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2.
The response of the aquatic plant Sparganium emersum to different sediment nutrient levels was studied in three mesocosm experiments. The aim was to assess plant growth parameters
and nutrient accumulation in the plant tissue under conditions relevant for habitats with sediments affected by anthropogenic
nutrient enrichment. The experimental treatments were produced by fertilisation of the rooting medium (washed river sand)
with differing doses of either NPK mineral fertiliser or digested sludge from solid pig slurry waste. Growth inhibition by
high nutrient levels was not observed in any treatment (highest nutrient concentrations in the sediment with mineral fertiliser:
N 250 mg kg−1, P 50 mg kg−1; organic fertiliser: N 6300 mg kg−1, P 1800 mg kg−1), which confirms the tolerance of S. emersum to high nutrient loads. The sediment nutrient concentration was best reflected in shoot dry mass. Nutrient contents in plant
tissues were similar for most nutrient concentrations in the rooting media; only N increased significantly with N levels in
the sediment in belowground parts. Nutrient standing stocks in plants, however, generally corresponded to the nutrient supply,
and reached highest values (max. N 3.7 g m−2, P 1.2 g m−2) in the richest treatments with organic fertiliser. The capability of S. emersum to use nutrients from high sediment concentrations and in organically polluted environments recommends this species for use
in water quality management including tertiary wastewater treatment. 相似文献
3.
P. W. Inglett E. M. D’Angelo K. R. Reddy P. V. McCormick S. E. Hagerthey 《Wetlands Ecology and Management》2009,17(2):131-144
The use of periphyton nitrogenase activity (biological N2 fixation) as an indicator of wetland P impact was assessed using patterns of nutrient content (C, N, P, Ca, Mg, K, Fe, and
Mn) and acetylene reduction (AR) in floating cyanobacterial periphyton mat (metaphyton) communities of a P-enriched portion
of the Florida Everglades, USA (Water Conservation Area-2A, WCA-2A). Spatial patterns of nutrients indicate the enrichment
of floating mat periphyton N, P, Fe, and K, and the reduction of Mn and TN:TP in enriched marsh areas. In highly enriched
areas, floating mat periphyton AR was approximately threefold greater than that in less enriched, interior marsh zones. Multiple
regression models indicated AR dependence on P in eutrophic WCA-2A areas while the AR of more interior marsh periphyton mats
was more closely related to tissue levels of Ca and Fe. Nitrogenase activity of floating mat periphyton from P-loaded mesocosms
revealed a significant enhancement of N2 fixation in samples receiving approximately 2–3 mg P m−2 of cumulative P dosing or with biomass TP content of 100–300 mg kg−1. At P contents above the optimum, mat periphyton AR was suppressed possibly as a result of changes in species composition
or increased levels of NH4+. After 3 years of dosing, consistently high AR occurred only at low rates of P enrichment (0.4–0.8 g P m−2 yr−1), and the patterns appeared to be seasonal. These findings agree with the hypothesis that P availability is a key determinant
of nitrogenase activity in aquatic systems, and thus, may support the use of periphyton nitrogenase to indicate P impacts
in P-limited systems. These results also demonstrate the potential existence of a P threshhold for biogeochemical alteration
of periphyton mat function in the Everglades, and that cumulative loading of limiting nutrients (i.e., P), rather than instantaneous
concentrations, should be considered when evaluating nutrient criteria. 相似文献
4.
Characterization of phosphorus fractions in the sediments of a tropical intertidal mangrove ecosystem 总被引:2,自引:0,他引:2
Solid phases of phosphorus fractions in the surface and core sediments were studied to understand the biogeochemical cycling
and bioavailability of phosphorus in the Pichavaram intertidal mangrove sediments of India. Total P in surface and core sediments
ranged between 451–552 and 459–736 μg g−1 respectively and Fe bound P was the dominant fraction. Low levels of Fe bound P in the mangrove zone than the two estuarine
zones may be because of high salinity inhibition of phosphate adsorption onto the Fe-oxides/hydroxides. Post-depositional
reorganization of P was observed in surface sediments, converting organic P and Fe bound P into the authigenic P. High levels
of organic P in the mangrove zone is primarily due to intensive cycling and degradation of organic matter and adsorption of
phosphate on the organic molecules. The burial rates and regeneration efficiency of P in the intertidal mangrove ecosystem
ranged from 5.41 to 7.27 μmol P cm−2 year−1 and 0.122 to 0.233 μmol P cm−2 year−1, respectively. High burial efficiency (≈99%) of P proves the earlier observation of limiting nature of P for the biological
productivity. Further, bioavailable P (exchangeable P + Fe bound P + organic P) constituted a considerable proportion of sedimentary
P pool of which an average accounted for 55 and 50% in surface and core sediments respectively. The results indicate that
significant amount of P is locked in sediments in the form of authigenic P and detrital P which makes P as a limiting nutrient
for the biological productivity. 相似文献
5.
Edward Castañeda-Moya Robert R. Twilley Victor H. Rivera-Monroy Brian D. Marx Carlos Coronado-Molina Sharon M. L. Ewe 《Ecosystems》2011,14(7):1178-1195
Patterns of mangrove vegetation in two distinct basins of Florida Coastal Everglades (FCE), Shark River estuary and Taylor
River Slough, represent unique opportunities to test hypotheses that root dynamics respond to gradients of resources, regulators,
and hydroperiod. We propose that soil total phosphorus (P) gradients in these two coastal basins of FCE cause specific patterns
in belowground biomass allocation and net primary productivity that facilitate nutrient acquisition, but also minimize stress
from regulators and hydroperiod in flooded soil conditions. Shark River basin has higher P and tidal hydrology with riverine
mangroves, in contrast to scrub mangroves of Taylor basin with more permanent flooding and lower P across the coastal landscape.
Belowground biomass (0–90 cm) of mangrove sites in Shark River and Taylor River basins ranged from 2317 to 4673 g m−2, with the highest contribution (62–85%) of roots in the shallow root zone (0–45 cm) compared to the deeper root zone (45–90 cm).
Total root productivity did not vary significantly among sites and ranged from 407 to 643 g m−2 y−1. Root production in the shallow root zone accounted for 57–78% of total production. Root turnover rates ranged from 0.04
to 0.60 y−1 and consistently decreased as the root size class distribution increased from fine to coarse roots, indicating differences
in root longevity. Fine root biomass was negatively correlated with soil P density and frequency of inundation, whereas fine
root turnover decreased with increasing soil N:P ratios. Lower P availability in Taylor River basin relative to Shark River
basin, along with higher regulator and hydroperiod stress, confirms our hypothesis that interactions of stress from resource
limitation and long duration of hydroperiod account for higher fine root biomass along with lower fine root production and
turnover. Because fine root production and organic matter accumulation are the primary processes controlling soil formation
and accretion in scrub mangrove forests, root dynamics in the P-limited carbonate ecosystem of south Florida have a major
controlling role as to how mangroves respond to future impacts of sea-level rise. 相似文献
6.
Masahiko Hirata Nobumi Hasegawa Maki Nomura Haruko Ito Kangoro Nogami Tatsunobu Sonoda 《Ecological Research》2009,24(1):119-125
This study monitored deposition and decomposition of cattle dung in a grazed young Chamaecyparis obtusa (an evergreen conifer) plantation in southwestern Japan, as a part of exploring the impacts of livestock in the forest grazing
system. Animals defecated 10–19 times hd−1 day−1, producing feces of 2.2–3.5 kg DM and 33–73 g N per animal per day. The DM and N concentrations of feces ranged from 157–207 g DM kg−1 and 14.8−23.1 g (kg DM)−1, respectively. Occurrence of defecation was spatially heterogeneous, with feces being concentrated mainly on areas for resting
(forest roads, ridges and valleys) and moving (forest roads and along fence lines). Decomposition of dung pats was considerably
slow, showing the rates of 1.37–3.05 mg DM (g DM)−1 day−1 as DM loss. Decomposition was further slower on the basis of N release, 0.51–1.63 mg N (g N)−1 day−1, resulting in steadily increased N concentrations of dung pats with time after deposition. The results show that introduction
of livestock into a forest (i.e., forest grazing) may limit nutrient availability to plants, by redistributing nutrients into
areas with no vegetation (bare land and streams) and by establishing a large N pool as feces due to an imbalance between deposition
and slow release, though further studies are necessary for investigating the occurrence of slow dung decomposition in other
forest situations. 相似文献
7.
Photosynthetic performance in Sphagnum transplanted along a latitudinal nitrogen deposition gradient 总被引:1,自引:1,他引:0
Gustaf Granath Joachim Strengbom Angela Breeuwer Monique M. P. D. Heijmans Frank Berendse Håkan Rydin 《Oecologia》2009,159(4):705-715
Increased N deposition in Europe has affected mire ecosystems. However, knowledge on the physiological responses is poor.
We measured photosynthetic responses to increasing N deposition in two peatmoss species (Sphagnum balticum and Sphagnum fuscum) from a 3-year, north–south transplant experiment in northern Europe, covering a latitudinal N deposition gradient ranging
from 0.28 g N m−2 year−1 in the north, to 1.49 g N m−2 year−1 in the south. The maximum photosynthetic rate (NPmax) increased southwards, and was mainly explained by tissue N concentration, secondly by allocation of N to the photosynthesis,
and to a lesser degree by modified photosystem II activity (variable fluorescence/maximum fluorescence yield). Although climatic
factors may have contributed, these results were most likely attributable to an increase in N deposition southwards. For S. fuscum, photosynthetic rate continued to increase up to a deposition level of 1.49 g N m−2 year−1, but for S. balticum it seemed to level out at 1.14 g N m−2 year−1. The results for S. balticum suggested that transplants from different origin (with low or intermediate N deposition) respond differently to high N deposition.
This indicates that Sphagnum species may be able to adapt or physiologically adjust to high N deposition. Our results also suggest that S. balticum might be more sensitive to N deposition than S. fuscum. Surprisingly, NPmax was not (S. balticum), or only weakly (S. fuscum) correlated with biomass production, indicating that production is to a great extent is governed by factors other than the
photosynthetic capacity. 相似文献
8.
Impact of long-term nitrogen addition on carbon stocks in trees and soils in northern Europe 总被引:4,自引:2,他引:2
The aim of this study was to quantify the effects of fertiliser N on C stocks in trees (stems, stumps, branches, needles,
and coarse roots) and soils (organic layer +0–10 cm mineral soil) by analysing data from 15 long-term (14–30 years) experiments
in Picea abies and Pinus sylvestris stands in Sweden and Finland. Low application rates (30–50 kg N ha−1 year−1) were always more efficient per unit of N than high application rates (50–200 kg N ha−1 year−1). Addition of a cumulative amount of N of 600–1800 kg N ha−1 resulted in a mean increase in tree and soil C stock of 25 and 11 kg (C sequestered) kg−1 (N added) (“N-use efficiency”), respectively. The corresponding estimates for NPK addition were 38 and 11 kg (C) kg−1 (N). N-use efficiency for C sequestration in trees strongly depended on soil N status and increased from close to zero at
C/N 25 in the humus layer up to 40 kg (C) kg−1 (N) at C/N 35 and decreased again to about 20 kg (C) kg−1 (N) at C/N 50 when N only was added. In contrast, addition of NPK resulted in high (40–50 kg (C) kg−1 (N)) N-use efficiency also at N-rich (C/N 25) sites. The great difference in N-use efficiency between addition of NPK and
N at N-rich sites reflects a limitation of P and K for tree growth at these sites. N-use efficiency for soil organic carbon
(SOC) sequestration was, on average, 3–4 times lower than for tree C sequestration. However, SOC sequestration was about twice
as high at P. abies as at P. sylvestris sites and averaged 13 and 7 kg (C) kg−1 (N), respectively. The strong relation between N-use efficiency and humus C/N ratio was used to evaluate the impact of N
deposition on C sequestration. The data imply that the 10 kg N ha−1 year−1 higher deposition in southern Sweden than in northern Sweden for a whole century should have resulted in 2.0 ± 1.0 (95% confidence
interval) kg m−2 more tree C and 1.3 ± 0.5 kg m−2 more SOC at P. abies sites in the south than in the north for a 100-year period. These estimates are consistent with differences between south
and north in tree C and SOC found by other studies, and 70–80% of the difference in SOC can be explained by different N deposition. 相似文献
9.
Denitrification efficiency for defining critical loads of carbon in shallow coastal ecosystems 总被引:2,自引:2,他引:0
Denitrification efficiency [DE; (N2 − N/(DIN + N2 − N) × 100%)] as an indicator of change associated with nutrient over-enrichment was evaluated for 22 shallow coastal ecosystems
in Australia. The rate of carbon decomposition (which can be considered a proxy for carbon loading) is an important control
on the efficiency with which coastal sediments in depositional mud basins with low water column nitrate concentrations recycle
nitrogen as N2. The relationship between DE and carbon loading is due to changes in carbon and nitrate (NO3) supply associated with sediment biocomplexity. At the DE optimum (500–1,000 μmol m−2 h−1), there is an overlap of aerobic and anaerobic respiration zones (caused primarily by the existence of anaerobic micro-niches
within the oxic zone, and oxidized burrow structures penetrating into the anaerobic zone), which enhances denitrification
by improving both the organic carbon and nitrate supply to denitrifiers. On either side of the DE optimum zone, there is a
reduction in denitrification sites as the sediment loses its three-dimensional complexity. At low organic carbon loadings,
a thick oxic zone with low macrofauna biomass exists, resulting in limited anoxic sites for denitrification, and at high carbon
loadings, there is a thick anoxic zone and a resultant lack of oxygen for nitrification and associated NO3 production. We propose a trophic scheme for defining critical (sustainable) carbon loading rates and possible thresholds
for shallow coastal ecosystems based on the relationship between denitrification efficiency and carbon loading for 17 of the
22 Australian coastal ecosystems. The denitrification efficiency “optimum” occurs between carbon loadings of about 50 and
100 g C m−2 year−1. Coastal managers can use this simple trophic scheme to classify the current state of their shallow coastal ecosystems and
for determining what carbon loading rate is necessary to achieve any future state.
Guest editors: J. H. Andersen & D. J. Conley
Eutrophication in Coastal Ecosystems: Selected papers from the Second International Symposium on Research and Management of
Eutrophication in Coastal Ecosystems, 20–23 June 2006, Nyborg, Denmark 相似文献
10.
Akiko Sasaki Yu Hagimori Ichiro Yuasa Takayuki Nakatsubo 《Landscape and Ecological Engineering》2012,8(1):107-114
To quantify organic matter mineralization at estuarine intertidal flats, we measured in situ sediment respiration rates using
an infrared gas analyzer in estuarine sandy intertidal flats located in the northwestern Seto Inland Sea, Japan. In situ sediment
respiration rates showed spatial and seasonal variations, and the mean of the rates is 38.8 mg CO2-C m−2 h−1 in summer. In situ sediment respiration rates changed significantly with sediment temperature at the study sites (r
2 = 0.70, p < 0.05), although we did not detect any significant correlations between the rates and sediment characteristics. We prepared
a model for estimating the annual sediment respiration based on the in situ sediment respiration rates and their temperature
coefficient (Q
10 = 1.8). The annual sediment respiration was estimated to be 92 g CO2-C m−2 year−1. The total amount of organic carbon mineralization for the entire estuarine intertidal flats through sediment respiration
(43 t C year−1) is equivalent to approximately 25% of the annual organic carbon load supplied from the river basin of the estuary. 相似文献
11.
Summary Four cyanobacterial inoculants all significantly increased grain and straw yield of rice either alone or in combination with
chemical fertilizer. A saving of 25 kg N ha−1 can be attained through cyanobacterial fertilization. Tobacco waste-based cyanobacterial biofertilizer was best in performance.
Cyanobacterial acetylene reducing activity in vivo varied from 144 to 255 μmol C2H4 m−2 h−1 in different treatments, being highest for tobacco-based cyanobacterial biofertilizer integrated with 50% chemical N. The
nutrient balance for total N, available N, total P and available P was found positive in biofertilizer- and chemical fertilizer-treated
plots. The total and available K showed negative balance in all the treatments. The shelf-life of cyanobacterial biofertilizer
can be augmented by selecting translucent packing material, dry mixing and paddy straw as a carrier. Dry mixing and a mixing
ratio of 50:50 (carrier:cyanobacteria) gave better inoculum loading and shelf-life. Decrease in cyanobacterial population
was least in dried cyanobacterial flacks, indicating a possibility of developing cyanobacterial biofertilizer without carrier
mixing at the time of production. 相似文献
12.
Rhamnolipid biosurfactant production by Pseudomonas nitroreducens isolated from petroleum-contaminated soil was investigated. The effects of carbon, nitrogen and carbon to nitrogen ratio
on biosurfactant production were examined using mineral salts medium as the growth medium. The tenso-active properties (surface
activity and critical micelle concentrations of the produced biosurfactant were also evaluated. The best carbon source, nitrogen
source were glucose and sodium nitrate giving rhamnolipid yields of 5.28 and 4.38 g l−1, respectively. The maximum rhamnolipid production of 5.46 g l−1 was at C/N (glucose/sodium nitrate) of 22. The rhamnolipid biosurfactant reduced the surface tension of water from 72 to
~37 mN/m. It also has critical micelle concentration of ~28 mg l−1. Thus, the results presented in our reports show that the produced rhamnolipid can find wide applications in various bioremediation
activities such as enhanced oil recovery and petroleum degradation. 相似文献
13.
Catabolic diversity of periphyton and detritus microbial communities in a subtropical wetland 总被引:1,自引:0,他引:1
The catabolic diversity of wetland microbial communities may be a sensitive indicator of nutrient loading or changes in environmental
conditions. The objectives of this study were to assess the response of periphyton and microbial communities in water conservation
area-2a (WCA-2a) of the Everglades to additions of C-substrates and inorganic nutrients. Carbon dioxide and CH4 production rates were measured using 14 days incubation for periphyton, which typifies oligotrophic areas, and detritus,
which is prevalent at P-impacted areas of WCA-2a. The wetland was characterized by decreasing P levels from peripheral to
interior, oligotrophic areas. Microbial biomass and N mineralization rates were higher for oligotrophic periphyton than detritus.
Methane production rates were also higher for unamended periphyton (80 mg CH4-C kg−1 d−1) than detritus (22 mg CH4-C kg−1 d−1), even though the organic matter content was higher for detritus (80%) than periphyton (69%). Carbon dioxide production for
unamended periphyton (222 mg CO2-C kg−1 d−1) was significantly greater than unamended detritus (84 mg CO2-C kg−1 d−1). The response of the heterotrophic microbial community to added C-substrates was related to the nutrient status of the wetland,
as substrate-induced respiration (SIR) was higher for detritus than periphyton. Amides and polysaccharides stimulated SIR
more than other C-substrates, and methanogenesis was greater contributor to SIR for periphyton than detritus. Inorganic P
addition stimulated CO2 and CH4 production for periphyton but not detritus, indicating a P limitation in the interior areas of WCA-2a. Continued nutrient
loading into oligotrophic areas of WCA-2a or enhanced internal nutrient cycling may stimulate organic matter decomposition
and further contribute to undesirable changes to the Everglades ecosystem caused by nutrient enrichment. 相似文献
14.
Banana plantlets (Musa acuminata cv Grande Naine) cultivated in hydroponics take up silicon proportionally to the concentration of Si in the nutrient solution
(0–1.66 mM Si). Here we study the Si status of banana plantlets grown under controlled greenhouse conditions on five soils
developed from andesitic volcanic ash, but differing in weathering stage. The mineralogical composition of soils was inferred
from X-ray diffraction, elemental analysis and selective chemical/mineralogical extractions. With increasing weathering, the
content of weatherable primary minerals decreased. Conversely, clay content increased and stable secondary minerals were increasingly
dominant: gibbsite, Fe oxides, allophane, halloysite and kaolinite. The contents of biogenic Si in plant and soil were governed
by the reserve of weatherable primary minerals. The largest concentrations of biogenic Si in plant (6.9–7 g kg−1) and soil (50–58 g kg−1) occurred in the least weathered soils, where total Si content was above 225 g kg−1. The lowest contents of biogenic Si in plant (2.8–4.3 g kg−1) and soil (8–31 g kg−1) occurred in the most weathered desilicated soils enriched with secondary oxides and clay minerals. Our data imply that soil
weathering stage directly impacted the soil-to-plant transfer of silicon, and thereby the stock of biogenic Si in a soil–plant
system involving a Si-accumulating plant. They further imply that soil type can influence the silicon soil–plant cycle and
its hydrological output. 相似文献
15.
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
16.
This study was designed to identify rhizobial strains specific to greengram expressing higher tolerance against insecticides,
fipronil and pyriproxyfen, and synthesizing plant growth regulators even amid insecticide-stress. Of the 50 bradyrhizobial
isolates, the Bradyrhizobium sp. strain MRM6 showed tolerance up to 1,600 μg mL−1 against each of fipronil and pyriproxyfen. The tolerant Bradyrhizobium sp. (vigna) produced plant growth promoting substances in substantial amounts, both in the presence and absence of insecticides. The
strain MRM6 was further used to investigate its impact on greengram grown in soils treated with 200 (the recommended dose),
400 and 600 μg kg−1 soil of fipronil and 1,300 (the recommended dose), 2,600 and 3,900 μg kg−1 soil of pyriproxyfen. Fipronil at 600 μg kg−1 soils and pyriproxyfen at 3,900 μg kg−1 soils had greatest toxic effects and decreased plant biomass, symbiotic efficiency, nutrient uptake and seed yield of greengram
plants. The Bradyrhizobium sp. (vigna) inoculant when used with fipronil and pyriproxyfen significantly increased the measured parameters compared to the plants
grown in soils treated solely with the same concentration of each insecticide. This study inferred that the Bradyrhizobium sp. (vigna) strain MRM6 may be exploited as bio-inoculant to increase the productivity of greengram exposed to insecticide-stressed
soils. 相似文献
17.
Kim YS Lee JH Kim NH Yeom SJ Kim SW Oh DK 《Applied microbiology and biotechnology》2011,90(2):489-497
In the fed-batch culture of glycerol using a metabolically engineered strain of Escherichia coli, supplementation with glucose as an auxiliary carbon source increased lycopene production due to a significant increase in
cell mass, despite a reduction in specific lycopene content. l-Arabinose supplementation increased lycopene production due to increases in cell mass and specific lycopene content. Supplementation
with both glucose and l-arabinose increased lycopene production significantly due to the synergistic effect of the two sugars. Cell growth by the
consumption of carbon sources was related to endogenous metabolism in the host E. coli. Supplementation with l-arabinose stimulated only the mevalonate pathway for lycopene biosynthesis and supplementation with both glucose and l-arabinose stimulated synergistically only the mevalonate pathway. In the fed-batch culture of glycerol with 10 g l−1 glucose and 7.5 g l−1
l-arabinose, the cell mass, lycopene concentration, specific lycopene content, and lycopene productivity after 34 h were 42 g l−1, 1,350 mg l−1, 32 mg g cells−1, and 40 mg l−1 h−1, respectively. These values were 3.9-, 7.1-, 1.9-, and 11.7-fold higher than those without the auxiliary carbon sources,
respectively. This is the highest reported concentration and productivity of lycopene. 相似文献
18.
The nematophagous fungus Pochonia chlamydosporia (Clavicipitaceae) and entomopathogenic fungus Beauveria bassiana (Cordycipitaceae) have great potential for biological control. However, a significant barrier to their commercial development
as mycopesticides is the high costs associated with production. Carbon (C) concentration and C to nitrogen ratio (C:N ratio)
greatly affect fungal growth and sporulation. Effects of C concentration and C:N ratio differed when the fungi were cultivated
using two different methods: the conventional (continuous cultivation) method and a novel “two-stage” method. Sporulation
of P.
chlamydosporia (HSY-12-14) was the highest when the media contained 6 g l−1 C and a C:N ratio of 40:1 or 8 g l−1 C and C:N ratios of 20:1 or 40:1 for the conventional method but 8 g l−1 C and a C:N ratio of only 10:1 with the novel “two-stage” method. Sporulation of B. bassiana (IBC1201) was the highest when the media contained 12 g l−1 C and a C:N ratio of 40:1 with the conventional method but only 4 g l−1 C and a C:N ratio of 5:1 with the novel “two-stage” method. In addition, the nutritional requirements as determined by the
conventional method differed for mycelial growth and sporulation. Understanding the effects of nutrition on sporulation can
help programs seeking to use these organisms as biological control agents and is essential for their mass production and commercialization. 相似文献
19.
Changhua Hu Yi Zou Wenting Zhao 《World journal of microbiology & biotechnology》2009,25(10):1705-1711
Effect of soybean oil on mycelial biomass and pleuromutilin biosynthesis by Pleurotus mutilis-04 was investigated in shake flask culture. The maximum pleuromutilin production and mycelial biomass were 8.32 ± 0.02 g l−1 and 49.10 ± 1.00 g l−1 when 20 g l−1 soybean oil was fed at 24 and 96 h respectively. A repeated fed-batch fermentation strategy with feeding 3 g l−1 soybean oil from 96 to 144 h at 24 h intervals was developed successfully to maintain mycelial growth and provide abundant
fatty acids for pleuromutilin biosynthesis. Compared with glucose as the sole carbon source, soybean oil was obviously beneficial
for the production of pleuromutilin. The results suggested that manipulation of metabolic regulation by soybean oil was an
effective way to enhance the production pleuromutilin. 相似文献
20.
Susumu S. Abe Takashi Kotegawa Taisuke Onishi Yoshinori Watanabe Toshiyuki Wakatsuki 《Ecological Research》2012,27(1):219-227
This study investigated the influence of mound-building termites on soil particle dynamics on the land surface and in soil-forming
processes by examining the amount of soil particles in mound structures of Macrotermes bellicosus in a highly weathered Ultisol of tropical savanna. Soil particle turnover via the mounds was estimated using particle stock
data and soil turnover data from previous studies. A 4-ha study plot with six mounds of relatively uniform shape and size
was investigated. Soil mass constituting the mounds was 6,166 ± 1,581 kg mound−1 within which the mound wall and nest body accounted for 5,002 ± 1,289 and 1,164 ± 293 kg, respectively. The mound wall contained
a significantly larger amount of clay (252 ± 9.97 g kg−1) balanced with a lower sand content (676 ± 26.5 g kg−1) than in the adjacent surface (Ap1) horizon, (46.4 ± 12.8 g clay kg−1; 866 ± 83.2 g sand kg−1); the nest body had much higher clay content (559 ± 51.0 g kg−1) but less sand (285 ± 79.2 g kg−1) than the mound wall. As a result, the mounds of M. bellicosus accumulated clay of 2,874 ± 781 kg ha−1 (corresponding to 2.52% of clay stock in the Ap1 horizon) along with an estimated clay turnover rate of 169 kg ha−1 year−1. These findings suggest a positive feedback effect from termite mound-building activity on soil particle dynamics in tropical
savanna ecosystems: M. bellicosus preferentially use subsoil material for mound construction, resulting in relocation of illuvial clay in the subsoil to the
land surface where clay eluviation from the surface soil and its illuviation in the subsoil are major soil-forming processes. 相似文献