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1.
The endogenous concentrations of the essential elements Ca, Cl, Cu, Fe, K, Mg, Mn, N, P and Zn, and of the nonessential elements Al, As, Ba, Br, Co, Cr, Cs, Hg, I, La, Na, Rb, Sb, Sc, Si and Sr were determined in 5 successive needle age classes. 40 mature spruce trees from 6 different sites were investigated individually. A given element usually shows smooth changes with the needle age class t. Trees on a given site usually have a similar dynamic behaviour. The same holds for the different site means. The concentrations can be approximated by functions c=f(t). Three different types of functions are required to describe the dynamic behaviour of 3 groups of elements that increase with t, and one for the elements that decrease with t. A given element usually can be described by the same type of function at all sites, even if its concentration differs widely. Exceptions are Mn, Co and Zn, which change from a decreasing function at low concentrations to an increasing function at high concentrations. Further irregulatities are found at some sites with Ca, Sr and Ba. These findings are corroborated by a multivariate statistical analysis. 相似文献
2.
The concentrations of Fe, Zn and Co were determined in up to five successive needle age classes in 54 individual Norway spruce
trees from eight different sites (soil pH 3.1–7.7). Fe concentrations (12–25 μg in needles from the current year) were lower
than most published values, due to the removal of surface contamination prior to analysis. Fe showed a significant positive
correlation with Al. Successive needle age classes either had constant values or showed an increase for Fe concentrations;
individual trees on a given site were rather uniform in their behaviour. Zn concentrations were 19–40 μg/g. On acid sites,
they showed a positive correlation with total soil concentrations. The majority of trees showed decreasing Zn concentrations
in successive needle age classes, but constant or increasing concentrations were also found; site homogeneity was less than
with Fe. Co concentrations differed between trees on a neutral soil (12 ng/g) and on acid soils (41–174 ng/g). They showed
a significant positive correlation with Mn needle concentrations. The changes of Co with needle age in most, but not all,
trees were similar to those of Zn. The different changes of Fe, Zn and Co with needle age may be due to a different retranslocation.
A modest retranslocation of Fe as opposed to a high retranslocation of Zn and Co (in most trees) is consistent with the observed
behaviour.
Received: 10 May 1999 / Accepted: 8 September 1999 相似文献
3.
Armin Wyttenbach Sixto Bajo Jürg Bucher Verena Furrer Patrick Schleppi Leonhard Tobler 《Trees - Structure and Function》1995,10(1):31-39
The concentrations of Ca, Sr, Ba and Mn were determined in up to five successive needle age classes from 54 individual Norway spruce trees [Picea abies (L.) Karst] from nine different sites. The accumulation behaviour was found to be very nonuniform, going from an increase with needle age to a decrease; irregular patterns were also found. The type of accumulation is largely site specific. The increasing behaviour can in most cases be approximated by a simple arithmetic function. All four elements usually show the same accumulation pattern, the similarities being closest between Ca and Mn and least between Ca and Ba. It is postulated that the similarity between the four elements is due to their precipitation and storage as oxalates. The similarity between Ca, Sr and Ba is observed at all concentrations, that with Mn only at concentrations larger than 300 g/g. Mn at small concentrations (< 50 g/g) shows a decreasing pattern and no similarity at all with Ca, Sr and Ba, but behaves similar to mobile elements. 相似文献
4.
Guevara SR Bubach D Macchi PJ Vigliano P Arribére M Colombo JC 《Biological trace element research》2006,111(1-3):97-119
The ratios of Rb to Cs contents were studied in five fish species from seven lakes located in the Patagonia Andean Range,
Argentina in order to trace fish diet. The species studied were native velvet catfish (Diplomistes viedmensis) and creole perch (Percichthys trucha), and exotic brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss), and brook trout (Salvenilus fontinalis). Rainbow trout specimens from two farms were also studied, as well as fish food items and native mussels (Diplodon chilensis). Rb and Cs concentrations were determined by instrumental neutron activation analysis. A positive correlation of Cs concentration
in the muscle of velvet catfish with fish length was observed, probably associated with the long biological half-life of this
element in this species, whereas the Rb concentration remained constant, hence inhibiting the use of Rb-Cs ratios as a tracer
in this case. Seasonal variations observed for rainbow trout and Cs concentration background bias in one of the lakes studied
are also a limiting factor to the use of Rb-Cs ratios as a diet tracer. Rb-Cs ratios allowed clear differentiation of rainbow
trout raised in farms from the natural specimens that lived in the same environment, in agreement with Rb-Cs ratios determined
in both diets. Rb-Cs ratios in rainbow trout showed significant differences between Rivadavia and Futalaufquen lakes compared
to Moreno and Nahuel Huapi lakes, which could be associated with a higher participation of plankton in the diet in the first
case. No relevant variations in Rb-Cs ratios of brown trout were observed, probably because of the similarity in the diet. 相似文献
5.
Dae-Sung Lee Min-Seung Kang Hye-Jin Hwang Sung-Hwan Eom Ji-Young Yang Myung-Suk Lee Won-Jae Lee You-Jin Jeon Jae-Sue Choi Young-Mog Kim 《Biotechnology and Bioprocess Engineering》2008,13(6):758-764
We have been attempting for some time to discover a compound evidencing antibacterial activity against methicillin-resistant
Staphylococcus aureus (MRSA). The dieckol isolated from Ecklonia stolonifera has been shown to exhibit antibacterial activity against methicillin-susceptible S. aureus (MSSA) and MRSA. The minimum inhibitory concentrations (MICs) of dieckol were determined in a range of 32 to 64 μg/mL against
standard MSSA and MRSA strains. Furthermore, dieckol clearly reversed the high-level ampicillin and penicillin resistance
of MRSA. The MICs of ampicillin against two standard strains of MRSA were dramatically reduced from 512 to 0.5 μg/mL in combination
with 1/4 MIC of dieckol (16 μg/mL). The fractional inhibitory concentration (FIC) indices of ampicillin and penicillin were
measured from 0.066 to 0.266 in combination with 8 or 16 μg/mL of dieckol against all tested MRSA strains, thereby suggesting
that dieckol-ampicillin or dieckol-penicillin combinations exert a synergistic effect against MRSA. The results of this study
indicate that dieckol, administered in combination with β-lactams, may prove effective in the treatment of MRSA infections.
Our finding may also contribute to the development of an alternative phytotherapeutic anti-MRSA agent. 相似文献
6.
Field experiments in the high rainfall zone (HRZ) and the medium rainfall zone (MRZ) in Zambia were designed to determine
the natural occurrence of fumonisins (FB1–2) in Zambian maize hybrids, accumulation of FB1–2 resulting from artificial inoculation with Fusarium verticillioides and effects of climate and planting time on FB1–2 in maize. Combined FB1–2 concentrations varied from 0 to 13,050 ng/g, with an overall mean of 666 ng/g. Maize from the HRZ had low incidences of FB1–2-positive samples (mean 41%) which contained FB1–2 below 500 ng/g. In the MRZ, higher incidences (mean 97%) and concentrations (40% of samples >1,000 ng/g) were recorded in
two out of three years. There was no correlation between mean location FB1–2 concentrations in individual years and precipitation, number of rain days or monthly precipitation. Postponing the planting
time with 10 or 20 days did not significantly affect FB1–2 concentration, but it reduced the yields in some years. 相似文献
7.
S. M. Ghaderian A. Mohtadi R. Rahiminejad R. D. Reeves A. J. M. Baker 《Plant and Soil》2007,293(1-2):91-97
Serpentine soils, which contain relatively high concentrations of nickel and some other metals, are the preferred substrate
for some plants, especially those that accumulate Ni in their tissues. In temperate regions more Ni-hyperaccumulator plants
are found in Alyssum than in any other genus. In this study, serpentine soils of two areas (Marivan and Dizaj) in the west/northwest of Iran and
also perennial Alyssum plants growing on these soils were analyzed for Ni and some other metals. The highest concentrations of total metals in the
soils of these areas for Ni, Cr, Co and Mn were 1,350, 265, 94 and 1,150 μg g−1, respectively, while concentrations of Fe, Mg and Ca reached 3.55%, 16.8% and 0.585% respectively. The concentration of exchangeable
Ni in these soils is up to 4.5 μg g−1. In this study two Alyssum species, A. inflatum and A. longistylum, have been collected from Marivan and Dizaj, respectively. Analysis of leaf dry matter shows that they can contain up to
3,700 and 8,100 μg Ni g−1, respectively. This is the first time that such high Ni concentrations have been found in these species. The concentrations
of other metals determined in these species were in the normal range for serpentine plants, except for Ca, which was higher,
up to 5.3% and 3.5%, respectively 相似文献
8.
Spatial and age-dependent tree-ring growth responses of Larix gmelinii to climate in northeastern China 总被引:2,自引:0,他引:2
Tree-ring width chronologies from 276 Larix gmelinii cores taken in northeastern China were used to analyze spatial and age-dependent growth–climate response relationships. Tree
radial growth from five localities showed similar patterns, while exhibiting different tree-ring growth responses to local
climate. The rotated principal component analysis (RPCA) indicated that tree age, growing season moisture conditions, and
ambient air temperature variations resulted from location differences (e.g., longitude, latitude, and altitude), which could
explain the non-stationary spatial climate–growth relations observed. The study tested the fundamental assumption that the
climate–growth of L. gmelinii was age independent after the removal of size trends and disturbance signals. The age-related climate–growth relationship
might potentially improve the veracity of past climate reconstructions. Bootstrapped correlation function analyses suggested
that the response of L. gmelinii radial growth to climate differed between trees ≥150 years old and <150 years old. Mean sensitivity and standard deviation
for trees increased with age in the <150 years old tree class; whereas trees ≥150 years old had no significant relationship
with age. These results showed that the assumption of age-independent climate–growth relationship is invalid at these sites.
Physiological processes and/or hydraulic constraints dependent on tree age, together with detrending techniques could be the
possible causal factors of clear age-dependent responses. These results suggested the importance of incorporating trees of
all ages into the chronology to recover a detailed climatic signal in a reconstruction of L. gmelinii for this region. 相似文献
9.
Light-saturated net photosynthesis (Asat), dark respiration (RD), and foliar nutrient content of eight European Scots pine (Pinus sylvestris L.) provenances were measured at experimental sites in western Poland. Two-year-old seedlings were planted in 1984 at two sites with similar soils in areas of contrasting air pollution. One site was near a point source of SO2 and other pollutants, and another 12 km to the southeast in an area free of acute air pollution was treated as a control. The eight provenances were from a large north-tosouth latitudinal range (60 to 43° N). At the heavily polluted site Scots pine trees exhibited lower growth rates and crown dieback and deformation. Soil pH, Ca and Mg were at least 10 times lower, and Al 10 times higher at the polluted than the control site. In 1991, concentrations of Al, P, Ca, S, Mn, Fe, and Zn in oneyear old Scots pine foliage were higher and Mg lower at the polluted than control site. At both sites foliar Mg levels were within the range considered deficient (0.6 mg g-1), and at the polluted site, Al concentrations were very high (670 to 880 g g-1). In all provenances, RD of one-year-old needles was higher (by 22% on average) and Asat was lower (by 37% on average) at the polluted than the control site. The ratio of Asat: RD was half as great in all provenances at the polluted (4 to 6) than control site (8 to 11). Provenances of southern origin had greater increases in RD and water-use efficiency at the polluted site than other provenances. Within the polluted site alone, or across both sites, Asat in Scots pine was negatively correlated to the Al: Ca ratio (p<0.001, r=–0.93). Across sites RD increased with needle N and Al (multiple regression, p<0.001). The data suggest that at the polluted site there is excessive soil Al and deficient Mg availability, low needle Mg and high Al concentrations and high Al: Ca ratios, and that these have resulted in reduced photosynthetic capacity and increased respiration. 相似文献
10.
Ben Bond-Lamberty Stith T. Gower Chuankuan Wang Pascal Cyr Hugo Veldhuis 《Biogeochemistry》2006,81(1):1-16
This study examined the nitrogen (N) dynamics of a black spruce (Picea mariana (Mill.) BSP)-dominated chronosequence in Manitoba, Canada. The seven sites studied each contained separate well- and poorly drained stands, originated from stand-killing wildfires, and were between 3 and 151 years old. Our goals were to (i) measure total N concentration ([N]) of all biomass components and major soil horizons; (ii) compare N content and select vegetation N cycle processes among the stands; and (iii) examine relationships between ecosystem C and N cycling for these stands. Vegetation [N] varied significantly by tissue type, species, soil drainage, and stand age; woody debris [N] increased with decay state and decreased with debris size. Soil [N] declined with horizon depth but did not vary with stand age. Total (live + dead) biomass N content ranged from 18.4 to 99.7 g N m−2 in the well-drained stands and 37.8–154.6 g N m−2 in the poorly drained stands. Mean soil N content (380.6 g N m−2) was unaffected by stand age. Annual vegetation N requirement (5.9 and 8.4 g N m−2 yr−1 in the middle-aged well- and poorly drained stands, respectively) was dominated by trees and fine roots in the well-drained stands, and bryophytes in the poorly drained stands. Fraction N retranslocated was significantly higher in deciduous than evergreen tree species, and in older than younger stands. Nitrogen use efficiency (NUE) was significantly lower in bryophytes than in trees, and in deciduous than in evergreen trees. Tree NUE increased with stand age, but overall stand NUE was roughly constant (∼
∼150 g g−1 N) across the entire chronosequence. 相似文献
11.
Several matrix-attachment regions (MARs) from animals have been shown to block interactions between an enhancer and promoter
when situated between the two. Since a similar function for plant MARs has not been discerned, we tested the Zea mays
ADH1 5′ MAR, Nicotiana tabacum
Rb7 3′ MAR and a transformation booster sequence (TBS) MAR from Petunia hybrida for their ability to impede enhancer–promoter interactions in Arabidopsis thaliana. Stable transgenic lines containing vectors in which one of the three MAR elements or a 4 kb control sequence were interposed
between the cauliflower mosaic virus
35S enhancer and a flower-specific AGAMOUS second intron-derived promoter (AGIP)::β-glucuronidase (GUS) fusion were assayed for GUS expression in vegetative tissues. We demonstrate that the TBS MAR element, but not the ADH1 or Rb7 MARs, is able to block interactions between the 35S enhancer and AGIP without compromising the function of either with elements from which they are not insulated.
Accession numbers: TBS from Petunia hybrida cultivar V26, GenBank accession number EU864306. 相似文献
12.
Summary The concentrations of 23 elements have been determined by instrumental neutron activation analysis in the needles and axes of 1-year-old spruce twigs from 12 different sites. Although the twigs had been washed with toluene and tetrahydrofuran prior to analysis, it was found that the amounts of eight elements (Al, Cr, Eu, Fe, La, Sc, Th and V) present were predominantly due to aerosol particles still being retained on the surface of the axes. The results of the remaining 15 elements (Ba, Br, Ca, Cl, Co, Cs, Hg, K, Mg, Mn, Na, P, Rb, Sr and Zn) were not or only slightly influenced by this effect and are considered to represent their inherent concentrations within the axes. With most of these latter 15 elements there are highly significant and linear correlations between the concentrations in the needles and in the axis, which testify to the great similarity of needles and axis of a twig. The axis/needles ratios are constant for every element (except K), but the individual elements show considerable differentiation, as evidenced by their ratios, which have values between 0.5 and 2.8. Inter-element correlations in the axes are mainly found within two groups of elements. With Na, Cl and Br these correlations are probably due to different pollution levels of the different sites, whereas with Mn, Co, Rb and Cs they are due to the pH of the soil. The activity of 137Cs from the Chernobyl fallout represents independent confirmation of the results obtained with the stable elements. With twigs sprouted before the deposition of the fallout, 137Cs acts as a tracer for aerosol particles, whereas it forms a tracer for the stable Cs inherent to the plant with twigs sprouted after the deposition. 相似文献
13.
A frequently desired outcome when rehabilitating Zn toxic sites in Australia is to establish a self-sustaining native ecosystem. Hence, it is important to understand the tolerance of Australian native plants to high concentrations of Zn. Very little is known about the responses of Australian native plants, and trees in particular, to toxic concentrations of Zn. Acacia holosericea, Eucalyptus camaldulensis and Melaleuca leucadendra plants were grown in dilute solution culture for 10 weeks. The seedlings (42 days old) were exposed to six Zn treatments viz., 0.5, 5, 10, 25, 50 and 100 M. The order of tolerance to toxic concentrations of Zn was E. camaldulensis> A. holosericea> M. leucadendra, the critical external concentrations being approximately 20, 12 and 1.5 M, respectively. Tissue Zn concentrations increased as solution Zn increased for all species. Root tissue concentrations were higher than shoot tissue concentrations at all solution Zn concentrations. The critical tissue Zn concentrations were approximately 85 and 110 g g–1 DM for M. leucadendra, 115 and 155 g g–1 DM for A. holosericea and 415 and 370 g g–1 DM for E. camaldulensis for the youngest fully expanded leaf and total shoots, respectively. The results from this paper provide the first comprehensive combination of growth responses, critical external concentrations, critical tissue concentrations and plant toxicity symptoms for three important Australian genera, viz., Eucalyptus, Acacia and Melaleuca, for use in the rehabilitation of potentially Zn toxic sites. 相似文献
14.
Plant samples collected from 17 populations of 9 taxa of the generaDianthus, Minuartia, Scleranthus, andSilene (Caryophyllaceae), growing in 14 metalliferous sites of N Greece, and surface soil samples from their growth area were analysed for Cu, Pb, Zn, Cd, Ni, Cr, Fe, Mn, Ca, Mg. Metal uptake varies considerably between the populations. A resistance mechanism excluding Cu and Pb from the aerial parts of the plants over a wide range of the soil concentrations up to a critical soil level appeared to exist, whereas Zn concentrations in plants were analogously related to those of the soil.Scleranthus perennis subsp.perennis showed the highest Cu concentration (205 µg/g), whereasMinuartia cf.bulgarica hyperaccumulated Pb (1175 µg/g). Ca concentrations in plants were in most cases much higher than those in soil, whereas the contrary was true for Mg. As a result the Ca/Mg ratio, which was in almost all cases lower than 1 in the soil, was much increased in the plants. 相似文献
15.
Leader dieback associated with B deficiency in P. radiata D. Don plantations was treated with borax applied at rates of 50, 100 and 150 kg ha−1. This initially increased B in foliage from 5 to 40, 80 and 110 μg g−1 respectively, and was followed by a rapid decline and stabilisation at around 25 μg g−1 for the duration of the study. Annual fluctuations in foliage B levels were strongly correlated with rainfall during the
preceding spring and summer. Uptake of N, P and K increased as a result of applied B and comparison of the distribution of
these nutrients in crowns of fertilized and unfertilised trees six years after application indicated continued uptake of these
nutrients probably as a result of improved root growth due to B. Foliage concentrations of B like N, P and K, increased in
young needles towards the upper crown and this, together with a decline in needle concentrations of B as foliage aged, indicated
some redistribution of B from older to new foliage. A limit of 5 μg g−1 was found below which little redistribution seems to occur.
Application of B prevented further leader dieback, improved apical dominance and height growth and increased volume production
by 25 m3 ha−1 at age 8 years. Differences between application rates of B were not significant in terms of growth. 相似文献
16.
Damayanti De Ananda Mukhopadhyay Ranadhir Chakraborty 《World journal of microbiology & biotechnology》2008,24(11):2727-2729
Enterobacter sp. was isolated from the diseased and dead caterpillars of the tea leaf roller (Caloptilia theivora) from the Darjeeling foothill region. When the vegetative form of the bacterium was applied via food, mortality of C. theivora showed an LC50 value at 363.1 μg/ml (bacterial wt./vol. of water) with fiducial limits 363.25 and 362.94 μg/ml respectively. The LT50 values for C. theivora were 6 days for 100 μg/ml, 5.96 days for 300 μg/ml, 5.81 days for 500 μg/ml, 4.96 days for 750 μg/ml and 4.61 days for 1,000 μg/ml
concentrations. The finding would enable one to contemplate development of a microbial pesticide using this novel Enterobacter sp. DD01 for control of the leaf rolling pest. 相似文献
17.
Charles R. Warren 《Trees - Structure and Function》2006,20(2):157-164
Rates of photosynthesis vary with foliage age and typically decline from full-leaf expansion until senescence occurs. This age-related decline in photosynthesis is especially important in species that retain foliage for several years, yet it is not known whether the internal conductance to CO2 movement (g
i) plays any role. More generally, g
i has been measured in only a few conifers and has never been measured in leaves or needles older than 1 year. The effect of ageing on g
i was investigated in Pinus pinaster, a species that retains needle for 4 or more years. Measurements were made in autumn when trees were not water limited and after leaf expansion was complete. Rates of net photosynthesis decreased with needle age, from 8 μmol m−2 s−1 in fully expanded current-year needles to 4.4 μmol m−2 s−1 in 3-year-old needles. The relative limitation due to internal conductance (0.24–0.35 out of 1) was in all cases larger than that due to stomatal conductance (0.13–0.19 out of 1). Internal conductance and stomatal conductance approximately scaled with rates of photosynthesis. Hence, there was no difference among year-classes in the relative limitations posed by internal and stomatal conductance or evidence that they cause the age-related decline in photosynthesis. There was little evidence that the age-related decline in photosynthesis was due to decreases in contents of N or Rubisco. The decrease in rates of photosynthesis from current-year to older needles was instead related to a twofold decrease in rates of photosynthesis per unit nitrogen and V
cmax/Rubisco (i.e., in vivo specific activity). 相似文献
18.
Horiguchi T Ohta Y Nishikawa T Shiraishi F Shiraishi H Morita M 《Cell biology and toxicology》2008,24(6):553-562
To clarify how tributyltin (TBT) and triphenyltin (TPT) interact with the retinoid X receptor (RXR) to induce growth of male
sex organs in female gastropods, we treated female rock shells (Thais clavigera) with three different concentrations (0.1, 1, or 5 μg/g wet wt) of 9-cis-retinoic acid (9CRA) or with a single concentration (1 μg/g wet wt) of TBT, TPT, or fetal bovine serum (as a control). The
effects of each treatment were measured as the incidence of imposex, the length of the penis-like structure, and the vas deferens
sequence (VDS) index. 9CRA induced imposex in a dose-dependent manner; imposex incidence was significantly higher in the rock
shells that received 1 (P < 0.05) or 5 μg (P < 0.001) 9CRA than in the controls. After 1 month, the rock shells treated with 5 μg 9CRA exhibited substantial growth of
the penis-like structure that was not as evident in the other treated shells. The length of the structure differed between
the 0.1- and 5-μg 9CRA treatment groups (P < 0.05) but not between the 1- and 5-μg 9CRA treatment groups (P > 0.05). Compared with the control, the VDS index increased significantly in the 1- (P < 0.05) and 5-μg (P < 0.001) 9CRA groups. The penis-like structures behind the right tentacle in female rock shells treated with 5 μg 9CRA were
essentially the same as the penises and vasa deferentia of normal males and of TBT-treated or TPT-treated imposexed females.
These results further support the hypothesis that imposex in gastropods could be mediated by RXR. 相似文献
19.
Sharon M. L. Ewe Evelyn E. Gaiser Daniel L. Childers David Iwaniec Victor H. Rivera-Monroy Robert R. Twilley 《Hydrobiologia》2006,569(1):459-474
We present here a 4-year dataset (2001–2004) on the spatial and temporal patterns of aboveground net primary production (ANPP)
by dominant primary producers (sawgrass, periphyton, mangroves, and seagrasses) along two transects in the oligotrophic Florida
Everglades coastal landscape. The 17 sites of the Florida Coastal Everglades Long Term Ecological Research (FCE LTER) program
are located along fresh-estuarine gradients in Shark River Slough (SRS) and Taylor River/C-111/Florida Bay (TS/Ph) basins
that drain the western and southern Everglades, respectively. Within the SRS basin, sawgrass and periphyton ANPP did not differ
significantly among sites but mangrove ANPP was highest at the site nearest the Gulf of Mexico. In the southern Everglades
transect, there was a productivity peak in sawgrass and periphyton at the upper estuarine ecotone within Taylor River but
no trends were observed in the C-111 Basin for either primary producer. Over the 4 years, average sawgrass ANPP in both basins
ranged from 255 to 606 g m−2 year−1. Average periphyton productivity at SRS and TS/Ph was 17–68 g C m−2 year−1 and 342–10371 g C m−2 year−1, respectively. Mangrove productivity ranged from 340 g m−2 year−1 at Taylor River to 2208 g m−2 year−1 at the lower estuarine Shark River site. Average Thalassia testudinum productivity ranged from 91 to 396 g m−2 year−1 and was 4-fold greater at the site nearest the Gulf of Mexico than in eastern Florida Bay. There were no differences in periphyton
productivity at Florida Bay. Interannual comparisons revealed no significant differences within each primary producer at either
SRS or TS/Ph with the exception of sawgrass at SRS and the C−111 Basin. Future research will address difficulties in assessing
and comparing ANPP of different primary producers along gradients as well as the significance of belowground production to
the total productivity of this ecosystem. 相似文献
20.
Domínguez-Bocanegra AR Ponce-Noyola T Torres-Muñoz JA 《Applied microbiology and biotechnology》2007,75(4):783-791
Phaffia rhodozyma (now Xanthophyllomyces dendrorhous) and Haematococcus pluvialis are known as the major prominent microorganisms able to synthesize astaxanthin natural pigment. Important research efforts
have been made to determine optimal conditions for astaxanthin synthesis. When the focus is on astaxanthin production, the
maximal reported value of 9.2 mg/g cell is obtained within H. pluvialis grown on BAR medium, under continuous illumination (345 μmol photon m−2 s−1) and without aeration. Whereas fermentation by mutated R1 yeast grown on coconut milk produced 1,850 μg/g yeast. However,
when looking at astaxanthin productivity, the picture is slightly different. The figures obtained with P. rhodozyma are rather similar to those of H. pluvialis. Maximal reported values are 170 μg/g yeast per day with a wild yeast strain and 370 μg/g yeast per day with mutated R1 yeast.
In the case of H. pluvialis, maximal values ranged from 290 to 428 μg/g cell per day depending on the media (BG-11 or BAR), light intensity (177 μmol
photon m−2 s−1), aeration, etc. The main aim of this work was to examine how astaxanthin synthesis, by P. rhodozyma and H. pluvialis, could be compared. The study is based on previous works by the authors where pigment productions have been reported. 相似文献