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1.
Ecosystem properties and microbial community changes in primary succession on a glacier forefront 总被引:13,自引:0,他引:13
We studied microbial community composition in a primary successional chronosequence on the forefront of Lyman Glacier, Washington,
United States. We sampled microbial communities in soil from nonvegetated areas and under the canopies of mycorrhizal and
nonmycorrhizal plants from 20- to 80-year-old zones along the successional gradient. Three independent measures of microbial
biomass were used: substrate-induced respiration (SIR), phospholipid fatty acid (PLFA) analysis, and direct microscopic counts.
All methods indicated that biomass increased over successional time in the nonvegetated soil. PLFA analysis indicated that
the microbial biomass was greater under the plant canopies than in the nonvegetated soils; the microbial community composition
was clearly different between these two types of soils. Over the successional gradient, the microbial community shifted from
bacterial-dominated to fungal-dominated. Microbial respiration increased while specific activity (respiration per unit biomass)
decreased in nonvegetated soils over the successional gradient. We proposed and evaluated new parameters for estimating the
C use efficiency of the soil microbial community: “Max” indicates the maximal respiration rate and “Acc” the total C released
from the sample after a standard amount of substrate is added. These, as well as the corresponding specific activities (calculated
as Max and Acc per unit biomass), decreased sharply over the successional gradient. Our study suggests that during the early
stages of succession the microbial community cannot incorporate all the added substrate into its biomass, but rapidly increases
its respiration. The later-stage microbial community cannot reach as high a rate of respiration per unit biomass but remains
in an “energy-saving state,” accumulating C to its biomass.
Received: 4 June 1998 / Accepted: 11 January 1999 相似文献
2.
Konopka A Zakharova T Nakatsu C 《Journal of industrial microbiology & biotechnology》2002,29(5):286-291
The kinetics of substrate degradation and bacterial growth was determined in a microbial community from a biomass recycle
reactor that had been deprived of substrate feed for 0–32 days. Starvation caused changes in bacterial numbers, community
composition, and physiological state. Substrate starvation for less than 1 day resulted in modest (less than threefold) changes
in endogenous respiration rate, ATP content, and biomass level. During a starvation period of 32 days, there were substantial
changes in microbial community composition, as assessed by denaturing gradient gel electrophoresis (DGGE) fingerprinting of
PCR amplicons of a portion of the 16S rDNA or by phospholipid fatty acid (PLFA) analysis. When the starved communities were stimulated with organic nutrients,
the growth kinetics was a function of the length of the starvation period. For starvation periods of 2–8 days prior to nutrient
addition, there was a phase of suboptimal exponential growth (S-phase) in which the exponential growth rate was about 30%
of the ultimate unrestricted growth rate. S-phase lasted for 2–8 h and then unrestricted growth occurred at rates of 0.3–0.4
h−1. At starvation times of 12 and 20 days, a lag phase preceded S-phase and the unrestricted growth phase.
Received 04 January 2002/ Accepted in revised form 08 August 2002 相似文献
3.
Pollutant degradation in biotrickling filters for waste air treatment is generally thought to occur only in the biofilm.
In two experiments with toluene degrading biotrickling filters, we show that suspended microorganisms in the recycle liquid
may substantially contribute to the overall pollutant removal. Two days after reactor start up, the overall toluene elimination
capacity reached a maximum of 125 g m−3 h−1, which was twice that found during prolonged operation. High biodegradation activity in the recycle liquid fully accounted
for this short-term peak of pollutant elimination. During steady-state operation, the toluene degradation in the recycle liquid
was 21% of the overall elimination capacity, although the amount of suspended biomass was only 1% of the amount of immobilized
biomass. The results suggest that biotrickling filter performance may be improved by selecting operating conditions allowing
for the development of an actively growing suspended culture.
Received: 16 June 1999 / Received revision: 17 November 1999 / Accepted: 15 December 1999 相似文献
4.
A Konopka T Zakharova L Oliver E Paseuth R F Turco 《Journal of industrial microbiology & biotechnology》1998,20(3-4):232-237
The transition in physiological state was investigated between a carbon-limited chemostat population and microbes growing
very slowly in a biomass recycle reactor. The mixed microbial population was metabolizing a mixture of biopolymers and linear
alkylbenzene sulfonate, formulated to represent the organic load in graywater. Biomass increased 30-fold during the first
14 days after a shift from chemostat to biomass recycle mode. The ratios of ATP and RNA to cell protein decreased over the
first days but then remained constant. The specific rate of CO2 production by microbes in the reactor decreased 6-fold within 24 h after the shift, and respiratory potentials declined 2–3
fold during the first 7 days. Whereas chemostat cultures used equal proportions of organic carbon substrate for catabolism
and anabolism, the proportion of organic substrate oxidized to CO2 rose from 62 to 82% over the first 8 days in a biomass recycle reactor, and eventually reached 100% as this reactor population
exhibited no net growth. Biomass recycle populations removed from the system and subjected to a nutritional shift-up did not
immediately initiate exponential growth. The physiological state of cells in the biomass recycle reactor may be distinct from
those grown in batch or continuous culture, or from starved cells.
Received 02 June 1997/ Accepted in revised form 20 February 1998 相似文献
5.
We studied the role of nematode predation in the functioning of detrital food webs assembled in microcosms. The microcosms
contained defaunated humus and litter materials, a diverse microbial community with bacteria, fungi and protozoa, and a birch
(Betula pendula) seedling infected with mycorrhizal fungi. Different levels of top-down control upon microbivorous nematodes were set up
by assembling food webs either without predators, or in combinations with a specialist and a non-specialist predatory mite
(Mesostigmata). The nematode community was composed of either (1) three species of bacterivorous, or (2) three species of
fungivorous nematodes or (3) both groups together. After two growing periods for the birch (38 weeks), the microcosms were
destructively sampled for animal and microbial biomasses, concentration of mineral N in the soil, plant biomass and plant
N concentration. The specialist predator reduced biomasses of both bacterial- and fungal-feeding nematodes by more than 50%,
whereas the non-specialist predator weakly increased the biomass of fungivorous nematodes. Thus, under high predation pressure,
the biomass of microbivores changed as predicted by trophic dynamic models assuming strong top-down control and uniformly
behaving trophic levels. Despite this, microbial biomass was unaffected by the predators. However, microbial respiration increased
slightly in the presence of predators. Assuming that microbial respiration correlates with microbial productivity, the increase
in microbial respiration indicates a cascading productivity regulation. The composition of the microbivore community had only
a minor effect on the outcome of the top-down control on microbes. The >50% reduction in nematode biomass and respiration
coincided with <16% increase in microbial respiration and did not affect microbial biomass. Presence of the specialist predator
slightly reduced soil NH+
4 concentration in communities with fungivore nematodes but plant growth and N uptake remained unchanged. Thus, the structure
of the community only weakly controlled nutrient mineralisation.
Received: 18 May 1998 / Accepted: 3 May 1999 相似文献
6.
Nitrifying granules cultivation in a sequencing batch reactor at a low organics-to-total nitrogen ratio in wastewater 总被引:4,自引:0,他引:4
It is possible to cultivate aerobic granular sludge at a low organic loading rate and organics-to-total nitrogen (COD/N) ratio
in wastewater in the reactor with typical geometry (height/diameter = 2.1, superficial air velocity = 6 mm/s). The noted nitrification
efficiency was very high (99%). At the highest applied ammonia load (0.3 ± 0.002 mg NH4+–N g total suspended solids (TSS)−1 day−1, COD/N = 1), the dominating oxidized form of nitrogen was nitrite. Despite a constant aeration in the reactor, denitrification
occurred in the structure of granules. Applied molecular techniques allowed the changes in the ammonia-oxidizing bacteria
(AOB) community in granular sludge to be tracked. The major factor influencing AOB number and species composition was ammonia
load. At the ammonia load of 0.3 ± 0.002 mg NH4+–N g TSS−1 day−1, a highly diverse AOB community covering bacteria belonging to both the Nitrosospira and Nitrosomonas genera accounted for ca. 40% of the total bacteria in the biomass. 相似文献
7.
The fermentation characteristics of the novel, thermotolerant, isolate Kluyveromyces marxianus var marxianus were determined to evaluate its aptitude for use in an ethanol production process. Sustainable growth was not observed under
anaerobic conditions, even in the presence of unsaturated fatty acid and sterol. A maximum ethanol concentration of 40 g L−1 was produced at 45°C, with an initial specific ethanol production rate of 1.7 g g−1 h−1. This was observed at ethanol concentrations below 8 g L−1 and under oxygen-limited conditions. The low ethanol tolerance and low growth under oxygen-limited conditions required for
ethanol production implied that a simple continuous process was not feasible with this yeast strain. Improved productivity
was achieved through recycling biomass into the fermenter, indicating that utilising an effective cell retention method such
as cell recycle or immobilisation, could lead to the development of a viable industrial process using this novel yeast strain.
Received 14 February 1998/ Accepted in revised form 19 May 1998 相似文献
8.
Nalina Nadarajah D. Grant Allen Roberta R. Fulthorpe 《Applied microbiology and biotechnology》2010,88(5):1205-1214
Problems with deflocculation and solids separation in biological wastewater treatment systems are linked to fluctuations in
physicochemical conditions. This study examined the composition of activated sludge bacterial communities in lab-scale sequencing
batch reactors treating bleached kraft mill effluent, under transient temperature conditions (30 to 45 °C) and their correlation
to sludge settleability problems. The bacterial community composition of settled and planktonic biomass samples in the reactors
was monitored via denaturing gradient gel electrophoresis of 16S ribosomal RNA gene fragments. Our analysis showed that settled
biomass has a different community composition from the planktonic biomass (49 ± 7% difference based on Jaccard similarity
coefficients; p < 0.01). During times of poor sludge compression, the settled and planktonic biomass became more similar. This observation
supports the hypothesis that settling problems observed were due to deflocculation of normally settling flocs rather than
the outgrowth of non-settling bacterial species. 相似文献
9.
E. Kostyál M. Borsányi L. Rigottier-Gois M. S. Salkinoja-Salonen 《Applied microbiology and biotechnology》1998,50(5):612-622
The dechlorinating and genotoxicity-removing activities of nitrifying fluidized-bed reactor biomass towards chlorinated organic
compounds in water were shown at level below 1 ppm. The removal rates of adsorbable organic halogens were 200 μg Cl (g VS
day)−1 for chlorinated humic ground water and 50 μyg Cl (g VS day)−1 for chlorinated lake water when studied in batch mode. In a sequenced batch mode the removal rates μg Cl (g VS day)−1] were 2000 from chlorohumus, 1400–1800 from chlorophenols in chlorinated ground water, and 430–720 from chlorohumus in chlorinated
lake water. Genotoxicity was removed to a large extent (60%–80%) from the chlorinated waters upon incubation with nitrifying
reactor biomass. 2,6-Di-, 2,4,6-tri and 2,3,4,6-tetrachlorophenols competed with chlorinated water organohalogens for dechlorination.
The dechlorination of chlorophenols and chlorohumus required no ammonia and was not prevented by inhibitors of ammonia oxidation,
nitrapyrin, parathion, sodium diethyldithiocarbamate, or allylthiourea. Electron microscopical inspection of the biomass showed
the dominance of clusters of bacteria resembling known nitrifying species, Nitrosomonas, Nitrobacter, and Nitrosospira. This was supported by polymerase chain reaction amplification of the biomass DNA with four different primers, revealing
the presence of 16S rDNA sequences assignable to the same species. The most intensive band obtained with the Nitroso4E primer
was shown to be closely related to Nitrosomonas europaea by restriction analysis.
Received: 27 March 1998 / Received revision: 30 July 1998 / Accepted: 31 July 1998 相似文献
10.
Biomass and metabolism of zooplankton in the Bransfield Strait (Antarctic Peninsula) during austral spring 总被引:1,自引:1,他引:0
Zooplankton biomass (as dry weight), respiration and ammonia excretion were studied in three different size classes (200–500,
500–1000 and >1000 μm) in the Bransfield Strait during December 1991. Average mesozooplankton biomass was 86.45 ± 56.74 mg · dry weight · m−2, which is in the lower range of the values cited in the literature for polar waters. Higher biomass was observed in the Weddell
water. The small size fraction accounted for about 50% of total biomass while the largest one represented 35%. Rather high
metabolic rates were found, irrespective of whether the organisms were incubated in the presence of food. No significant differences
were observed in mass specific respiration and ammonia excretion rates between different temperatures of incubation (0.2–2.3°C)
and between the size classes studied. Because of the very low biomass values observed, the metabolic requirements of mesozooplankton
during December represented a small fraction of the primary production.
Accepted: 5 September 1998 相似文献
11.
Non-toluene-associated respiration (NTAR) within a Pseudomonas putida 54G biofilm growing on toluene as sole external carbon source was evaluated using oxygen microelectrodes in a flat-plate
vapor-phase biological reactor. Two fluorescent probes, 2,4-diamidino-2-phenylindole and 5-cyano-2,3-ditolyltetrazolium chloride,
were used to evaluate the number of total and respiring cells respectively within the biofilm. Biofilm samples were also analyzed
for viable and toluene-culturable cells by spread-plating on non-selective and selective media respectively. Fractions of
viable stressed, respiring and non-respiring cells within the biofilm were evaluated. The NTAR rate was positively correlated
with the fraction of viable stressed and non-respiring cells within the biofilm, which suggested the capability of some cells
to grow at the expense of leakage and lysis products coming from injured and dead cells. This effect was more pronounced at
higher toluene concentration. Results suggest that NTAR should be incorporated into mathematical models of biofilm reactors
degrading volatile organic carbon compounds.
Received: 4 January 1997 / Received revision: 20 March 1997 / Accepted: 27 March 1997 相似文献
12.
The sequencing batch reactor as a powerful tool for the study of slowly growing anaerobic ammonium-oxidizing microorganisms 总被引:145,自引:0,他引:145
M. Strous J. J. Heijnen J. G. Kuenen M. S. M. Jetten 《Applied microbiology and biotechnology》1998,50(5):589-596
Currently available microbiological techniques are not designed to deal with very slowly growing microorganisms. The enrichment
and study of such organisms demands a novel experimental approach. In the present investigation, the sequencing batch reactor
(SBR) was applied and optimized for the enrichment and quantitative study of a very slowly growing microbial community which
oxidizes ammonium anaerobically. The SBR was shown to be a powerful experimental set-up with the following strong points:
(1) efficient biomass retention, (2) a homogeneous distribution of substrates, products and biomass aggregates over the reactor,
(3) reliable operation for more than 1 year, and (4) stable conditions under substrate-limiting conditions. Together, these
points made possible for the first time the determination of several important physiological parameters such as the biomass
yield (0.066 ± 0.01 C-mol/mol ammonium), the maximum specific ammonium consumption rate (45 ± 5 nmol/mg protein/min) and the
maximum specific growth rate (0.0027 · h−1, doubling time 11 days). In addition, the persisting stable and strongly selective conditions of the SBR led to a high degree
of enrichment (74% of the desired microorganism). This study has demonstrated that the SBR is a powerful tool compared to
other techniques used in the past. We suggest that the SBR could be used for the enrichment and quantitative study of a large
number of slowly growing microorganisms that are currently out of reach for microbiological research.
Received: 14 May 1998 / Received last revision: 30 July 1998 / Accepted: 31 July 1998 相似文献
13.
A. De Smul J. Dries L. Goethals H. Grootaerd W. Verstraete 《Applied microbiology and biotechnology》1997,48(3):297-303
In a mesophilic (30–35 °C), sulphidogenic, ethanol-fed expanded-granular-sludge-blanket reactor, sulphate, at loading rates
of up to 10.0–12.0 g Sl−1␣day−1, was removed with an average efficiency of more than 80%. The pH was between 7.7 and 8.3 and the maximal total dissolved
sulphide concentration was up to 20 mM S (650 mg S/l). The alkaline pH was maintained by either a pH-control unit with sodium
hydroxide or by stripping part of the sulphide and CO2 from the recycle with nitrogen gas. The superficial upstream liquid velocity (v
up) was 3.0–4.5 m/h. The ratio of ethanol to sulphur was near stoichiometry. At alkaline pH, the activity of the acetotrophic
sulphate-reducing bacteria, growing on acetate, was strongly enhanced, whereas at pH below 7.7 the acetotrophic sulphate-reducing
bacteria were inhibited by aqueous H2S. With regard to the removal efficiency and operational stability, external stripping with N2 and pH control were equally successful.
Received: 2 December 1996 / Received revision: 13 March 1997 / Accepted: 15 March 1997 相似文献
14.
Phosphate Addition and Plant Species Alters Microbial Community Structure in Acidic Upland Grassland Soil 总被引:2,自引:0,他引:2
Agricultural improvement (addition of fertilizers, liming) of seminatural acidic grasslands across Ireland and the UK has
resulted in significant shifts in floristic composition, soil chemistry, and microbial community structure. Although several
factors have been proposed as responsible for driving shifts in microbial communities, the exact causes of such changes are
not well defined. Phosphate was added to grassland microcosms to investigate the effect on fungal and bacterial communities.
Plant species typical of unimproved grasslands (Agrostis capillaris, Festuca ovina) and agriculturally improved grasslands (Lolium perenne) were grown, and phosphate was added 25 days after seed germination, with harvesting after a further 50 days. Phosphate addition
significantly increased root biomass (p < 0.001) and shoot biomass (p < 0.05), soil pH (by 0.1 U), and microbial activity (by 5.33 mg triphenylformazan [TPF] g−1 soil; p < 0.001). A slight decrease (by 0.257 mg biomass-C g−1 soil; p < 0.05) in microbial biomass after phosphate addition was found. The presence of plant species significantly decreased soil
pH (p < 0.05; by up to 0.2 U) and increased microbial activity (by up to 6.02 mg TPF g−1 soil) but had no significant effect on microbial biomass. Microbial communities were profiled using automated ribosomal intergenic
spacer analysis. Multidimensional scaling plots and canonical correspondence analysis revealed that phosphate addition and
its interactions with upland grassland plant species resulted in considerable changes in the fungal and bacterial communities
of upland soil. The fungal community structure was significantly affected by both phosphate (R = 0.948) and plant species (R = 0.857), and the bacterial community structure was also significantly affected by phosphate (R = 0.758) and plant species (R = 0.753). Differences in microbial community structure following P addition were also revealed by similarity percentage analysis.
These data suggest that phosphate application may be an important contributor to microbial community structural change during
agricultural management of upland grasslands. 相似文献
15.
Stem respiration of ponderosa pines grown in contrasting climates: implications for global climate change 总被引:7,自引:0,他引:7
We examined the effects of climate and allocation patterns on stem respiration in ponderosa pine (Pinus ponderosa) growing on identical substrate in the cool, moist Sierra Nevada mountains and the warm, dry, Great Basin Desert. These environments
are representative of current climatic conditions and those predicted to accompany a doubling of atmospheric CO2, respectively, throughout the range of many western north American conifers. A previous study found that trees growing in
the desert allocate proportionally more biomass to sapwood and less to leaf area than montane trees. We tested the hypothesis
that respiration rates of sapwood are lower in desert trees than in montane trees due to reduced stem maintenance respiration
(physiological acclimation) or reduced construction cost of stem tissue (structural acclimation). Maintenance respiration
per unit sapwood volume at 15°C did not differ between populations (desert: 6.39 ± 1.14 SE μmol m−3 s−1, montane: 6.54 ± 1.13 SE μmol m−3 s−1, P = 0.71) and declined with increasing stem diameter (P = 0.001). The temperature coefficient of respiration (Q
10) varied seasonally within both environments (P = 0.05). Construction cost of stem sapwood was the same in both environments (desert: 1.46 ± 0.009 SE g glucose g−1 sapwood, montane: 1.48 ± 0.009 SE glucose g−1 sapwood, P = 0.14). Annual construction respiration calculated from construction cost, percent carbon and relative growth rate was greater
in montane populations due to higher growth rates. These data provide no evidence of respiratory acclimation by desert trees.
Estimated yearly stem maintenance respiration was greater in large desert trees than in large montane trees because of higher
temperatures in the desert and because of increased allocation of biomass to sapwood. By analogy, these data suggest that
under predicted increases in temperature and aridity, potential increases in aboveground carbon gain due to enhanced photosynthetic
rates may be partially offset by increases in maintenance respiration in large trees growing in CO2-enriched atmospheres.
Received: 4 November 1996 / Accepted: 23 January 1997 相似文献
16.
The ability of a photobioreactor to fix CO2 was evaluated with the thermophilic cyanobacterium, Synechocystis aquatilis SI-2. The reactor consisted of three to five flat plates of transparent acrylic plastic standing upright and in parallel
and giving a 0.015-m light path. The reactor was 0.8 m high and 1 m long with 9 l working volume. The effects of the orientation
of the vertical bioreactor, distance between the plates, and culture temperature on the productivity of biomass were investigated
during the summer of 1998 in Kamaishi (39°N, 142°E), Japan. When the illuminated surface reactor was placed in an east–west-facing
orientation, the biomass productivity was roughly 1.4-fold higher than that obtained in a north–south-facing orientation,
because the former received more solar energy than the latter. The productivity based on the overall land area was the same
for plates set either 0.25 m or 0.5 m apart. However, the volumetric productivity of the reactor in which the plates were
set 0.25 m apart was lower than that when the plates were set 0.5 m apart, since the former plates received relatively lower
solar irradiation because of severe mutual shading. When the culture temperature was maintained in its optimal range (37–43 °C),
the productivity was 50% greater than that obtained in a culture at ambient temperature (20–44 °C). The biomass productivity
and CO2 fixation rate were investigated under various experimental conditions. The maximum rate of 53 g CO2 m−2 day−1 was achieved in the temperature-regulated culture with the reactor set in an east–west-facing orientation, the distance between
plates being 0.25 m.
Received: 6 may 1999 / Received revision: 14 June 1999 / Accepted 5 July 1999 相似文献
17.
A reaction chamber was developed to determine the respiratory activity of microorganisms immobilized on various support materials
for waste gas treatment. The volumetric respiration rate was identified as a suitable parameter for estimating the degradative
activity of waste gas treatment plants. A laboratory trickle-bed reactor was filled with either granular clay, polyamide beads,
or sintered styrofoam. n-Butanol was used as model solvent to determine the efficiency of its elimination from the gas phase. This crucial parameter
was correlated with the volumetric degradation rate, determined from the overall material balance under steady-state operating
conditions. The volumetric respiration rate of n-butanol was determined with the reaction chamber, and exceeded the volumetric degradation rate of n-butanol determined from the reactor 16- to 26-fold, depending on the support material. The respiration rate was correlated
to the degradation rate by the stoichiometry of n-butanol oxidation and a correlation factor of 2.6–4.3. The volumetric respiration rate appeared to be a suitable parameter
to determine the degradative activity of the trickle-bed reactor used. The volumetric respiration rate can be ultimately applied
to estimate the efficiency of elimination of an organic pollutant and to calculate the dimensions of a reactor required to
eliminate a given organic load from waste gas.
Received: 20 February 1997 / Received revision: 20 May 1997 / Accepted: 20 May 1997 相似文献
18.
Lolium temulentum L. Ba 3081 was grown hydroponically in air (350 μmol mol−1 CO2) and elevated CO2 (700 μmol mol−1 CO2) at two irradiances (150 and 500 μmol m−2 s−1) for 35 days at which point the plants were harvested. Elevated CO2 did not modify relative growth rate or biomass at either irradiance. Foliar carbon-to-nitrogen ratios were decreased at elevated
CO2 and plants had a greater number of shorter tillers, particularly at the lower growth irradiance. Both light-limited and light-saturated
rates of photosynthesis were stimulated. The amount of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) protein was
increased at elevated CO2, but maximum extractable Rubisco activities were not significantly increased. A pronounced decrease in the Rubisco activation
state was found with CO2 enrichment, particularly at the higher growth irradiance. Elevated-CO2-induced changes in leaf carbohydrate composition were small in comparison to those caused by changes in irradiance. No CO2-dependent effects on fructan biosynthesis were observed. Leaf respiration rates were increased by 68% in plants grown with
CO2 enrichment and low light. We conclude that high CO2 will only result in increased biomass if total light input favourably increases the photosynthesis-to-respiration ratio.
At low irradiances, biomass is more limited by increased rates of respiration than by CO2-induced enhancement of photosynthesis.
Received: 23 February 1999 / Accepted: 15 June 1999 相似文献
19.
A Konopka T Zakharova L Oliver R F Turco 《Journal of industrial microbiology & biotechnology》1997,18(4):235-240
In a continuous flow bioreactor seeded with microbes from municipal activated sludge, complete organic carbon oxidation of
simulated graywater (wastewater produced in human residences, excluding toilet wastes) was achieved at dilution rates up
to 0.36 h−1 in the presence of 64.1 μ M linear alkylbenzenesulfonate (LAS) L−1. At LAS concentrations of 187 μ M, the system functioned only at dilution rates up to 0.23 h−1, and the biomass yield was two-fold lower. There were physiological changes in the microbial communities under different
operating conditions, as measured by specific contents of ATP and extracellular hydrolases as well as the respiratory potential
of the biomass. LAS inhibited the activity of LAS-degrading microbes at >150 μ M LAS, and the activity of other microbes at >75 μ M LAS. Chemical analysis of graywater indicated that samples consisted primarily of biological polymers (proteins and polysaccharides)
and lower concentrations of surfactants. Biological remediation of graywater is possible, although treatment efficiency is
influenced by the operating conditions and wastestream composition.
Received 08 July 1996/ Accepted in revised form 14 November 1996 相似文献
20.
Semeneh Mengesha Frank Dehairs Michel Fiala Marc Elskens Leo Goeyens 《Polar Biology》1998,20(4):259-272
This study investigates the dynamics of phytoplankton communities and nitrogen uptake in the Indian sector of the Southern
Ocean during spring and summer. The study area is oligotrophic (Chl a stocks <50 mg m−2); nevertheless, a large spatial variation of phytoplankton biomass and community structure was observed. During both seasons
the phytoplankton community in the seasonal ice zone showed higher biomasses and was mainly composed of large diatom cells.
However, in the permanently open ocean zone the community had low biomass and was chiefly composed of nano- and picoflagellates.
In the polar front zone, although biomass was higher, the community structure was similar to the open ocean zone. The results
suggest that the variation in phytoplankton community structure on a larger scale resonates with gradients in water column
stability and nutrient distribution. However, significant changes in biomass and nutrient stocks but little change in community
structure were observed. Absolute nitrogen uptake rates were generally low, but their seasonal variations were highly significant.
During spring the communities displayed high specific nitrate uptake (mean rate = 0.0048 h−1), and diatoms (in the seasonal ice zone) as well as nano- and picoflagellates (in the permanently open ocean zone and polar
front zone) were mainly based on new production (mean ƒ-ratio = 0.69). The transition to summer was accompanied by a significant
reduction in nitrate uptake rate (0.0048 h−1 → 0.0011 h−1) and a shift from predominantly new to regenerated production (ƒ-ratio 0.69 → 0.39). Ammonium played a major role in the
seasonal dynamics of phytoplankton nutrition. The results emphasize that, despite a large contrast in community structure,
the seasonal dynamics of the nitrogen uptake regime and phytoplankton community structure in all three subsystems were similar.
Additionally, this study supports our previous conclusion that the seasonal shift in nitrogen uptake regime can occur with,
as well as without, marked changes in community structure.
Received: 2 December 1997 / Accepted: 20 April 1998 相似文献