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1.
Production rates, abundance, chlorophyll a (Chl a) concentrations and pigment composition were measured for three size classes (<2 μm, 2–11 μm and >11 μm) of phytoplankton
from May to December 2000 in deep, mesotrophic, alpine lake Mondsee in Austria. The study focuses on differences among phytoplankton
size fractions characterised by their surface area to volume ratio ([mm2 l−1: mm3l−1]), pigment distribution patterns and photosynthetic rates. Particular attention was paid to autotrophic picophytoplankton
(APP, fraction <2 μm) since this size fraction differed significantly from the two larger size fractions. Among the three
fractions, APP showed the highest surface area to volume ratios and a high persistence in the pattern of lipophilic pigments
between temporarily and spatially successive samples (about 80% similarity of pigment composition between samples over seasons
and depths). The epilimnetic abundance of APP varied seasonally with an annual maximum of 180 × 103 cells ml−1 in June (at 4–9 m). The minimum (October at 12 m) was more than an order of magnitude lower (4.9 × 103 ml−1). APP peaked during autumn and contributed between 24% and 42% to the total area-integrated Chl a (10–23 mg m−2) and between 16% and 58% to total area-integrated production (5–64 mg m−2 h−1) throughout seasons. 相似文献
2.
Biomanipulation of Lago di Candia (Northern Italy): a three-year experience of aquatic macrophyte management 总被引:1,自引:1,他引:0
A long-term experimental aquatic plant management programme has been in progress since 1985 in the eutrophic Lago di Candia
(Northern Italy). 7.7 ha of water chestnut (Trapa natans L.) were harvested in 1986, 8.2 ha in 1987 and 11.0 ha in 1988, from August to October, removing 334, 290 and 418 tons of
fresh plant material, respectively, from the lake. This annual harvesting of about 50% of the total water chestnut cover resulted
in the removal from the lake of about 70 kg yr−1 of phosphorus, a significant portion of the external annual loading originating mainly from run-off and precipitation. In
addition, up to 38t yr−1 of organic matter and 1t yr−1 of nitrogen were removed. First results of the effect of the harvesting on Secchi-disc transparency, oxygen, total phosphorus,
phytoplankton and zooplankton are discussed also in connection with a study of fish manipulation (Giussaniet al., 1990). 相似文献
3.
The influence of substrate, light intensity, temperature and growth phase on the dry weight per unit biovolume of both living
Phormidium autumnale trichomes and living single cells was investigated microinterferometrically. With a Mach–Zehnder Interference Microscope,
both the interference-stripe-field method and the phase-shift method were used to measure the optical path differences (OPD)
of cells and trichomes. To calculate the cellular dry weight of trichomes, the trichome diameters have to be measured. Widths
between 4 and 7 μm were determined. Thick trichomes are characteristic for growth on agar-solidified medium, whereas this
was observed in single cases only from trichomes growing on soil surfaces. A reliable prediction of trichome width from growth
conditions is not possible. The dry weights per unit biovolume (fg μm−3) are independent of the studied parameters during the exponential growth phase (296 ± 22 fg μm−3) with exception of the agar-based cultures growing at low light intensity (259 ± 16 fg μm−3). During the stationary phase, dry weights per unit biovolume increase independently of growth conditions (353 ± 39 fg μm−3). Two separate factors of 0.14 and 0.17 for converting biovolume (mm3) of cells to milligrams carbon could be determined by comparing the growth phase and stationary phase-dependent average values
of dry weights per unit biovolume, respectively. These conversion factors could be used as species-specific factors for Phormidium growing on soil surfaces. Irrespective of the method, both the stripe-field and phase-shift method gave similar results.
However, the phase-shift method measured lower variances of values. Additionally, detailed quantifying investigations of structures
within cells are possible. Thus, the phase-shift method could be a powerful analytical tool in, e.g., ecotoxicological monitoring
analyses. 相似文献
4.
Tissue culture and plant regeneration of blue grama grass, Bouteloua gracilis (H.B.K.) Lag. Ex Steud
Gerardo Armando Aguado-Santacruz José Luis Cabrera-Ponce Víctor Olalde-Portugal M. A. Rosario Sánchez-González Judith Márouez-Guzmán Luis Herrera-Estrella 《In vitro cellular & developmental biology. Plant》2001,37(2):182-189
Summary As a first step towards applying biotechnology to blue grama, Bouteloua gracilis (H. B. K.) Lag. ex Steud., we have developed a regenerable tissue culture system for this grass. Shoot apices were isolated
from 3-d-old seedlings and cultured in 15 different growth regulator formulations combining 2,4-dichlorophenoxyacetic acid
(2,4-D), Picloram (4-amino-3, 5,6-trichloropicolinic acid), N6-benzyladenine (BA) or adenine (6-aminopurine). The highest induction of organogenic callus was obtained with formulations
containing 1 mg l−1 (4.52 μM) 2,4-D plus 0.5 mg l−1 (2.22 μM) BA. and 2 mg l−1 (8.88 μM) BA plus 1 mg l−1 (4.14 μM) Picloram with or without 40 mg l−1 (296.08 μM) adenine. Lower frequencies of induction were obtained for embryogenic as compared to organogenic callus. The most efficient
treatments for induction of embryogenic callus contained 2 mg l−1 (9.05 μM) 2,4-D combined with 0.25 (1.11 μM) or 0.50 mg l−1 (2.22 μM) BA, or 1 mg l−1 (4.52 μM) 2,4-D with 0.50 mg l−1 (2.22 μM) BA. Regeneration was achieved in hormonefree Murashige anmd Skoog (MS) medium, half-strength MS medium or MS medium plus
1 mg l−1 (1.44 μM) gibberellic acid. The number of plantlets regenerated per 500 mg callus fresh weight on MS medium ranged from 9 for 2 mg
l−1 (9.05 μM) 2,4-D to 62.2 for induction medium containing 2 mg l−1 (8,28 μM) Picloram, 1 mg l−1 (4.44 μM) BA and 40 mg l−1 (296.08 μM) adenine. Regnerated plants grown in soil under greenhouse conditions reached maturity and produced seeds. 相似文献
5.
Bopaiah A. Biddanda Dwight F. Coleman Thomas H. Johengen Steven A. Ruberg Guy A. Meadows Hans W. Van Sumeren Richard R. Rediske Scott T. Kendall 《Ecosystems》2006,9(5):828-842
Dissolution of the Silurian-Devonian aquifer in the Lake Huron Basin has produced several karst formations in the bedrock
(sinkholes), through which groundwater emerges onto the lake floor. During September 2003, we explored a recently discovered
submerged sinkhole ecosystem (55 m × 40 m × ∼1 m) located at a depth of 93 m with a remotely operated vehicle (ROV) equipped
with a conductivity-temperature-depth (CTD) system, an acoustic navigational system, a video camera, and a water sampling
system. In addition to two morphotypes of benthic mats, a 1–2 m thick visibly cloudy near-bottom nepheloid-like layer (sinkhole
plume) with a strong hydrogen sulfide odor prevailed just above the seepage area of clear water. Relative to lake water, water
samples collected within the sinkhole plume were characterized by slightly higher (by 4°C) temperatures, very high levels
of chloride (up to 175 mg l−1) and conductivity (1,700 μS cm−1), as well as extremely high concentrations of sulfate (1,400 mg l−1), phosphorus (3 mg l−1) and particulate organic matter (400 mg C l−1). Compared to background lake water, sinkhole plume water was characterized by approximately twofold lower C:N ratios and
tenfold higher levels of dissolved organic carbon, bacterial biomass as well as heterotrophic bacterial production. Significant
uptake of 14C-bicarbonate in dark incubations provided preliminary evidence for occurrence of chemosynthesis, possibly mediated by specialized
Bacteria and Archea present in this submerged sinkhole ecosystem in the Laurentian Great Lakes. 相似文献
6.
Why biomanipulation can be effective in peaty lakes 总被引:1,自引:1,他引:0
The effects of fish stock reduction (biomanipulation) was studied in an 85 ha shallow peaty turbid lake. The lake cleared
in a 4-week period in April–May 2004, which demonstrated that biomanipulation can be effective in peaty lakes. We demonstrated
that it is possible to reduce the fish stock to <25 kg ha−1 benthivorous fish and <15 kg ha−1 planktivorous fish, sufficiently low to switch the lake from a turbid to a clear state. Knowledge of lake morphology, fish
stock, fish behaviour, and a variety of fishing methods was necessary to achieve this goal. It is expected that continuation
of fisheries to remove young of the year planktivorous species is needed for several years, until macrophytes provide sufficient
cover for zooplankton and can compete with phytoplankton. Cladocerans developed strongly after fish removal. The clearing
of the lake coincided with a sudden decrease of filamentous cyanobacteria and suspended detritus, and a strong increase of
Bosmina. We assume that Bosmina was able to reduce filamentous prokaryotes and detritus. After the disappearance of the cyanobacteria, Bosmina disappeared too. After the clearing of the lake Daphnia dominated in zooplankton and apparently was able to keep phytoplankton levels low. In our case, wind resuspension did not
prevent biomanipulation from being successful. No correlation between windspeed and turbidity was found, neither in an 85
ha nor in a 230 ha shallow peaty lake. Regression analysis showed that on average 50% of the amount of suspended detritus
can be explained by resuspension by fish and 50% by phytoplankton decomposition. The main goal of this biomanipulation experiment,
clear water and increased submerged plant cover in a shallow peaty lake, was reached. 相似文献
7.
Toshiya Katano Shin-ichi Nakano Hiroyuki Ueno Osamu Mitamura Kaori Anbutsu Masayuki Kihira Yasuhiro Satoh Takeshi Satoh Valentin V. Drucker Yuji Tanaka Yuki Akagashi Masahito Sugiyama 《Limnology》2008,9(3):243-250
The abundance and composition of phytoplankton were investigated at six stations along a transect from the Barguzin River
inflow to the central basin of Lake Baikal in August 2002 to clarify the effect of the river inflow on the phytoplankton community
in the lake. The water temperature in the epilimnion was high near the shore at Station 1 (17.3°C), probably due to the higher
temperature of the river water, and gradually decreased offshore at Station 6 (14.5°C). Thermal stratification developed at
Stations 2–6, and a thermocline was observed at a 17–22-m depth at Stations 2–4 and an 8–12-m depth at Stations 5 and 6. The
concentrations of nitrogen and phosphorus nutrients in the epilimnion at all stations were <1.0 μmol N l−1 and <0.16 μmol P l−1, respectively. Relatively high concentrations of nutrients (0.56–7.38 μmol N l−1 and 0.03–0.28 μmol P l−1) were detected in the deeper parts of the euphotic zone. Silicate was not exhausted at all stations (>20 μmol Si l−1). The chlorophyll a (chl. a) concentration was high (>10 μg l−1) near the shore at Station 1 and low (<3 μg l−1) at five other stations. The <2 μm fraction of chl. a in Stations 2–6 ranged between 0.80 and 1.85 μg l−1, and its contribution to total chl. a was high (>60%). In this fraction, picocyanobacteria were abundant at all stations and ranged between 5 × 104 and 5 × 105 cells ml−1. In contrast, chl. a in the >2 μm fraction varied significantly (0.14–11.17 μg l−1), and the highest value was observed at Station 1. In this fraction, the dominant phytoplankton was Aulacoseira and centric diatoms at Station 1 and Cryptomonas, Ankistrodesmus, Asterionella, and Nitzschia at Stations 2–6. The present study demonstrated the dominance of picophytoplankton in the pelagic zone, while higher abundance
of phytoplankton dominated by diatoms was observed in the shallower littoral zone. These larger phytoplankters in the littoral
zone probably depend on nutrients from the Barguzin River. 相似文献
8.
The effects of silicate and glucose on growth and eicosapentaenoic acid (EPA) production by the diatom Nitzschia laevis were studied. By alternately altering the concentrations of silicate (2.7–64 mg l−1) and glucose (1–40 g l−1) in the medium, the highest cell dry weight (ca. 5.5 g l−1) was obtained at 20 g l−1 glucose and 32 mg l−1 silicate, while the highest specific growth rate (ca. 0.65 day−1) was obtained at a relatively low glucose concentration (5 g l−1) and high silicate concentrations (32–64 mg l−1). At glucose levels of 5 and 20 g l−1, EPA content was higher with lower silicate concentrations (2.7 and 16 mg l−1 silicate, respectively), while at a silicate level of 16 mg l−1, higher glucose concentrations (20–40 g l−1) facilitated EPA formation. The highest EPA yield (131 mg l−1) was obtained at 20 g l−1 glucose and 32 mg l−1 silicate, while the highest EPA productivity (15.1 mg l−1 day−1) was obtained at 20 g l−1 glucose and 64 mg l−1 silicate. Journal of Industrial Microbiology & Biotechnology (2000) 25, 218–224.
Received 08 May 2000/ Accepted in revised form 21 July 2000 相似文献
9.
Priscila Kienteca Lange Denise Rivera Tenenbaum Elisabete de Santis Braga Lúcia S. Campos 《Polar Biology》2007,30(11):1483-1492
Microphytoplankton populations were studied in shallow coastal water (<60 m) near the Brazilian Antarctic Station Comandante
Ferraz (EACF) and three reference areas in Admiralty Bay in early and late summer (2002–2003). Phytoplankton was diverse (113
taxa), but not abundant (103 cells l−1). The highest abundances (>104 cells l−1) were caused by pennate benthic diatoms (Fragilaria striatula Lyngbye) that occurred mainly in early summer, associated with the presence of ice. In late summer, when the water temperature
(−0.4 to 1.5°C), salinity (34 to 35), and phosphate (2.6 to 4.5 μmol l−1) were highest and the dissolved oxygen was lowest (6.4 to 2.9 ml l−1), centric diatoms (Thalassiosira spp.) were more abundant, suggesting an influence of oceanic waters. Phytoplankton abundance (≤102 cells l−1) and chlorophyll a concentrations (0.22 μg l−1) were lowest close to EACF. Pennate diatoms were dominant close to shore and in surface waters elsewhere, probably because
of ice melting or sediment resuspension caused by water mixing. 相似文献
10.
T. Chakbavarty J. G. Norcini J. H. Aldrich R. S. Kalmbacher 《In vitro cellular & developmental biology. Plant》2001,37(5):550-554
Summary Creeping bluestem (Schizachyrium scoparium (Michx.) Nash var. stoloniferum (Nash) J. Wipff) embryogenic callus growing on solid medium was used to establish a cell suspension culture in Murashige
and Skoog (MS) basal medium supplemented with 1.5 mg l−1 (6.8 μM) 2,4-dichlorophenoxyacetic acid (2,4-D), 0.2 mg l−1 (0.88 μM) 6-benzylaminopurine (BA), 0.5 mg l−1 (1.4 μM) zeatin, 0.2 mg l−1 (0.58 μM) gibberellic acid (GA3), and 10% (v/v) of coconut water (CW). Pro-embryos from suspension culture matured on semi-solid MS medium in about 18 wk,
and were then cultured on semi-solid MS medium without growth regulators for 2–3 wk. Shoots were regenerated on MS basal medium
supplemented with 3.0 mg L−1 (13.6 μM) 2,4-D, 1.0 mg l−1 (4.4 μM) BA, 1.0 mg l−1 (2.9 μM) GA3, 0.5 mg l−1 (2.7 μM) 1-naphthaleneacetic acid (NAA), 500 mg l−1 easein hydrolysate, and 10% (v/v) CW. Rooted plantlets were successfully accelimatized to greenhouse and outdoor conditions.
Using this protocol, it would be possible to produce at least 1300 fully acclimatized plantlets annually. 相似文献
11.
Temporal patterns of primary production in a large ultra-oligotrophic Antarctic freshwater lake 总被引:3,自引:1,他引:2
A large ultra-oligotrophic Antarctic freshwater lake, Crooked Lake, was investigated between January 1993 and November 1993.
The water column supported a small phytoplankton community limited by temperature, nutrient availability and, seasonally,
by low photosynthetically active radiation. Chlorophyll a concentrations were consistently low (<1 g l−1) and showed no obvious seasonal patterns. Production rates were low, ranging from non-detectable to 0.56 g C l−1 h−1, with highest rates generally occurring towards the end of the austral winter and in spring. The pattern of carbon fixation
indicated that the phytoplankton was adapted to low light levels. Chlorophyll a specific photosynthetic rates (assimilation numbers) ranged from non-detectable to 1.27 gC (g chlorophyll a)−1 h−1. Partitioning of photosynthetic products revealed carbon incorporation principally into storage products such as lipids at
high light fluxes with increasing protein synthesis at depth. With little allochthonous input the data suggest that lake dynamics
in this Antarctic system are driven by phytoplankton activity.
Received: 21 February 1997 / Accepted: 18 May 1997 相似文献
12.
We compared on eight dates during the ice-free period physicochemical properties and rates of phytoplankton and epipelic primary
production in six arctic lakes dominated by soft bottom substrate. Lakes were classified as shallow ( < 2.5 m), intermediate in depth (2.5 m < < 4.5 m), and deep ( > 4.5 m), with each depth category represented by two lakes. Although shallow lakes circulated freely and intermediate and
deep lakes stratified thermally for the entire summer, dissolved oxygen concentrations were always >70% of saturation values.
Soluble reactive phosphorus and dissolved inorganic nitrogen (DIN = NO3
−–N + NH4
+–N) were consistently below the detection limit (0.05 μmol l−1) in five lakes. However, one lake shallow lake (GTH 99) periodically showed elevated values of DIN (17 μmol l−1), total-P (0.29 μmol l−1), and total-N (33 μmol l−1), suggesting wind-generated sediment resuspension. Due to increased nutrient availability or entrainment of microphytobenthos,
GTH 99 showed the highest average volume-based values of phytoplankton chlorophyll a (chl a) and primary production, which for the six lakes ranged from 1.0 to 2.9 μg l−1 and 0.7–3.8 μmol C l−1 day−1. Overall, however, increased resulted in increased area-based values of phytoplankton chl a and primary production, with mean values for the three lake classes ranging from 3.6 to 6.1 mg chl a m−2 and 3.2–5.8 mmol C m−2 day−1. Average values of epipelic chl a ranged from 131 to 549 mg m−2 for the three depth classes, but levels were not significantly different due to high spatial variability. However, average
epipelic primary production was significantly higher in shallow lakes (12.2 mmol C m−2 day−1) than in intermediate and deep lakes (3.4 and 2.4 mmol C m−2 day−1). Total primary production (6.7–15.4 mmol C m−2 day−1) and percent contribution of the epipelon (31–66%) were inversely related to mean depth, such that values for both variables
were significantly higher in shallow lakes than in intermediate or deep lakes.
Handling editor: L. Naselli-Flores 相似文献
13.
Summary A procedure for the regeneration of complete plantlets of Tylophora indica from cultured leaf callus via somatic embryogenesis is described. Callus induction from leaf explants was on Murashige and
Skoog (MS) medium with different concentrations of 2,4-dichlorophenoxyacetic acid (2.4-D; 0.03–3 mg l−1; 0.0–13.56 μM) and kinetin (Kn; 0.01 mg l−1; 0.05 μM). The best response for callus induction was obtained on MS medium containing 2 mg l−1 (9.04 μM) 2.4-D and 0.01 mg l−1 (0.05 μM) Kn. After two subeultures on the same medium the embryogenic callus was transferred to MS medium with different concentrations
of the cytokinin, 6-benzyladenine (0.5–3 mg l−1; 2.22–13.32 μM) and 2-isopentenyladenine (2ip; 0.53 mg l−1; 2.46–14.76 μM) along with 0.01 mg l−1 (0.05 μM) indole-3-butyric acid (IBA) for somatic embryo development and maturation. MS medium with 2 mg l−1 (9.84 μM) 2ip produced the maximum number of mature somatic embryos. The mature embryos were bipolar and on transfer to MS basal medium
produced complete plantlets. After hardening the regenerants were planted in the Gudalur forests of Western Ghats. Total DNA
was extracted from 14 regenerants and the mother plant. Random amplified polymorphic, DNA (RAPD) analysis was carried out
using 20 arbitrary oligonucleotides. The amplification products were monomorphic among all the plants revealing the genetic
homogeneity and true-to-type nature of the regenerants. 相似文献
14.
Daniela R. de Figueiredo Mário J. Pereira António Correia 《World journal of microbiology & biotechnology》2010,26(6):1067-1077
At the present time, there is still a lack of information about environmental parameters modulating variations on bacterial
diversity in temperate lakes, particularly from Portugal. Fermentelos Lake (Central Portugal) is a shallow water body that
sustains an important wetland area. The strong nutrient inputs from agriculture and industrial runoffs have led to its current
eutrophic status. The present work aimed to understand which factors modulate the seasonal bacterioplankton diversity at this
lake using 16S rRNA PCR-denaturing gradient gel electrophoresis (DGGE) and multivariate analysis. Environmental data demonstrated eutrophic features
throughout all samples with nitrate concentrations reaching 12.0 mg N (NO3
−) l−1 in March 2006, while the highest conductivity (609 μS cm−1), soluble reactive phosphorus (0.37 mg l−1), total suspended solids (87.2 mg l−1) and chlorophyll a (286.6 μg l−1) levels were recorded in August 2007. Over the past two decades there was a general increase in nitrate, pH and conductivity
levels at this lake, suggesting the eutrophication process is still in progress. Multivariate analysis showed that summer
versus winter DGGE patterns could be established for bacterial assemblages and were mainly defined by water temperature and
chlorophyll a. Actinobacteria were dominant throughout the study period although a general preference for higher temperature, pH, total suspended solids,
conductivity, soluble reactive phosphorus (SRP) and chlorophyll a levels was observed. The highest concentrations of nitrogen sources were related to Bacteroidetes and phototrophic eukaryote (cryptophycean) dominance. The expansion of Betaproteobacteria, Alphaproteobacteria and Cyanobacteria phylotypes was generally associated to high temperature, pH, conductivity and SRP values. 相似文献
15.
Neslihan Balkis 《Aquatic Ecology》2009,43(2):249-270
Seasonal changes in the microphytoplankton assemblages were examined in the coastal zone of Bozcaada Island with regard to
some major physical and chemical variables. Samples were collected from May 2000 to December 2001 at four stations. A total
of 108 dinoflagellates, 102 diatoms, 1 chrysophycean, 3 dictyochophycean, and 1 prasinophycean species were identified and
quantified during the study period. Diatoms and dinoflagellates were the most important in terms of species number and abundance.
The maximum values of total microphytoplankton were observed at 0.5 m depth (46.2 × 103 cells l−1 at st. 3) in May as this was the month when the diatom Pseudo-nitzschia pungens bloomed. Chlorophyll (chl) a concentration ranged between 0.08 (August) and 0.78 μg l−1 (February). May was another important month in which chlorophyll a increased (0.41–0.47 μg l−1). Species diversity values (H′log2) ranged from 1.66 bits (June, 20 m) to 4.11 bits (November, 0.5 m). The increase was attributed to a more balanced distribution
of abundance among species. The amounts of nitrate + nitrite (0.6−3.7 μg-at N l−1), phosphate (0.2−0.6 μg-at P l−1) and silicate (0.7−2.5 μg-at Si l−1) were recorded on each sampling occasion. Nutrient concentrations and chl a values of the research area were found to be poorer than those of the many other coastal areas in the northeastern Mediterranean.
The mean atomic ratio of nitrogen to phosphorus varied from 1.3 (June) to 12.9 (February). This ratio was lower than the Redfield
ratio of 16 for ocean phytoplankton, and phytoplankton was potentially limited by nitrogen for most of the months. The result
of this study confirms and emphasizes the oligotrophic nature of the eastern Mediterranean. 相似文献
16.
Soy molasses as fermentation substrate for production of butanol using Clostridium beijerinckii BA101 总被引:2,自引:0,他引:2
Qureshi N Lolas A Blaschek HP 《Journal of industrial microbiology & biotechnology》2001,26(5):290-295
Spray-dried soy molasses (SDSM) contains the sugars dextrose, sucrose, fructose, pinitol, raffinose, verbascose, melibiose,
and stachyose. Of the 746 g kg−1 total sugars in SDSM, 434 g kg−1 is fermentable using Clostridium beijerinckii BA101. SDSM was used to produce acetone, butanol, and ethanol (ABE) by C. beijerinckii BA101 in batch cultures. Using 80 g l−1 SDSM, 10.7 g l−1 ABE was produced in P2 medium. Higher concentrations of SDSM resulted in poor solvent production due to the presence of excessive
salt and inhibitory components. C. beijerinckii BA101 in SDSM at 80 g l−1 concentration produced 22.8 g l−1 ABE when supplemented with 25.3 g l−1 glucose. SDSM contains 57.4 g kg−1 mineral ash and 2% tri-calcium phosphate. Tri-calcium phosphate up to 43.1 g l−1 was not inhibitory and at a tri-calcium phosphate concentration of 28.8 g l−1, the culture produced more solvents (30.1 g l−1) than the control experiment (23.8 g l−1). In contrast, sodium chloride was a strong inhibitor of C. beijerinckii BA101 cell growth. At a concentration of 10 g l−1 sodium chloride, a maximum cell concentration of 0.6 g l−1 was achieved compared to 1.7 g l−1 in the control experiment. The effects of two salts on specific growth rate constant (μ) and specific rate of ABE production (ν) for C. beijerinckii BA101 were examined. Journal of Industrial Microbiology & Biotechnology (2001) 26, 290–295.
Received 20 September 2000/ Accepted in revised form 16 February 2001 相似文献
17.
V. M. Gorlenko S. P. Buryukhaev E. B. Matyugina S. V. Borzenko Z. B. Namsaraev I. A. Bryantseva E. N. Boldareva D. Yu. Sorokin B. B. Namsaraev 《Microbiology》2010,79(3):390-401
The physicochemical properties, species composition, and vertical distribution of microorganisms in the water column, shoreline
microbial mat, and small shoreline mud volcanoes of the stratified soda Lake Doroninskoe were investigated in September 2007.
The lake is located in the Transbaikal region, in the permafrost zone (51°25′N; 112°28′E). The maximal depth of the contemporary
lake is about 6 m, the pH value of the water is 9.72, and the water mineralization in the near-bottom horizon is 32.3 g l−1. In summer, the surface oxygen-containing horizon of the water column becomes demineralized to 26.5 g l−1; at a depth of 3.5–4.0 m, an abrupt transition occurs to the aerobic zone containing hydrosulfide (up to 12.56 g l−1). Hydrosulfide was also detected in trace quantities in the upper water horizons. The density stratification of the water
column usually ensures stable anaerobic conditions until the freezing period (November and December). The primary production
of oxygenic phototrophs reached 176–230 μg l−1. High rates of dark CO2 assimilation (61–240 μg l−1) were detected in the chemocline. Within this zone, an alkaliphilic species of sulfur-oxidizing bacteria of the genus Thioalkalivibrio was detected (104 cells ml−1). Lithoheterotrophic bacteria Halomonas spp., as well as bacteriochlorophyll a-containing aerobic anoxygenic phototrophic bacteria (AAP) Roseinatronobacter sp. capable of thiosulfate oxidation, were isolated from samples collected from the aerobic zone (0–3 m). The water transparency
in September was extremely low; therefore, no visible clusters of anoxygenic phototrophic bacteria (APBs) were detected at
the boundary of the hydrosulfide layer. However, purple sulfur bacteria which, according to the results of the 16S rRNA gene
analysis, belong to the species Thioalkalicoccus limnaeus, Ectothiorhodospira variabilis, “Ect. magna,” and Ect. shaposhnikovii, were isolated from samples of deep silt sediments. Ect. variabilis and Ect. shaposhnikovii were the major APB species in the shoreline algo-bacterial mat. The halotolerant bacterium Ect. shaposhnikovii, purple nonsulfur bacteria of the genus Rhodobacter, and AAP of Roseococcus sp. were isolated from the samples collected from mud volcanoes. All these species are alkaliphiles, moderate halophiles,
or halotolerant microorganisms. 相似文献
18.
Lactobacillus delbrueckii was grown on sugarcane molasses, sugarcane juice and sugar beet juice in batch fermentation at pH 6 and at 40°C. After 72 h,
the lactic acid from 13% (w/v) sugarcane molasses (119 g total sugar l−1) and sugarcane juice (133 g total sugar l−1) was 107 g l−1 and 120 g l−1, respectively. With 10% (w/v) sugar beet juice (105 g total sugar l−1), 84 g lactic acid l−1 was produced. The optical purities of d-lactic acid from the feedstocks ranged from 97.2 to 98.3%. 相似文献
19.
Ecology of Dictyosphaerium pulchellum Wood (Chlorophyta, Chlorococcales) in a shallow, acid, forest lake 总被引:1,自引:0,他引:1
This study relates to the ecology of Dictyosphaerium pulchellum Wood in Delamere Lake in Cheshire, UK. Dictyosphaerium pulchellum is a cosmopolitan, green colonial phytoplankton species that occasionally forms dense, monospecific populations in lakes.
Delamere Lake is a small, shallow, acid lake (mean pH, 4.5) with very high phytoplankton biomass (annual mean chlorophyll
a, 290 μg l−1) and devoid of any significant cladoceran population, the efficient grazers of phytoplankton. A predominantly unicellular
form of D. pulchellum was the dominant species in Lake Delamere, and it comprised on average ca. 80% (maximum >99%) of the lake phytoplankton biovolume.
Laboratory and lake experiments were conducted on this species showed that its pH tolerance varied between 2.4 and 10.7, and
its optimum tolerance range between 3.3 and 8.5 depending on other environmental variables. Low pH was not responsible for
the unicellular habit of this alga, but a very high nutrient regime could be an important factor. Bioassays revealed that
in Delamere Lake this species was limited by nitrogen, but nitrogen did not hamper high growth in the lake. Dictyosphaerium pulchellum can persist at low light levels, tolerate CO2-deficiency and can grow in polyhumic water with water colour around 300 mg Pt l−1, but probably not in darker waters. The dominance of D. pulchellum in Delamere Lake is apparently due to a combination of several factors: its ability to tolerate both low pH and high turbidity,
exploit high nutrient conditions, absence of effective grazing pressure by zooplankton and being a superior competitor. 相似文献
20.
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