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1.
In an attempt to assess bacterioplankton production and growth yieldunder low temperature conditions and to compare bacterioplankton withphytoplankton production in the ice-covered water column of the shallowNeusiedler See, outdoor measurements under near in situ conditions wereperformed during the winter of 1995/96. During the investigation period,mean chlorophyll (Chl) a concentration was 21.03 ± 14.95 µg Chla l-1. Phytoplankton primary production integrated over thewater column ranged from 1.35 to production integrated over the water columnranged from 1.35 to 4.23 mg C m-2 d-1 (mean± SD = 2.46 ± 1.06 mg C m-2d-1). Bacterial abundance varied from 20 to 40×105 ml-1 for most of the investigationperiod and increased by the end of March concomitantly with the increase intemperature from 1.3 to 6.3 °C within 5 days. Mean bacterial productionwas 15.3 ± 12.8 µg C l-1 d-1(range: 3.0 to 41.7 µg C l-1 d-1) and meanbacterial growth rate 0.23 ± 0.16 d-1 following closelythe pattern in bacterial production. DOC concentration declined linearlyfrom 20.7 mg C l-1 to 16.45 mg C l-1 over the 4months period of ice cover. The contribution of humic substances to thetotal DOC pool declined from 43.6% at the end of November to37.3% at the end of March. Calculated on an area basis, phytoplanktonproduction amounted to only 16% of bacterial production which makesit unlikely that phytoplankton supply substrate for bacterioplankton growthin significant quantities when the lake is ice covered. From the observeddecline in DOC over the investigation period and assuming only negligibleinput of DOC from other sources we calculated an average DOC uptake by thebacterioplankton community of 47.5 µg C l-1d-1 resulting in a bacterial growth efficiency of 15.9%for the ice covered conditions. Based on the growth efficiency we estimatethat pelagic primary production amounts to 2.8% of the bacterialcarbon demand. This might indicate that the bacterioplankton in NeusiedlerSee sustain their high growth rates at low temperatures (<2°C formost of the investigation period) by using probably the DOC originating fromthe previous season. This DOM stems most likely from the decay of the reedPhragmites australis and its epiphytes and, probably of minor importance,from phytoplankton leachates. 相似文献
2.
José Juan Barrera-Alba Sônia Maria Flores Gianesella Gleyci Aparecida Oliveira Moser Flávia Marisa Prado Saldanha-Corrêa 《Hydrobiologia》2008,598(1):229-246
Heterotrophic bacterial and phytoplankton biomass, production, specific growth rates and growth efficiencies were studied
in July 2001 and January 2002 during both spring and neap tides, along a tidal cycle, at three sites in a subtropical estuary.
Major freshwater inputs located in the Northern region led to differences in both phytoplankton and bacterioplankton biomass
and activity along the estuary. While in the Northern region phytoplankton is light-limited, with mean phytoplankton production
(PP) between 1.1 and 1.9 μg C l−1 h−1 and mean specific growth rates (PSG) between 0.14 and 0.16 d−1, the Southern region registered values as high as 24.7 μg C l−1 h−1 for PP and 2.45 d−1 (mean PP between 3.4 and 7.3 μg C l−1 h−1; mean PSG between 0.28 and 0.57 d−1). On the other hand, maximum bacterial production (BP: 63.8 μg C l−1 h−1) and specific growth rate (BSG: 32.26 d−1) were observed in the Northern region (mean BP between 3.4 and 12.8 μg C l−1 h−1; mean BSG between 1.98 and 6.67 day−1). These bacterial activity rates are among the highest recorded rates in estuarine and coastal waters, indicating that this
system can be highly heterotrophic, due to high loads of allochthonous carbon (mainly derived from mangrove forest). Our results
also showed that, despite that BP rates usually exceeded PP, in the Southern region BP may be partially supported (∼45%) by
PP, since a significant regression was observed between BP and PP (r = 0.455, P < 0.001).
Handling editor: P. Viaroli 相似文献
3.
J. Laybourn-Parry Mark R. James Diane M. McKnight John Priscu Sarah A. Spaulding Russell Shiel 《Polar Biology》1996,17(1):54-61
Samples collected from Lake Fryxell, southern Victoria Land, Antarctica in January 1992 and 1994 were analysed for the abundance
of bacterioplankton and the diversity and abundance of protistan plankton. At the times of sampling, 14 ciliate species and
10 species of autotrophic flagellate were recorded. The samples contained two species of rotifer (Philodina spp.), which formed the first record of planktonic metazoans in the Dry Valley lakes of this region of Antarctica. Bacterial
concentrations ranged between 1.0 and 3.8×108 l-1 in the upper oxic waters increasing to 20×108 l-1 in the anoxic waters. Heterotrophic flagellates decreased in abundance down the oxygenated water column, disappearing completely
at 9 m, and ranged between 0.28 and 7.39×105 l-1 in abundance. Autotrophic flagellates were much more abundant exhibiting a number of distinct peaks down the water column
(1.89–25.3×108 l-1). The ciliated protozoa were very abundant (up to 7720 l-1) in relation to flagellate and bacterial numbers, typical of oligotrophic lakes world-wide. The distribution of the protistan
plankton showed marked zonation, probably in response to the differing salinity and temperature gradients in the water column.
Possible trophic interactions are discussed and comparisons with other continental Antarctic lakes made.
Received: 29 November 1995/Accepted: 18 February 1996 相似文献
4.
Russell T. Bell Rolf Erikson Kathleen Vammen Maria Helena Vargas Argentina Zelaya 《Aquatic Ecology》1991,25(2):145-149
The biomass and production (thymidine incorporation) of heterotrophic bacterioplankton has been assessed from July, 1988, to October, 1989. in Lake Xolotlán, Nicaraqua. Bacterial abundance was high, 2–3.1010 cells.l–1, and bacterial biomass averaged ca. 0.75 mg C.l–1, or roughly 20% of the partivculate organic carbon. Bactrial production averaged between 3.5–5 g C.l–1.h–1 and on a areal basis was 650–959 mg C.m–2.d–1 or 13–20% ofthe primary production. Although bacterial production (volumetric basis) was typical for eutrophic lakeks, the bacterial specific growth rate was low, the bacteial population doubling time was ca. 1 week, perhaps indicating that there was a low grazing pressure on the bacteria. 相似文献
5.
Laura Alonso-Sáez Evaristo Vázquez-Domínguez Clara Cardelús Jarone Pinhassi M. Montserrat Sala Itziar Lekunberri Vanessa Balagué Maria Vila-Costa Fernando Unrein Ramon Massana Rafel Simó Josep M. Gasol 《Ecosystems》2008,11(3):397-409
Data from several years of monthly samplings are combined with a 1-year detailed study of carbon flux through bacteria at
a NW Mediterranean coastal site to delineate the bacterial role in carbon use and to assess whether environmental factors
or bacterial assemblage composition affected the in situ rates of bacterial carbon processing. Leucine (Leu) uptake rates
[as an estimate of bacterial heterotrophic production (BHP)] showed high interannual variability but, on average, lower values
were found in winter (around 50 pM Leu−1 h−1) as compared to summer (around 150 pM Leu−1 h−1). Leu-to-carbon conversion factors ranged from 0.9 to 3.6 kgC mol Leu−1, with generally higher values in winter. Leu uptake was only weakly correlated to temperature, and over a full-year cycle
(in 2003), Leu uptake peaked concomitantly with winter chlorophyll a (Chl a) maxima, and in periods of high ectoenzyme activities in spring and summer. This suggests that both low molecular weight
dissolved organic matter (DOM) released by phytoplankton, and high molecular weight DOM in periods of low Chl a, can enhance BHP. Bacterial respiration (BR, range 7–48 μg C l−1 d−1) was not correlated to BHP or temperature, but was significantly correlated to DOC concentration. Total bacterial carbon
demand (BHP plus BR) was only met by dissolved organic carbon produced by phytoplankton during the winter period. We measured
bacterial growth efficiencies by the short-term and the long-term methods and they ranged from 3 to 42%, increasing during
the phytoplankton blooms in winter (during the Chl a peaks), and in spring. Changes in bacterioplankton assemblage structure (as depicted by denaturing gradient gel electrophoresis
fingerprinting) were not coupled to changes in ecosystem functioning, at least in bacterial carbon use. 相似文献
6.
Bacterioplankton growth, grazing mortality and quantitative relationship to primary production in a humic and a clearwater lake 总被引:8,自引:0,他引:8
Bacterial growth and grazing mortality were estimated from Mayto October in two south Swedish oligotrophic lakes, one beinga clearwater lake (water colour 510 mg Pt l1 DOC2.93.4 mg l1, Secchi disk depth 5.09.4m) and the other a humic, brownwater lake (water colour 105165mg Pt l1, DOC 13.722.7mg l1, Secchi diskdepth 1.32.1 m). Specific rates of growth and grazingmortality were generally similar for both lakes. However, theabundance of bacteria was consistently 23 times higherin the water of the humic lake, suggesting that the total productionand consumption of bacterial cells were also higher than inthe dearwater lake. The ratio of bacterial secondary productionto primary production was higher in the humic lake than in theclearwater lake, indicating that the bacterioplankton of thehumic lake utilize allochthonous substrates, in addition tosubstrates originating from autochthonous primary production.Most of the bacterial loss in both lakes could be attributedto small protozoan grazers. This implies that allochthonousand autochthonous organic carbon fixed by bacterioplankton isless important in terms of carbon flow to higher trophic levelsthan would be expected if macrozooplankton were the dominantbacterivores, providing a more direct and efficient transferof carbon to larger organisms. 相似文献
7.
Seasonal change in the proportion of bacterial and phytoplankton production along a salinity gradient in a shallow estuary 总被引:2,自引:2,他引:0
We intended to evaluate the relative contribution of primary production versus allochthonous carbon in the production of bacterial biomass in a mesotrophic estuary. Different spatial and temporal ranges were observed in the values of bacterioplankton biomass (31–273 g C l–1) and production (0.1–16.0 g C l–1 h–1, 1.5–36.8 mg C m–2 h–1) as well as in phytoplankton abundance (50–1700 g C l–1) and primary production (0.1–512.9 g C l–1 h–1, 1.5–512.9 mg C m–2 h–1). Bacterial specific growth rate (0.10–1.68 d–1) during the year did not fluctuate as much as phytoplankton specific growth rate (0.02–0.74 d–1). Along the salinity gradient and towards the inner estuary, bacterio- and phytoplankton biomass and production increased steadily both in the warm and cold seasons. The maximum geographical increase observed in these variables was 12 times more for the bacterial community and 8 times more for the phytoplankton community. The warm to cold season ratios of the biological variables varied geographically and according to these variables. The increase at the warm season achieved its maximum in the biomass production, particularly in the marine zone and at high tide (20 and 112 times higher in bacterial and phytoplankton production, respectively). The seasonal variation in specific growth rate was most noticeable in phytoplankton, with seasonal ratios of 3–26. The bacterial community of the marine zone responded positively – generating seasonal ratios of 1–13 in bacterial specific growth rate – to the strong warm season increment in phytoplankton growth rate in this zone. In the brackish water zone where even during the warm season allochthonous carbon accounted for 41% (on average) of the bacterial carbon demand, the seasonal ratio of bacterial specific growth rate varied from about 1 to 2. During the warm season, an average of 21% of the primary production was potentially sufficient to support the whole bacterial production. During the cold months, however, the total primary production would be either required or even insufficient to support bacterial production. The estuary turned then into a mostly heterotrophic system. However, the calculated annual production of biomass by bacterio- and phytoplankton in the whole ecosystem showed that auto- and heterotrophic production was balanced in this estuary. 相似文献
8.
Influence of the Hydrological Cycle on the Bacterioplankton of an Impacted Clear Water Amazonian Lake 总被引:4,自引:0,他引:4
Abstract
Free-living and attached bacterial population sizes were determined fortnightly from December 1991 to December 1992 in natural
and disturbed areas of an Amazonian clear water lake (Batata Lake, Pará, Brazil) impacted by bauxite tailings. The bacterioplankton
showed distinct patterns during different phases of the hydrological cycle. Total bacterial population size and rates of thymidine
incorporation (measured during high and low water phases) were high during low water, with values ranging from 3.3 × 105 to 1.1 × 106 cells ml−1, and from 0.28 to 4.01 μg C l−1 h−1, respectively. The population size of free-living bacteria was larger at the natural station, while no differences were observed
between attached bacterial populations at both stations. However, production and turnover rate of attached bacteria were high
at the disturbed area. During low water, bacterial growth appeared to be driven mainly by the input of dissolved organic carbon
(DOC) from phytoplankton origin. During high water, bacterial abundance was reduced, probably as the result of dilution and
the input of less labile DOC from floodplains. The presence of bauxite tailings seems to influence bacterial dynamics in an
indirect way, probably due to shading of phytoplankton cells and, hence, reducing the DOC supply for bacterial growth. This
study, the first on the microbial ecology of an Amazonian clear water lake, demonstrated that water level variations exert
a strong influence on the bacterioplankton dynamics.
Received: 9 January 1996; Accepted 6 November 1996 相似文献
9.
Picophytoplankton biomass, community structure and productivity in the Great Astrolabe Lagoon, Fiji 总被引:4,自引:0,他引:4
Phytoplankton biomass, community structure and productivity of the Great Astrolabe lagoon and surrounding ocean were studied
using measurements of chlorophyll concentration and carbon uptake. The contribution of picophytoplankton to biomass, productivity
and community structure was estimated by size fractionation, 14C-incubation and flow cytometry analysis. Picoplankton red fluorescence was demonstrated to be a proxy for chlorophyll <3 μm.
Consequently, the percentage contribution to chl a<3 μm from each picoplankton group could be calculated using regression estimated values of ψ
i
(fg chl a per unit of red fluorescence). In the lagoon, average chlorophyll concentration was 0.8 mg m-3 with 45% of phytoplankton <3 μm. Primary production reached 1.3 g C m-2 day-1 with 53% due to phytoplankton <3 μm. Synechococcus was the most abundant group at all stations, followed by Prochlorococcus and picoeukaryotes. At all stations, Prochlorococcus represented less than 4% of the chl a <3 μm, Synechococcus between 85 and 95%, and Picoeukaryotes between 5 and 10%. In the upper 40 m of surrounding oceanic waters, phytoplankton
biomass was dominated by the >3 μm size fraction. In deeper water, the <1 μm size fraction dominated. Prochlorococcus was the most abundant picoplankton group and their contributions to the chlorophyll a<3 μm were close to that of the picoeukaryotes (50% each).
Accepted: 27 May 1999 相似文献
10.
Concentrations of plankton, suspended particles 0.74–87 μm equivalent spherical diameter and dissolved organic carbon (DOC)
were measured from May to February at an Antarctic coastal site. Bacteria-sized particles 0.74–1 μm diameter, and bacterial
cells and heterotrophic protists all exhibited a seasonal minimum during winter and maxima in summer. Bacteria composed <10%
of the bacteria-sized particles. Release of autotrophic protists from the ice caused water column biomass of autotrophs to
reach maximum concentrations in October and November, but maximum cell concentration in the water column was reached in January.
Microheterotroph biomass weakly reflected the release of the ice algal community but reached maximum concentration during
the water column bloom in January. Total DOC concentrations varied from 0.36 mg C l−1 in July to 3.10 mg C l−1 in October, with a yearly average of 1.51 mg C l−1. Ultrafiltration of DOC revealed that the molecular weight composition of the DOC differed greatly through the year. DOC
<5 kDa molecular weight reached a maximum of 1.25 mg C l−1 in October and accounted for up to 60% of total DOC in July. Concentrations of high molecular weight DOC (>100 kDa) were
highest in July and November, with the DOC (100 kDa–0.5 μm) fraction reaching a maximum of 1.22 mg C l−1 in November and composing 82% of the total DOC in January. Wet chemical oxidation and high-temperature catalytic oxidation
organic carbon analyses were compared. Good correlation was observed between methods during summer but no significant correlation
existed in winter, indicating that winter DOC may be refractory.
Accepted: 21 March 2000 相似文献
11.
The quantitative distribution of viruses and their impact on heterotrophic bacterioplankton were studied in mesotrophic and
eutrophic reservoirs of the Volga and Volga-Baltic waterway. The abundance of planktonic virus particles ranged from 9.4 ×
106 to 120 × 106 ml−1 and was from 2.5 to 9 times greater than the bacterial numbers. Production of virioplankton varied from 2.1 × 106 to 132 × 106 particles (ml day)−1 and the population turnover time values were between 0.3 and 11.6 days. The maximum values of numbers and production of virio-
and bacterioplankton were observed in the eutrophic Ivan’kovo reservoir. Distribution of the viruses in the Volga reservoirs
depended to a significant degree on the number and activity of heterotrophic bacterioplankton. The infected bacteria accounted
for 5.5–33.5% of the total bacterial abundance. Phages were an important factor of bacterial mortality. During July to September
virus-induced bacterial mortality varied between 6.1 and 40.6% (20.2% on average) of daily bacterioplankton production. 相似文献
12.
María Fernanda Adame Ruth Reef Jorge A. Herrera-Silveira Catherine E. Lovelock 《Hydrobiologia》2012,691(1):239-253
Poor water quality affects the biogeochemistry functions and the biological community structure of coastal ecosystems. In this study we investigated the effect of water quality on: (a) The exchange of dissolved organic carbon (DOC) between floodwater and mangrove forests, (b) the abundance of sediment bacteria, (c) the microbial community composition, and (d) the microbial catabolic activity. We selected six mangrove forests that were flooded by creeks with differing water qualities to test for thresholds of nutrient concentrations associated with changes in DOC dynamics and the microbial community. Our results show that in sites flooded by water high in soluble reactive phosphorus (SRP) (>20 μg l−1) and NH4 + (>30 μg l−1) the DOC concentrations in the floodwater were higher than in ebb water, suggesting DOC import by the mangroves. In contrast, in sites flooded by water low in SRP (<20 μg l−1) and NH4 + (<30 μg l−1), DOC concentrations in the floodwater were lower than in the ebb water, suggesting DOC export by the mangroves. Bacterial abundance was higher in sediments with low bulk density, high organic carbon and when flooded by water with low N:P (1–2), but the microbial composition and total catabolic activity assessed using Biolog Ecoplates™ did not differ among sites. The relationship between water quality, microbial communities and DOC exchange suggests that, at least during some periods of the year, poor water quality increases bacterial abundance and modifies DOC exchange of mangrove forests with floodwater and thus, their role in supporting near-shore productivity. 相似文献
13.
The synthesis of poly(3-hydroxyalkanoates) (PHA) by Pseudomonas putida KT2442 growing on long-chain fatty acids was studied in continuous cultures. The effects of the growth rate on the biomass
and polymer concentration were determined and it was found that the PHA concentrations decreased with increasing growth rates.
The highest volumetric productivity was 0.13 g PHA l-1 h-1 at a specific growth rate (μ) of 0.1 h-1. The molecular mass of the polymer remained constant at all growth rates but changes in the monomeric composition of the
PHA synthesized were observed. Variation of the carbon to nitrogen (C/N) ratio of the substrate feed at μ=0.1 h-1 revealed optimal PHA formation at C/N=20 mol/mol. In order to optimize PHA production P. putida KT2442 was cultivated to high cell densities in oxygen-limited continuous cultures. In this way a maximum biomass concentration
of 30 g/l containing approximately 23% PHA was achieved. This corresponds to a volumetric productivity of 0.69 g l-1 h-1.
Received: 14 December 1995 / Received revision: 18 April 1996 / Accepted: 22 April 1996 相似文献
14.
Pierre Lavandier 《Hydrobiologia》1990,207(1):79-86
Bacterioplankton abundance, biomass and production were studied at a central station (35 m depth) from April 1987 to September 1988 in a mesotrophic reservoir. Bacterial production was calculated by the (3H) thymidine method.For the water column, integrated estimates of bacterioplankton abundance ranged from 2.3 109 to 4.6 109 cells l–1, and carbon biomass from 0.037 to 0.068 mg C l–1; the thymidine incorporation rates ranged from 0.8 to 17.2 picomoles l–1 h–1, leading to net bacterial production estimates of less than 0.7 µg C l–1 d–1 in winter to 18 µg C l–1 d–1 in summer. About 55% of the production occurred in the euphotic layers.Over the year, the bacterial carbon requirement represented 90% of the autotrophic production for the whole lake. It was five times lower than autotrophic production in spring, but twice as high in summer. This important temporal lack of balance suggests that not all the spring primary production products are consumed immediately and/or that other carbon sources probably support bacterial growth in summer. 相似文献
15.
Bacterial carbon demand, an important component of ecosystem dynamics in polar waters and sea ice, is a function of both bacterial
production (BP) and respiration (BR). BP has been found to be generally higher in sea ice than underlying waters, but rates
of BR and bacterial growth efficiency (BGE) are poorly characterized in sea ice. Using melted ice core incubations, community
respiration (CR), BP, and bacterial abundance (BA) were studied in sea ice and at the ice–water interface (IWI) in the Western
Canadian Arctic during the spring and summer 2008. CR was converted to BR empirically. BP increased over the season and was
on average 22 times higher in sea ice as compared with the IWI. Rates in ice samples were highly variable ranging from 0.2
to 18.3 μg C l−1 d−1. BR was also higher in ice and on average ~10 times higher than BP but was less variable ranging from 2.39 to 22.5 μg C l−1 d−1. Given the high variability in BP and the relatively more stable rates of BR, BP was the main driver of estimated BGE (r
2 = 0.97, P < 0.0001). We conclude that microbial respiration can consume a significant proportion of primary production in sea ice and
may play an important role in biogenic CO2 fluxes between the sea ice and atmosphere. 相似文献
16.
U. H. Brockmann 《Aquatic Ecology》1994,28(3-4):371-381
In the low salinity region of the Elbe estuary in March–April 1992 the turbidity zone was characterized by high loads of suspended
matter, 7% of which was organic material (750 μM C) at the surface. Particulate nitrogen, phosphorus and carbohydrates concentrations
reached 55 μM N, 10 μM P and more than 15 μM glc. eq., corresponding to 13% of total C, at the surface and increasing threefold
near the bottom.
In spite of the peaking of particulate organic material levels in the maximum turbidity zone, there were only consistent qualitative
changes in total particulate C, N, P, and carbohydrates along the Elbe estuary. Downstream, both the percentage of particulate
organic material and the turbidity: organic material ratio decreased, indicating decomposition in the upper estuary and dilution
with inorganic suspended matter from the lower estuary.
Diatoms, the dominant phytoplankton group, decreased from the upper reaches towards the turbidity zone by 0.3 (surface) and
1.5 mg C l−1 (bottom). This corresponded to 12 and 60% of the decrease in total particulate carbon. Estimated local input of organic carbon
by primary production (21 μg Cl−1d−1) was almost compensated by calculated minimum grazing (14 μg C l−1d−1). Considering net primary production and grazing, the dissimilation by zooplankton (5 μg C l−1d−1) and heterotrophic bacterial decomposition (48 μg C l−1d−1), when summed over the estimated flushing time (12 days) represented a loss of suspended organic matter of 0.6 mg Cl−1. Since this was only 20% of the observed decrease in particulate carbon, significant dilution processes must be assumed.
Dissolved organic nitrogen decreased from 35 to 10 μM N and dissolvd organic phosphorus from 0.6 to 0.1 μM P towards the sea,
mainly due to dilution. The distribution of phosphate, with highest loads in the turbidity maximum of 2.4 μM, suggested an
interaction with the accumulated load of particulate material. 相似文献
17.
Complete degradation of tetrachloroethene by combining anaerobic dechlorinating and aerobic methanotrophic enrichment cultures 总被引:3,自引:0,他引:3
J. Gerritse V. Renard J. C. Gottschal J. Visser 《Applied microbiology and biotechnology》1995,43(5):920-928
Degradation of tetrachloroethene (perchloroethylene, PCE) was investigated by combining the metabolic abilities of anaerobic
bacteria, capable of reductive dechlorination of PCE, with those of aerobic methanotrophic bacteria, capable of co-metabolic
degradation of the less-chlorinated ethenes formed by reductive dechlorination of PCE. Anaerobic communities reductively dechlorinating
PCE, trichloroethene (TCE) and dichloroethenes were enriched from various sources. The maximum rates of dechlorination observed
for various chloroethenes in these batch enrichments were: PCE to TCE (341 μmol l-1 day-1), TCE to cis-dichloroethene (159 μmol l-1 day-1), cis-dichloroethene to chloroethene (99 μmol l-1 day-1) and trans-dichloroethene to chloroethene (22 μmol l-1 day-1). A mixture of these enrichments was inoculated into an anoxic fixed-bed upflow column. In this column PCE was converted
mainly into cis-1, 2-dichloroethene, small amounts of TCE and chloroethene, and chloride. Enrichments of aerobic methanotrophic bacteria
were grown in an oxic fixed-bed downflow column. Less-chlorinated ethenes, formed in the anoxic column, were further metabolized
in this oxic methanotrophic column. On the basis of analysis of chloride production and the disappearance of chlorinated ethenes
it was demonstrated that complete degradation of PCE was possible by combining these two columns. Operation of the two-column
system under various process conditions indicated that the sensitivity of the methanotrophic bacteria to chlorinated intermediates
represented the bottle-neck in the sequential anoxic/oxic degradation process of PCE.
Received: 24 October 1994 / Received revision: 20 January 1995 / Accepted: 23 January 1995 相似文献
18.
Distribution of viruses and their impact on bacterioplankton in mesotrophic and eutrophic reservoirs
Spatial distribution of planktonic viral particles (virioplankton) and mortality of heterotrophic bacteria caused by viral
lysis were studied in the eutrophic Ivan’kovskoe and mesotrophic Uglichskoe reservoirs (the Upper Volga). During the summer
peak of phytoplankton, the number of viral particles was higher in the Ivan’kovskoe Reservoir ((55.1 ± 9.5) × 106 ml−1 on average) than in the Uglichskoe Reservoir ((42.9 ± 5.1) × 106 ml−1 on average). The ratio of viral to bacterial abundances ranged from 2.5 to 7.0. The average number of mature phages in infected
heterotrophic bacteria varied from 17 to 109 particles/cell. Most of the infected bacterial cells in the Ivan’kovskoe Reservoir
were rod-shaped, and, in the Uglichskoe Reservoir, they were mainly vibrio-shaped. In the Ivan’kovskoe Reservoir, from 8.3
to 22.4% of planktonic bacteria were infected by phages, suggesting phage-induced mortality of bacterioplankton equal to 10.5–34.8%
(19.1% on average) of the daily bacterial production. In the Uglichskoe Reservoir, from 9.4 to 33.5% of bacteria were phage-infected,
suggesting phage-induced bacterial mortality of 13.7–40.2% (23.5% on average) of the daily bacterial production. The obtained
results testify to an important role of autochthonous viruses in the regulation of bacterioplankton abundance and production
in the reservoirs. 相似文献
19.
Abstract
The investigation of the bacterial community in the Kühw?rter Wasser, a macrophyte-dominated arm of the River Danube backwater
system near Vienna, revealed that variation in microbial densities and biomass could be related to a characteristic sequence
in morphotype composition over the seasons. Maximal bacterial cell numbers and biomass occured in early summer, with values
of up to 9 × 109 cells l−1 and 122 μg C l−1, respectively, caused by a massive increase of vibrio-shaped cells. On the other hand, in early spring, filamentous bacteria
were responsible for a marked increase in bacterial biomass, making up 40% of the total bacterial biomass. Over the year,
rod-shaped cells were the dominating morphotype, while the biomass of cocci was rather negligible. In winter, cell numbers
and biomass showed minimal values with 2.0 × 109 cells l−1 and 28 μg C l−1, respectively, and bacteria were considered to be substrate and temperature limited during this period. Saturation values
of the incorporation of 3H-thymidine into DNA, for the estimation of bacterial secondary production, varied seasonally, ranging from 5 nm to 40 nm. Thus, saturation experiments needed to be conducted on a regular basis. Also, the amount of labeled thymidine in the DNA,
as a percentage of labeled thymidine in the TCA precipitate, varied over the year. Minimum values of 45% were recorded during
the cold season, while maximum values of 75–80% at the beginning of June coincided with high chlorophyll a values and minimal K
m-values derived from saturation experiments. The potential role of the nitrogen-rich nucleoside thymidine as a readily utilizable
substrate for bacteria during labeling experiments, under varying conditions of substrate availability, is discussed. Bacterial
secondary production rates ranged from 0.3 μg C l−1 h−1 in winter to values of 10 μg C l−1 h−1 in August, where phytoplanktonic biomass reached the summer maximum, and bacterial biomass was calculated to be renewed 3
times per day. An estimation of the bacterial carbon demand showed that for the major part of the year, with the exception
of early spring, the bacterioplankton community in the Kühw?rter Wasser was dependent on carbon sources other than phytoplanktonic
primary production.
Received: 22 March 1996; Revised: 1 August 1996 相似文献
20.
Seasonal variations of phyto-, bacterio- and colourless flagellate plankton were followed across a year in the large shallow Lake Balaton (Hungary). Yearly average chlorophyll-a concentration was 11 µg 1–1, while the corresponding values of bacterioplankton and heterotrophic nanoflagellate (HNF) plankton biomass (fresh weight) were 0.24 mg 1–1 and 0.35 mg 1–1, respectively. About half of planktonic primary production was channelled through bacterioplankton on the yearly basis. However, there was no significant correlation between phytoplankton biomass and bacterial abundance. Bacterial specific growth rates were in the range of 0.009 and 0.09 h–1, and ended to follow the seasonal changes in water temperature. In some periods of the year, predator-prey relationships between the HNF and bacterial abundance were obvious. The estimated HNF grazing on bacteria varied between 3% and 227% of the daily bacterial production. On an annual basis, 87% of bacterial cell production was grazed by HNF plankton. 相似文献