pools and fluxes of carbon in three Norway spruce ecosystems along a climatic gradient in Sweden 总被引:1,自引:0,他引:1
Dan Berggren Kleja Magnus Svensson Hooshang Majdi Per-Erik Jansson Ola Langvall Bo Bergkvist Maj-Britt Johansson Per Weslien Laimi Truus Anders Lindroth Göran I. Ågren 《Biogeochemistry》2008,89(1):7-25
This paper presents an integrated analysis of organic carbon (C) pools in soils and vegetation, within-ecosystem fluxes and
net ecosystem exchange (NEE) in three 40-year old Norway spruce stands along a north-south climatic gradient in Sweden, measured
2001–2004. A process-orientated ecosystem model (CoupModel), previously parameterised on a regional dataset, was used for
the analysis. Pools of soil organic carbon (SOC) and tree growth rates were highest at the southernmost site (1.6 and 2.0-fold,
respectively). Tree litter production (litterfall and root litter) was also highest in the south, with about half coming from
fine roots (<1 mm) at all sites. However, when the litter input from the forest floor vegetation was included, the difference
in total litter input rate between the sites almost disappeared (190–233 g C m−2 year−1). We propose that a higher N deposition and N availability in the south result in a slower turnover of soil organic matter
than in the north. This effect seems to overshadow the effect of temperature. At the southern site, 19% of the total litter
input to the O horizon was leached to the mineral soil as dissolved organic carbon, while at the two northern sites the corresponding
figure was approx. 9%. The CoupModel accurately described general C cycling behaviour in these ecosystems, reproducing the
differences between north and south. The simulated changes in SOC pools during the measurement period were small, ranging
from −8 g C m−2 year−1 in the north to +9 g C m−2 year−1 in the south. In contrast, NEE and tree growth measurements at the northernmost site suggest that the soil lost about 90 g C m−2 year−1.
An erratum to this article can be found at 相似文献
6.
Plant and soil carbon accumulation following fire in Mediterranean woodlands in Spain 总被引:1,自引:0,他引:1
We measured plant and soil carbon (C) storage following canopy-replacing wildfires in woodlands of northeastern Spain that
include an understory of shrubs dominated by Quercus coccifera and an overstory of Pinus halepensis trees. Established plant succession models predict rapid shrub recovery in these ecosystems, and we build on this model by
contrasting shrub succession with long-term C storage in soils, trees, and the whole ecosystem. We used chronosequence and
repeated sampling approaches to detect change over time. Aboveground plant C increased from <100 to ~3,000 g C m−2 over 30 years following fire, which is substantially less than the 5,942 ± 487 g C m−2 (mean ±1 standard error) in unburned sites. As expected, shrubs accumulated C rapidly, but the capacity for C storage in
shrubs was <600 g C m−2. Pines were the largest plant C pool in sites >20 years post fire, and accounted for all of the difference in plant C between
older burned sites and unburned sites. In contrast, soil C was initially higher in burned sites (~4,500 g C m−2) than in unburned sites (3,264 ± 261 g C m−2) but burned site C declined to unburned levels within 10 years after fire. Combining these results with prior research suggests
two states for C storage. When pine regeneration is successful, ~9,200 g C m−2 accumulate in woodlands but when tree regeneration fails (due to microclimatic stress or short fire return intervals), ecosystem
C storage of ~4,000 g C m−2 will occur in the resulting shrublands. 相似文献
7.
Deepa Dhital Yuichiro Yashiro Toshiyuki Ohtsuka Hibiki Noda Yoko Shizu Hiroshi Koizumi 《Journal of plant research》2010,123(4):519-530
The ecosystem carbon budget was estimated in a Japanese Zoysia japonica grassland. The green biomass started to grow in May and peaked from mid-July to September. Seasonal variations in soil CO2 flux and root respiration were mediated by changes in soil temperature. Annual soil CO2 flux was 1,121.4 and 1,213.6 g C m−2 and root respiration was 471.0 and 544.3 g C m−2 in 2007 and 2008, respectively. The root respiration contribution to soil CO2 flux ranged from 33% to 71%. During the growing season, net primary production (NPP) was 747.5 and 770.1 g C m−2 in 2007 and 2008, respectively. The biomass removed by livestock grazing (GL) was 122.1 and 102.7 g C m−2, and the livestock returned 28.2 and 25.6 g C m−2 as fecal input (FI) in 2007 and 2008, respectively. The decomposition of FI (DL, the dry weight loss due to decomposition)
was very low, 1.5 and 1.4 g C m−2, in 2007 and 2008. Based on the values of annual NPP, soil CO2 flux, root respiration, GL, FI, and DL, the estimated carbon budget of the grassland was 1.7 and 22.3 g C m−2 in 2007 and 2008, respectively. Thus, the carbon budget of this Z. japonica grassland ecosystem remained in equilibrium with the atmosphere under current grazing conditions over the 2 years of the
study. 相似文献
8.
Mucor indicus can be used to produce ethanol from a variety of sugars, including pentose’s. An extract of it, produced by autolysis, could
replace yeast extract in culture medium with improved production of ethanol. At 10 g l−1, the extract gave a higher ethanol yield (0.47 g g−1) and productivity (0.71 g l−1 h−1) compared to medium containing yeast extract (yield 0.45 g g−1; productivity 0.67 g l−1 h−1). 相似文献
9.
Tarek Daas Mourad Younsi Ouided Daas-Maamcha Patrick Gillet Patrick Scaps 《Helgoland Marine Research》2011,65(2):165-173
The polychaete Nereis falsa Quatrefages, 1866 is present in the area of El Kala National Park on the East coast of Algeria. Field investigations were
carried out from January to December 2007 to characterize the populations’ reproductive cycle, secondary production and dynamics.
Reproduction followed the atokous type, and spawning occured from mid-June to the end of August/early September when sea temperature
was highest (20–23°C). The diameter of mature oocytes was approximately 180 μm. Mean lifespan was estimated to about one year.
In 2007, the mean density was 11.27 ind. m−2 with a minimum of 7.83 ind. m−2 in April and a maximum of 14.5 ind. m−2 in February. The mean annual biomass was 1.36 g m−2 (fresh weight) with a minimum of 0.86 g m−2 in December and a maximum of 2.00 g m−2 in June. The population consisted of two cohorts distinguishable from size frequency distributions. One cohort corresponded
to the recruitment of 2006 and the other appeared during the study period in September 2007. The annual production of N. falsa was 1.45 g m−2 year−1, and the production/biomass ratio was 1.07 year−1. 相似文献
10.
Mendes FS González-Pajuelo M Cordier H François JM Vasconcelos I 《Applied microbiology and biotechnology》2011,92(3):519-527
In this work, the production of 1,3-propanediol from glucose and molasses was studied in a two-step process using two recombinant
microorganisms. The first step of the process is the conversion of glucose or other sugar into glycerol by the metabolic engineered
Saccharomyces cerevisiae strain HC42 adapted to high (>200 g l−1) glucose concentrations. The second step, carried out in the same bioreactor, was performed by the engineered strain Clostridium acetobutylicum DG1 (pSPD5) that converts glycerol to 1,3-propanediol. This two-step strategy led to a flexible process, resulting in a 1,3-propanediol
production and yield that depended on the initial sugar concentration. Below 56.2 g l−1 of sugar concentration, cultivation on molasses or glucose showed no significant differences. However, at higher molasses
concentrations, glycerol initially produced by yeast could not be totally converted into 1,3-propanediol by C. acetobutylicum and a lower 1,3-propanediol overall yield was observed. In our hand, the best results were obtained with an initial glucose
concentration of 103 g l−1, leading to a final 1,3-propanediol concentration of 25.5 g l−1, a productivity of 0.16 g l−1 h−1 and 1,3-propanediol yields of 0.56 g g−1 glycerol and 0.24 g g−1 sugar, which is the highest value reported for a two-step process. For an initial sugar concentration (from molasses) of
56.2 g l−1, 27.4 g l−1 of glycerol were produced, leading to 14.6 g l−1 of 1.3-propanediol and similar values of productivity, 0.15 g l−1 h−1, and overall yield, 0.26 g g−1 sugar. 相似文献
11.
A novel application of a continuous flow incubation system (CFIS) was used to assess four phosphorus (P) inactivation agents—alum,
Phoslock™, a new modified zeolite (Z2G1 or Aqual-P™), and allophone—when used as sediment capping agents to manage internal
P loads in lakes. The CFIS technique allowed combined efficacy and sustainability assessment, including: (1) flux measurements
during simulation of stratified (anoxic) and mixed (aerobic) conditions on the same sediment through multiple cycles to assess
the longevity of a range of product doses; (2) simulation of a summer algal bloom collapse and subsequent burial of the products;
and (3) investigation of non-target effects on nitrification and denitrification processes at the sediment–water interface.
Minimum P-removal dose rates were found to differ substantially at 80 g m−2 for alum, 190 g m−2 for Z2G1, 220 g m−2 for allophane and 280 g m−2 for Phoslock™, for similar capping layer thickness of about 2 mm, and would be effective for at least 4 years. All products
temporarily suppressed nitrification and denitrification under aerobic conditions, and it may be important to minimise product
application to any permanently aerobic zones, such as the littoral areas of a lake. While the aluminium (Al)-based products
did not enhance Al fluxes in the CFIS, lanthanum (La) was released at a near constant rate of around 2 mg La m−2 day−1 from the Phoslock™ treatments over a period of at least 14 days. Spatial variability of sediment P, bioturbation, and burial
are factors that will affect up-scaling these results to a whole lake. 相似文献
12.
Sphagnum, the main genus which forms boreal peat, is strongly affected by N and S deposition and raised temperature, but the physiological
mechanisms behind the responses are largely unknown. We measured maximum photosynthetic rate (NPmax), maximum efficiency of photosystem II [variable fluorescence (F
v)/maximum fluorescence yield (F
m)] and concentrations of N, C, chlorophyll and carotenoids as responses to N and S addition and increased temperature in Sphagnum balticum (a widespread species in the northern peatlands) in a 12-year factorial experiment. NPmax did not differ between control (0.2 g N m−2 year−1) and high N (3.0 g N m−2 year−1), but was higher in the mid N treatment (1.5 g N m−2 year−1). N, C, carotenoids and chlorophyll concentration increased in shoot apices after N addition. F
v/F
m did not differ between N treatments. Increased temperature (+3.6°C) had a small negative effect on N concentration, but had
no significant effect on NPmax or F
v/F
m. Addition of 2 g S m−2 year−1 showed a weak negative effect on NPmax and F
v/F
m. Our results suggest a unimodal response of NPmax to N addition and tissue N concentration in S. balticum, with an optimum N concentration for photosynthetic rate of ~13 mg N g−1. In conclusion, high S deposition may reduce photosynthetic capacity in Sphagnum, but the negative effects may be relaxed under high N availability. We suggest that previously reported negative effects
on Sphagnum productivity under high N deposition are not related to negative effects on the photosynthetic apparatus, but differences
in optimum N concentration among Sphagnum species may affect their competitive ability under different N deposition regimes. 相似文献
13.
This article reviews historical changes in the total phosphorus (TP) inputs to Loch Leven, Scotland, UK. Data derived from
palaeolimnological records suggest that inputs in the early 1900s were about 6 t TP year−1 (0.45 g TP m−2 year−1). By 1985, this had risen to about 20 t TP year−1 (1.5 g TP m−2 year−1) due to increases in runoff from agricultural land and discharges from point sources. By the late 1970s, increased TP inputs
were causing serious degradation of lake water quality. Most noticeably, there had been an increase in cyanobacterial blooms.
A catchment management plan was implemented in the early 1990s. This resulted in a 60% reduction in the annual TP input between
1985 (20 t TP year−1/1.5 g TP m−2 year−1) and 1995 (8 t TP year−1/0.6 g TP m−2 year−1). The main reduction was associated with better control of point source discharges, but attempts were also made to reduce
inputs from diffuse sources. The reduction in external TP loading to the lake led to a marked decline in TP retention by the
lake each year. 相似文献
14.
Raúl Muñoz María Hernández Ana Segura Joao Gouveia Antonia Rojas Juan Luis Ramos Santiago Villaverde 《Applied microbiology and biotechnology》2009,83(1):189-198
The long-term performance and stability of Pseudomonas putida mt-2 cultures, a toluene-sensitive strain harboring the genes responsible for toluene biodegradation in the archetypal plasmid
pWW0, was investigated in a chemostat bioreactor functioning under real case operating conditions. The process was operated
at a dilution rate of 0.1 h−1 under toluene loading rates of 259 ± 23 and 801 ± 78 g m−3 h−1 (inlet toluene concentrations of 3.5 and 10.9 g m−3, respectively). Despite the deleterious effects of toluene and its degradation intermediates, the phenotype of this sensitive
P. putida culture rapidly recovered from a 95% Tol− population at day 4 to approx. 100% Tol+ cells from day 13 onward, sustaining elimination capacities of 232 ± 10 g m−3 h−1 at 3.5 g Tol m−3 and 377 ± 13 g m−3 h−1 at 10.9 g Tol m−3, which were comparable to those achieved by highly tolerant strains such as P. putida DOT T1E and P. putida F1 under identical experimental conditions. Only one type of Tol− variant, harboring a TOL-like plasmid with a 38.5 kb deletion (containing the upper and meta operons for toluene biodegradation), was identified. 相似文献
15.
Liu J Zhang Z Liu Z Zhu H Dang H Lu J Cui Z 《Marine biotechnology (New York, N.Y.)》2011,13(5):837-844
The aim of this work was to optimize the fermentation parameters in the shake-flask culture of marine bacterium Wangia sp. C52 to increase cold-adapted amylase production using two statistical experimental methods including Plackett–Burman
design, which was applied to find the key ingredients for the best medium composition, and response surface methodology, which
was used to determine the optimal concentrations of these components. The results showed starch, tryptone, and initial pH
had significant effects on the cold-adapted amylase production. A central composite design was then employed to further optimize
these three factors. The experimental results indicated that the optimized composition of medium was 6.38 g L−1 starch, 33.84 g L−1 tryptone, 3.00 g L−1 yeast extract, 30 g L−1 NaCl, 0.60 g L−1 MgSO4 and 0.56 g L−1 CaCl2. The optimized cultivation conditions for amylase production were pH 7.18, a temperature of 20°C, and a shaking speed of
180 rpm. Under the proposed optimized conditions, the amylase experimental yield (676.63 U mL−1) closely matched the yield (685.60 U mL−1) predicted by the statistical model. The optimization of the medium contributed to tenfold higher amylase production than
that of the control in shake-flask experiments. 相似文献
16.
Rose C. Kaggwa Anne A. van Dam John S. Balirwa Frank Kansiime Patrick Denny 《Wetlands Ecology and Management》2009,17(3):257-277
The processes driving primary productivity and its impacts on fish production were investigated in field trials in eight seasonal
earthen wetland ponds ‘Fingerponds’ (192 m2) in Uganda between 2003 and 2005. The ponds were stocked by the seasonal flood with predominantly Oreochromis spp. at densities ranging from 0.1 to 0.5 fish m−2. Chicken manure (521, 833 or 1,563 kg ha−1) was applied fortnightly. Results showed that primary productivity was enhanced with maximum average net primary productivity
(±Standard Error) of 11.7 (±2.5) g O2 m−2 day−1 at the Gaba site and 8.3 (±1.5) g O2 m−2 day−1 at the Walukuba site. Net fish yields were higher in manured ponds with up to 2,670 kg ha−1 yield for a 310 day growth period compared to less than 700 kg ha−1 in unmanured ponds. Fish production was limited mainly by high recruitment, falling water levels, light limitation from high
suspended solids and turbidity, and low zooplankton biomass. It was concluded that Fingerponds have a high potential for sustainable
fish production and can contribute to the alleviation of protein shortages amongst the riparian communities around Lake Victoria.
Production can be enhanced further with improved stock management. 相似文献
17.
A simulation model for nitrogen retention in a papyrus wetland near Lake Victoria,Uganda (East Africa) 总被引:1,自引:0,他引:1
A. A. van Dam A. Dardona P. Kelderman F. Kansiime 《Wetlands Ecology and Management》2007,15(6):469-480
Papyrus wetlands around Lake Victoria, East Africa play an important role in the nutrient flows from the catchment to the
lake. A dynamic model for nitrogen cycling was constructed to understand the processes contributing to nitrogen retention
in the wetland and to evaluate the effects of papyrus harvesting on the nitrogen absorption capacity of the wetlands. The
model had four layers: papyrus mat, water, sludge and sediment. Papyrus growth was modelled as the difference between nitrogen
uptake and loss. Nitrogen uptake was modelled with a logistic equation combined with a Monod-type nitrogen limitation. Nitrogen
compartments were papyrus plants, organic material in the floating mat; and total ammonia, nitrate and organic nitrogen in
the water, sludge and sediment. Apart from the uptake and decay rates of the papyrus, the model included sloughing and settling
of mat material into the water, mineralization of organic matter, and nitrification and diffusion of dissolved inorganic nitrogen.
Literature data and field measurements were used for parameterization. The model was calibrated with data from Kirinya wetland
in Jinja, Uganda which receives effluent from a municipal wastewater treatment plant. The model simulated realistic concentrations
of dissolved nitrogen with a stable biomass density of papyrus and predicted accumulation of organic sludge in the wetland.
Assuming that this sludge is not washed out of the wetland, the overall nitrogen retention of the wetland over a three-year
period was 21.5 g N m−2 year−1 or about 25% of input. Harvesting 10, 20 and 30% of the papyrus biomass per year increased nitrogen retention capacity of
the wetland to 32.3, 36.8 and 38.1 g m−2 year−1, respectively. Although the nutrient flows estimated by the model are within the ranges found in other papyrus wetlands,
the model could be improved with regard to the dynamics of detrital nitrogen. Actual net retention of nitrogen in the sludge
is likely to be lower than 21.5 g N m−2 year−1 because of flushing out of the sludge to the lake during the rainy season. 相似文献
18.
Chia-Hung Su Liang-Jung Chien James Gomes Yu-Sheng Lin Yuan-Kun Yu Jhang-Song Liou Rong-Jhih Syu 《Journal of applied phycology》2011,23(5):903-908
Reserve lipids of microalgae are promising for biodiesel production. However, optimization of cultivation conditions for both
biomass yield and lipid production of microalgae is a contradictory problem because required conditions for both targets are
different. In this study, a two-stage cultivation strategy is proposed to enhance lipid production of the microalga Nannochloropsis oculata. Biomass growth and lipid production were carried out in two separate and non-interacting stages. In first-stage cultivation,
microalgae were cultivated in optimal conditions for cell growth. Then, microalgae were harvested and transferred into a growth-limited
environment, thus enhancing lipid production of microalgae. Here, optimization of the lipid production stage (second stage)
with respect to different levels of inoculum concentration, salinity of culture broth, and intensity of irradiance was performed.
The results show that irradiance exhibits a significant influence on lipid production. The highest lipid productivity of 0.324 g L−1 day−1 was obtained with an inoculum concentration of 2.3 g L−1, a salinity of 35 g L−1, and an irradiance of 500 μmol photons m−2 s−1. The final yield of lipid obtained from the two-stage process was 2.82-times higher than that from traditional single-stage
batch cultivation systems. 相似文献
19.
A spiral packed-bed bioreactor inoculated with microorganisms obtained from activated sludge was used to conduct a feasibility
study for phenol removal. The reactor was operated continuously at various phenol loadings ranging from 53 to 201.4 g m−3 h−1, and at different hydraulic retention times (HRT) in the range of 20–180 min to estimate the performance of the device. The
results indicated that phenol removal efficiency ranging from 82.9 to 100% can be reached when the reactor is operated at
an HRT of 1 h and a phenol loading of less than 111.9 g m−3 h−1. At an influent phenol concentration of 201.4 g m−3, the removal efficiency increased from 18.6 to 76.9% with an increase in the HRT (20–120 min). For treatment of phenol in
the reactor, the maximum biodegradation rate (V
m) was 1.82 mg l−1 min−1; the half-saturation constant (K
s), 34.95 mg l−1. 相似文献
20.
Waldemar Rymowicz Alina R. Fatykhova Svetlana V. Kamzolova Anita Rywińska Igor G. Morgunov 《Applied microbiology and biotechnology》2010,87(3):971-979
Yarrowia lipolytica A-101-1.22 produces high citric acid (112 g l−1) with a yield of 0.6 g g−1 and a productivity of 0.71 g l−1 h−1 during batch cultivation in the medium with glycerol-containing waste of biodiesel industry. However, it was observed that
the specific citric acid production rate, which was maximal at the beginning of the biosynthesis, gradually decreases in the
late production phase and it makes continuation of the process over 100 h pointless. The cell recycle and the repeated batch
regimes were performed as ways for prolongation of citric acid synthesis by yeast. Using cell recycle, the active citric acid
biosynthesis (96–107 g l−1) with a yield of 0.64 g g−1 and a productivity of 1.42 g l−1 h−1 was prolongated up to 300 h. Repeated batch culture remained stable for over 1000 h; the RB variant of 30% feed every 3 days
showed the best results: 124.2 g l-1 citric acid with a yield of 0.77 g g-1 and a productivity of 0.85 g l-1 h-1. 相似文献