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1.
The algal growth potential (AGP) in water samples of the Danube wetland waters (1388–1426 r. km) as well as the effect of
nitrogen (in final concentration of 0.16 g l−1) and phosphorus enrichment (in final concentration of 0.02 g l−1) on the AGP was investigated by miniaturized bioassay method. Values of the total biomass of Chlorella kessleri up to the 14th day of incubation were suitable for the evaluation of trophic conditions according to the classification of
AGP. On the basis of the AGP results, trophic conditions in 55% of the samples were oligo-mesotrophic and in 46% of the samples
meso-eutrophic. A statistically significant correlation (r = 0.34) was established between the AGP of C. kessleri in original water samples and NO3 concentrations in situ. The TN/TP ratio in the wetland waters indicated a greater limitation due to nitrogen than phosphorous. Significantly lower
TSITN than TSISD, TSIChla and TSITP indicated nitrogen limited conditions. In order to quantify established nutrient limitation by the bioassay method, the effect
of added N and P concentrations on the growth rate of C. kessleri was expressed as the degree of nutrient limitation (Δr d−1) during 7 days of incubation. In the Danube wetland waters only N limitation was established in June and July; N and P limitation
in May and September while in August and October 2003 neither of the tested nutrients were limiting. From May to October 2003
the significantly highest degree of nitrogen (Δr = 0.736 d−1) and phosphorus limitation (Δr = 0.474 d−1) was determined in Lake Sakadaš. 相似文献
2.
The effects of temperature (20, 24 and 28 °C) and irradiance (15 and 40 μmol photon m−2 s−1) on the nitrate and ammonium uptake rates of the subtropical red alga, Laurencia brongniartii, were investigated to prepare for tank cultivation. Nitrate uptake followed saturation kinetics and was faster at higher
irradiances and temperatures. In contrast, ammonium uptake was linear over the experimental range and was not affected by
an increase in temperature. A parameter, β, was calculated to compare substrate uptake rates of nitrate along the linear portion
of the uptake curve with that of ammonium. For nitrate, β was lower at low irradiance and higher at high irradiance (β = 0.007
± 0.003 and 0.030 ± 0.002 [μmol N L−1 (μmol N gww−1 d−)−1], respectively). However, β was 0.023 ± 0.002 and 0.034 ± 0.002 [μmol N L−1 (μmol N gww−1 d−1)−1] for ammonium, suggesting a preference for ammonium over nitrate. 相似文献
3.
The biokinetics of glucose metabolism were evaluated in Aeromonas hydrophila during growth in an anaerobic biosystem. After approx 34 h growth, A. hydrophila metabolized 5,000 mg glucose l−1 into the end-products ethanol, acetate, succinate and formate. The maximum growth rate, μ
m, half saturation coefficients, K
s, microbial yield coefficient, Y, cell mass decay rate coefficient, k
d, and substrate inhibition coefficient, K
si were 0.25 ± 0.03 h−1, 118 ± 31 mg glucose l−1, 0.12 μg DNA mg glucose−1, 0.01 h−1, and 3,108 ± 1,152 mg glucose l−1, respectively. These data were used to predict the performance of a continuous growth system with an influent glucose concentration
of 5,000 mg l−1. Results of the analysis suggest that A. hydrophila will metabolize glucose at greater than 95% efficiency when hydraulic retention times (HRTs) exceed 7 h, whereas the culture
is at risk of washing out at an HRT of 6.7 h. 相似文献
4.
Summary Cells ofCandida shehatae repressed by growth in glucose- or D-xylose-medium produced a facilitated diffusion system that transported glucose (K
s±2 mM,V
max±2.3 mmoles g−1 h−1),d-xylose (K
s±125 mM,V
max±22.5 mmoles g−1 h−1) and D-mannose, but neither D-galactose norl-arabinose.
Cells derepressed by starvation formed several sugar-proton symports. One proton symport accumulated 3-0-methylglucose about
400-fold and transported glucose (K
s±0.12 mM,V
max ± 3.2 mmoles g−1 h−1) andd-mannose, a second proton symport transportedd-xylose (K
s± 1.0 mM,V
max 1.4 mmoles g−1 h−1) andd-galactose, whilel-arabinose apparently used a third proton symport. The stoicheiometry was one proton for each molecule of glucose or D-xylose
transported. Substrates of one sugar proton symport inhibited non-competitively the transport of substrates of the other symports.
Starvation, while inducing the sugar-proton symports, silenced the facilitated diffusion system with respect to glucose transport
but not with respect to the transport of D-xylose, facilitated diffusion functioning simultaneously with thed-xylose-proton symport. 相似文献
5.
The influence of diet on the growth of Stenonema vicarium (Walker) (Ephemeroptera: Heptageniidae) 总被引:1,自引:1,他引:0
Laboratory studies compared the growth rate of Stenonema vicarium (Walker) nymphs on diets of detritus and natural stream periphyton. In three consecutive runs of the experiment, growth rates
were consistently higher on periphyton (mean growth rate = 2.1% wet wt. d−1) than detritus (mean = 1.8% wet wt. d−1). The starting date of each run also significantly influenced growth rates. In each treatment growth rates generally decreased
over the course of the 3 runs, and ca. one-half of the nymphs in the last run did not molt or grow. It appeared that growth
of S. vicarium may be partially controlled by seasonal factors. 相似文献
6.
Malaysia is the world’s leading producer of palm oil products that contribute US$ 7.5 billion in export revenues. Like any
other agro-based industries, it generates waste that could be utilized as a source of organic nutrients for microalgae culture.
Present investigation delves upon Isochrysis sp. culture in POME modified medium and its utilization as a supplement to Nanochloropsis sp. in rotifer cultures. The culture conditions were optimized using a 1 L photobioreactor (Temp: 23°C, illumination: 180 ∼ 200 μmol
photons m−2s−1, n = 6) and scaled up to 10 L outdoor system (Temp: 26–29°C, illumination: 50 ∼ 180 μmol photons m−2s−1, n = 3). Algal growth rate in photobioreactor (μ = 0.0363 h−1) was 55% higher compared to outdoor culture (μ = 0.0163 h−1), but biomass production was 1.3 times higher in outdoor culture (Outdoor = 91.7 mg m−2d−1; Photobioreactor = 69 mg m−2d−1). Outdoor culture produced 18% higher lipid; while total fatty acids (FA) was not significantly affected by the change in
culture systems as both cultures yield almost similar concentrations of fatty acids per gram of sample (photobioreactor = 119.17 mg
g−1; outdoor culture = 104.50 mg g−1); however, outdoor cultured Isochrysis sp. had 26% more polyunsaturated fatty acids (PUFAs). Rotifers cultured in Isochrysis sp./ Nanochloropsis sp. (1:1, v/v) mixture gave similar growth rate as 100% Nanochoropsis sp. culture (μ = 0.40 d−1), but had 45% higher counts of rotifers with eggs (t = 7, maximum). The Isochrysis sp. culture successfully lowered the nitrate (46%) and orthophosphate (83%) during outdoor culture. 相似文献
7.
Light irradiation had remarkable effects on callus growth of Oldenlandia affinis with an optimum intensity of 35 μmol m−2 s−1. Biosynthesis of kalata B1, the main cyclic peptide in O. affinis, was induced and triggered with rising irradiation intensities. The highest concentration of kalata B1, 0.49 mg g−1 DW characterised by the maximum productivity of 3.88 μg per litre and day was analysed at 120 μmol m−2 s−1, although callus growth was repressed. The light saturation point was established to be 35 μmol m−2 s−1, where kalata B1 productivity was in a similar order (3.41 μg per day) due to the higher growth index. O. affinis suspension cultures were shown to accumulate comparable specific kalata B1 concentrations in a delayed growth associated
production pattern. These were dependent on irradiation intensity (0.16 mg g−1 at 2 μmol m−2 s−1; 0.28 mg g−1 at 35 μmol m−2 s−1). The batch cultivation process resulted in a maximum productivity of 27.30 μg per litre and day with culture doubling times
of 1.16 d−1. Submers operation represented a 8-fold product enhancement compared to callus cultivation. 相似文献
8.
Candida utiilis NRRL Y-900 was grown on pineapple cannery waste as the sole carbon and energy source in a chemostat at dilution rates ranging
between 0.05 and 0.65 h−1 to determine the growth kinetics. The cell yield coefficient varied with dilution rate and a maximum value of 0.662 ± 0.002
gx/gcarb was obtained at a dilution rate of 0.4 h−1. At steady state, the concentrations of carbohydrate, reducing sugar, and chemical oxygen demand (COD) appeared to follow
Monod kinetics. At maximum specific growth rate (μmax) 0.65 h−1, the saturation constants for carbohydrate, reducing sugar and COD were 0.51 ± 0.02 gcarb/1, 0.046 ± 0.003 grs/1, and 1.036 ± 0.001 gCOD/1, respectively. Maximum biomass productivity (Q
x max) 2.8 ± 0.03 gx/1 h was obtained at a dilution rate of 0.5 h−1. At this dilution rate, only 71.0 ± 0.41% COD was removed whereas at a dilution rate of 0.1 h−1, 98.2 ± 0.35% reduction in COD was achieved. At a dilution rate of 0.4 h−1, the optimal yeast productivity and reduction in COD were 2.7 ± 0.13 gp/1 h, and 84.2 ± 0.42%, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Development of two endomycorrhizal symbioses on soybean and comparison with phosphorus fertilization
Summary Soybean (Glycine max L. Merr. cv. Amsoy 71) plants were grown in a greenhouse in a soil very low in plant-available P, and plants were harvested
5 times over a 21-week growth period. Soybeans were inoculated with one of two species of VAM fungi or received daily one
of three nutrient solutions of different P concentrations (0.0, 0.2, or 1.0mMP). Until week 9, the dry weights, leaf areas and developmental stage of soybeans inoculated withG. fasciculatum orG. mosseae were similar to the 1.0 or 0.2mMP-treated plants, respectively. Phosphorus concentrations were significantly lower in VAM plants at weeks 6 and 9 as compared
to non-VAM soybeans given 1.0mMP, suggesting P input in VAM plants was immediately used for new growth. Total P input for VAM plants was linear over 21 weeks,
and the average rate of P uptake for these plants was 0.19mg P d−1. Estimated specific P uptake rates (SPUR) for the mycorrhizae (VAM roots) were twice that of the control (0.0mMP) roots. The calculated SPURs forG. fasciculatum andG. mosseae hyphae were 95 and 120μg P g−1 VAM d−1 respectively, a 4 to 5 fold increase over non-inoculated roots, indicating more attention must be paid to P assimilation
by VAM fungi in P-fixing substrates.
Contribution from the Western Regional Research Center, USDA-ARS (CRIS No. 5325-20580-003). 相似文献
10.
Establishment of in vitro plants, cell and tissue cultures from Oldenlandia affinis for the production of cyclic peptides 总被引:1,自引:1,他引:0
In vitro cultured plants from Oldenlandia affinis were established from seeds and grown on a hormone-free medium. In vitro plants produced the cyclic peptide kalata B1 in concentrations of 0.67 mg g−1 dry weight after growth of 30 days. This was approximately 50% of the concentration analysed in green house plants (shoot tips), where different concentrations have been determined in leaves (1.82 mg g−1), shoot tips (1.36 mg g−1), stems (0.36 mg g−1), and in flowers (0.16 mg g−1). Callus and cell suspension cultures could be initiated from aseptic root, stem and leaf explants of O. affinis seedlings and plants. Different light intensities were shown to affect culture growth as well as chlorophyll synthesis. The friable callus was then used for the establishment of a cell suspension culture. Fresh and dry weight measurements showed that growth was optimal on MS medium supplemented with 0.4 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-d). Leaf suspensions cultured on this medium showed a 4-fold increase of biomass by the first week of incubation. No quantifiable amounts of kalata B1 were produced under these conditions. Morphological differentiation seems to be essential for cyclic peptide production. Therefore, several undifferentiated as well as organised cell lines of O. affinis have been developed. These cell lines will constitute a worthwhile starting point for the optimisation of kalata B1 synthesis in liquid media to the objective of producing cyclic peptides under controlled and defined conditions in bioreactors. 相似文献
11.
J. G. Wakibia J. J. Bolton D. W. Keats L. M. Raitt 《Journal of applied phycology》2006,18(3-5):565-573
As a possible means of improving the livelihoods of local villagers, off-bottom rope cultivation of commercial eucheumoids was investigated on the southern Kenyan coast at three sites, representative of the variety of environments. The morphotypes used were brown Eucheuma denticulatum and green and brown Kappaphycus alvarezii. The study was carried out over a 15 month period from August 2001 until October 2002. Relative growth rates were highest at a sandy flat in a mangrove system (Gazi; 5.6% d−1), and lowest in an intertidal reef flat (Kibuyuni; 3.2% d−1) with a lagoon being intermediate (Mkwiro; 4.8% d−1). The brown E. denticulatum had the highest growth rate of 4.7% d−1 compared to the green and brown K. alvarezii which were 4.3% d−1 and 4.2% d−1, respectively. Growth was more variable at Kibuyuni and Mkwiro. The growth was higher during the southeast monsoon (4.7% d−1) than during the northeast monsoon (4.0% d−1). This is part of a larger study and the effects of water motion, salinity, temperature, thallus nitrogen, and ‘ice-ice’ syndrome on growth of morphotypes is discussed. The water motion was observed to increase thallus nitrogen and hence the growth of eucheumoids. The ‘ice-ice’ condition affected both brown E. denticulatum and brown K. alvarezii but not green K. alvarezii. The results suggest that commercial cultivation of eucheumoids in Kenya will be feasible. 相似文献
12.
Kenchaiah Lohith Balaraman Manohar Soundar Divakar 《World journal of microbiology & biotechnology》2007,23(7):955-964
A kinetic study on esterification between d-glucose and l-phenylalanine catalysed by lipases from Rhizomucor miehei (RML) and Candida rugosa (CRL) in organic media investigated in detail showed that both the lipases followed a Ping-Pong Bi-Bi mechanism with two
distinct types of competitive inhibitions. Graphical double reciprocal plots and computer simulation studies showed that competitive
double substrate inhibition took place at higher concentrations leading to dead-end inhibition in the case of RML and in the
case of CRL, inhibition only by d-glucose at higher concentrations leading to dead-end lipase–d-glucose complexes. An attempt to obtain the best fit of these kinetic models through curve-fitting yielded in good approximation,
the apparent values of important kinetic parameters, RML: k
cat = 2.24 ± 0.23 mM h−1 (mg protein)−1, K
m l-phenylalanine = 95.6 ± 9.7 mM, K
m d-glucose = 80.0 ± 8.5 mM, K
i l-phenylalanine = 90.0 ± 9.2 mM, K
i d-glucose = 13.6 ± 1.42 mM; CRL: k
cat = 0.51 ± 0.06 mM h−1 (mg protein)−1, K
m l-phenylalanine = 10.0 ± 0.98 mM, K
m d-glucose = 6.0 ± 0.64 mM, K
i d-glucose = 8.5 ± 0.81 mM. 相似文献
13.
Van Geest GJ Hessen DO Spierenburg P Dahl-Hansen GA Christensen G Faerovig PJ Brehm M Loonen MJ Van Donk E 《Oecologia》2007,153(3):653-662
A dramatic increase in the breeding population of geese has occurred over the past few decades at Svalbard. This may strongly
impact the fragile ecosystems of the Arctic tundra because many of the ultra-oligotrophic freshwater systems experience enrichment
from goose feces. We surveyed 21 shallow tundra ponds along a gradient of nutrient enrichment based on exposure to geese.
Concentrations of total phosphorus (P) and dissolved inorganic nitrogen (DIN) in the tundra ponds ranged from 2–76 to 2–23 μg l−1 respectively, yet there was no significant increase in phytoplankton biomass (measured as chlorophyll a; range: 0.6–7.3 μg l−1) along the nutrient gradient. This lack of response may be the result of the trophic structure of these ecosystems, which
consists of only a two-trophic level food chain with high biomasses of the efficient zooplankton grazer Daphnia in the absence of fish and scarcity of invertebrate predators. Our results indicate that this may cause a highly efficient
grazing control of phytoplankton in all ponds, supported by the fact that large fractions of the nutrient pools were bound
in zooplankton biomass. The median percentage of Daphnia–N and Daphnia–P content to particulate (sestonic) N and P was 338 and 3009%, respectively, which is extremely high compared to temperate
lakes. Our data suggest that Daphnia in shallow arctic ponds is heavily subsidized by major inputs of energy from other food sources (bacteria, benthic biofilm),
which may be crucial to the persistence of strong top–down control of pelagic algae by Daphnia. 相似文献
14.
Alves L Matos J Tenreiro R Gírio FM 《Journal of industrial microbiology & biotechnology》2008,35(1):69-73
Gordonia alkanivorans strain 1B is able to desulfurize dibenzothiophene (DBT) to 2-hydroxybiphenyl (2-HBP), the final product of the 4S pathway.
However, both the cell growth and the rate of desulfurization can be largely affected by the nutrient composition of the growth
medium due to cofactor requirements of many enzymes involved in the biochemical pathways. In this work, the effect of several
metal ions on the growth and DBT desulfurization by G. alkanivorans was studied. From all the metal ions tested, only the absence of zinc significantly affected the cell growth and the desulfurization
rate. By increasing the concentration of Zn from 1 to 10 mg L−1, 2-HBP productivity was improved by 26%. The absence of Zn2+, when sulfate was also used as the only sulfur source, did not cause any difference in the bacterial growth. Resting cells
grown in the presence of Zn2+ exhibited a 2-HBP specific productivity of 2.29 μmol g−1 (DCW) h−1, 7.6-fold higher than the specific productivity obtained by resting cells grown in the absence of Zn2+ (0.30 μmol g−1 (DCW) h−1). These data suggests that zinc might have a key physiological role in the metabolism of DBT desulfurization. 相似文献
15.
Matteo Campioli Roeland Samson Anders Michelsen Sven Jonasson Robert Baxter Raoul Lemeur 《Plant Ecology》2009,202(1):41-53
Bryophytes and lichens abound in many arctic ecosystems and can contribute substantially to the ecosystem net primary production
(NPP). Because of their growth seasonality and their potential for growth out of the growing season peak, bryophyte and lichen
contribution to NPP may be particularly significant when vascular plants are less active and ecosystems act as a source of
carbon (C). To clarify these dynamics, nonvascular and vascular aboveground NPP was compared for a subarctic heath during
two contrasting periods of the growing season, viz. early-mid summer and late summer-early autumn. Nonvascular NPP was determined
by assessing shoot biomass increment of three moss species (Hylocomium splendens, Pleurozium schreberi and Dicranum elongatum) and by scaling to ecosystem level using average standing crop. For D. elongatum, these estimates were compared with production estimates obtained from measurements of shoot length increase. Vascular NPP
was determined by harvesting shrub and herb apical growth and considering production due to stem secondary growth of shrubs.
Hylocomium splendens and Pleurozium schreberi showed highest biomass growth in late summer, whereas for D. elongatum this occurred in early summer. Maximum relative growth rates were ca. 0.003–0.007 g g−1 d−1. For D. elongatum, production estimates from length growth differed from estimations from biomass growth, likely because of an uncoupling between
length growth and biomass shoot growth. Nonvascular NPP was 0.37 and 0.46 g dry weight m−2 d−1, in early and late summer, respectively, whereas in the same periods vascular NPP was 3.6 and 1.1 g dry weight m−2 d−1. The contribution of nonvascular NPP to total aboveground NPP was therefore minor in early summer but substantial in late
summer, when 25% of the C accumulated by the vegetation was incorporated into nonvascular plant tissue. The expected global
change-induced reduction of nonvascular plant biomass in subarctic heath is likely therefore to enhance C release during the
late part of the growing season. 相似文献
16.
Primary production rates, chlorophyll and phytoplankton biovolume were measured monthly from April 2003 to November 2004 in
Lake Tana, a large tropical lake in the highlands of Ethiopia. The lake is characterised by low nutrient concentrations, and
a low water transparency due to high silt load of the inflowing rivers during the rainy seasons (May–November) and daily resuspension
of sediments in the inshore zone. The mean chlorophyll-a concentrations varied seasonally and ranged from 2.6 mg m−3 to 8.5 mg m−3 (mean: 4.5 mg m−3) in the offshore zone. Primary production was measured using the light–dark bottles technique. We incubated only at three
depths, i.e. 0.6, 1.2 and 1.8 m. Therefore, we may have missed a substantial part of the depth production profile and probably
also frequently missed P
max. Gross primary production in the openwater averaged 2.43 g O2 m−2 d−1 and ranged between 0.03 g O2 m−2 d−1 and 10.2 g O2 m−2 d−1; production was significantly higher in the inshore zone. The highest production rates were observed in the post-rainy season
(Oct–Nov), which coincided with a bloom of Microcystis and higher chlorophyll levels. This seasonal high production is probably caused by a relatively high nutrient availability
in combination with favourable light conditions. The gross primary production rates of L. Tana are among the lowest compared
with other tropical lakes. This will be partly the result of our underestimation of gross primary production by often missing
P
max. Another cause is the oligotrophic nature of the lake in combination with its relatively low water transparency. The gross
primary production per unit chlorophyll in the openwater zone was in the same range as in 30 other tropical lakes and reservoirs.
The higher primary production in the inshore zone is probably the result of the daily water column mixing (Z
mix ≥ Z
t) in this area, enhancing nutrient recycling. A large proportion of the annual primary production is realised in one of the
four seasons only. This productive post-rainy season is relatively short (2 months) and therefore efficiency of transfer of
matter between the first and second trophic level of the Lake ecosystem will be poor. 相似文献
17.
The morphological, anatomical and physiological variations of leaf traits were analysed during Quercus ilex L. leaf expansion. The leaf water content (LWC), leaf area relative growth rate (RGRl) and leaf dry mass relative growth rate (RGRm) were the highest (76±2 %, 0.413 cm2 cm−2 d−1, 0.709 mg mg−1 d−1, respectively) at the beginning of the leaf expansion process (7 days after bud break). Leaf expansion lasted 84±2 days when
air temperature ranged from 13.3±0.8 to 27.6±0.9 °C. The net photosynthetic rate (P
N), stomatal conductance (g
s), and chlorophyll content per fresh mass (Chl) increased during leaf expansion, having the highest values [12.62±1.64 μmol
(CO2) m−2 s−1, 0.090 mol (H2O) m−2 s−1, and 1.03±0.08 mg g−1, respectively] 56 days after bud break. Chl was directly correlated with leaf dry mass (DM) and P
N. The thickness of palisade parenchyma contributed to the total leaf thickness (263.1±1.5 μm) by 47 %, spongy layer thickness
38 %, adaxial epidermis and cuticle thickness 9 %, and abaxial epidermis and cuticle thickness 6 %. Variation in leaf size
during leaf expansion might be attributed to a combination of cells density and length, and it is confirmed by the significant
(p<0.001) correlations among these traits. Q. ilex leaves reached 90 % of their definitive structure before the most severe drought period (beginning of June — end of August).
The high leaf mass area (LMA, 15.1±0.6 mg cm−2) at full leaf expansion was indicative of compact leaves (2028±100 cells mm−2). Air temperature increasing might shorten the favourable period for leaf expansion, thus changing the final amount of biomass
per unit leaf area of Q. ilex. 相似文献
18.
James E. Kaldy 《Hydrobiologia》2006,560(1):433-217
The non-indigenous seagrass Zostera japonica Ascher. & Graeb. (dwarf eelgrass) was first identified in central Oregon (USA) estuaries about 30 years ago. The autecology
of this species is poorly described at the southern end of its non-native range although several process oriented studies
have been conducted. I examined the production ecology of Z. japonica in the Yaquina Bay estuary. Strong seasonal patterns in light and temperature appeared to control the seasonal variations
in biomass and growth. Above- and below-ground biomass ranged between 40–100 and 70–170 gdw m−2 respectively and seasonal changes in the root:shoot ratio were controlled by above-ground biomass dynamics. Shoot density
ranged between 4000 and 11 000 shts m−2. Areal leaf growth ranged between 0.1 and 1.7 gdw m−2 d−1 and annual production was about 314 ± 60 gdw m−2 y−1 (mean ± SD). Nutrients were not limiting in this system as a result of coastal upwelling and watershed inputs. The Z. japonica population studied in Oregon exhibited different patterns of persistence, phenology and flowering intensity relative to other
populations along its native and non-native range. These differences suggest that management policies developed for one site
may not be appropriate for other sites. The data presented here greatly expands our knowledge base on Z. japonica and provides insight to the processes controlling the dynamics and spread of this non-indigenous seagrass.
An erratum to this article is available at . 相似文献
19.
A microprocessor controlled apparatus is described which can measure, control and record nitrate uptake byLolium perenne in nutrient solution, comparing seven selection lines in duplicate. Nutrient solution flowed at 1 min−1, and linear response was found from 10−1 to 10−4
M NO
3
−
.
Uptake rates for Lolium were between 10−5 and 10−4
M NO
3
−
, plant−1, h−1, which agreed with previous, manually determined, rates, ‘Overshoot’ in nitrate dosing, which was a problem with manual systems,
was eliminated. Nitrate concentration was controlled (±3%) in modified Hoagland’s solution. 相似文献
20.
The influence of toluene concentration on the specific growth rate, cellular yield, specific CO2, and metabolite production by Pseudomonas putida F1 (PpF1) was investigated. Both cellular yield and specific CO2 production remained constant at 1.0 ± 0.1 g biomass dry weight (DW) g−1 toluene and 1.91 ± 0.31 g CO2 g−1 biomass, respectively, under the tested range of concentrations (2–250 mg toluene l−1). The specific growth rate increased up to 70 mg toluene l−1. Further increases in toluene concentration inhibited PpF1 growth, although inhibitory concentrations were far from the application range of biological treatment processes. The specific
ATP content increased with toluene concentration up to toluene concentrations of 170 mg l−1. 3-Methyl catechol (3-MC) was never detected in the cultivation medium despite being an intermediary in the TOD pathway.
This suggested that the transformation from toluene to 3-MC was the limiting step in the biodegradation process. On the other
hand, benzyl alcohol (BA) was produced from toluene in a side chain reaction. This is, to the best of our knowledge, the first
reported case of methyl monoxygenation of toluene by PpF1 not harboring the pWW0 TOL plasmid. In addition, the influence of 3-MC, BA, and o-cresol on toluene degradation was investigated respirometrically, showing that toluene-associated respiration was not significantly
inhibited in the presence of 10–100 mg l−1 of the above-mentioned compounds. 相似文献