Phosphate Uptake by Microorganisms in Lake Water: Deviations from Simple Michaelis–Menten Kinetics

1986 ◽  
Vol 43 (2) ◽  
pp. 319-328 ◽  
Author(s):  
Stephen J. Tarapchak ◽  
Lynn R. Herche
Keyword(s):  
Lake Michigan ◽  
Simulation Analysis ◽  
Phosphate Uptake ◽  
Laboratory Culture ◽  
Microbial Populations ◽  
Culture Studies ◽  
Equation Analysis ◽  
Uptake Rates ◽  
Order Of Magnitude ◽  
Substrate Concentrations

Orthophosphate (31Pi) uptake rates by natural Lake Michigan microbial assemblages were measured to test a hypothesis that the instantaneous velocity of 31Pi uptake at low added substrate concentrations is higher than predicted by the simple Michaelis–Menten equation. Analysis of data from most experiments verified this prediction: 31Pi turnover times (Tcalc) obtained by back-extrapolating from "low" substrate regions in Woolf plots ranged from 25% to nearly 3000% of those calculated from "high" substrate regions. Simulation analysis demonstrated that deviations in Tcalc could be at least an order of magnitude higher than previously predicted. Large (>1000%) discrepancies from the simple Michaelis–Menten equation could be caused by "skewed" or "clumped" distributions, where the range in both species half-saturation constants (Kt) and relative abundances is very wide and species with the lowest Kt values are most abundant. A comparison of Kt values for mixed microbial assemblages in Lake Michigan (0.16–19.4 μg P∙L−1) with those from laboratory culture studies (11–364 μg P∙L−1) demonstrates that natural microbial populations have adapted to P-limited environments by synthesizing uptake systems that have Kt values at least an order of magnitude below those detected in culture studies.

scholarly journals Field-obtained carbon and nitrogen uptake rates of phytoplankton in the Laptev and East Siberian seas

2017 ◽  
Author(s):  
Sang Heon Lee ◽  
Jang Han Lee ◽  
Howon Lee ◽  
Jae Joong Kang ◽  
Jae Hyung Lee ◽  
...  
Keyword(s):  
Primary Production ◽  
Arctic Ocean ◽  
Nitrogen Uptake ◽  
The Arctic ◽  
Chl A ◽  
Carbon And Nitrogen ◽  
Uptake Rates ◽  
Order Of Magnitude ◽  
Western Arctic ◽  
System Program

Abstract. The Laptev and East Siberian seas are the least biologically studied region in the Arctic Ocean, although they are highly dynamic in terms of active processing of organic matter impacting the transport to the deep Arctic Ocean. Field-measured carbon and nitrogen uptake rates of phytoplankton were conducted in the Laptev and East Siberian seas as part of the NABOS (Nansen and Amundsen Basins Observational System) program. Major inorganic nutrients were mostly depleted at 100–50 % light depths but were not depleted within the euphotic depths in the Laptev and East Siberian seas. The water column-integrated chl-a concentration in this study was significantly higher than that in the western Arctic Ocean (t-test, p > 0.01). Unexpectedly, the daily carbon and nitrogen uptake rates in this study (average ± S.D. = 110.3 ± 88.3 mg C m−2 d−1 and 37.0 ± 25.8 mg N m−2 d−1, respectively) are within previously reported ranges. Surprisingly, the annual primary production (13.2 g C m−2) measured in the field during the vegetative season is approximately one order of magnitude lower than the primary production reported from a satellite–based estimation. Further validation using field-measured observations is necessary for a better projection of the ecosystem in the Laptev and East Siberian seas responding to ongoing climate change.

scholarly journals Degradation of Starch–Poly(β-Hydroxybutyrate-Co-β-Hydroxyvalerate) Bioplastic in Tropical Coastal Waters

1999 ◽  
Vol 65 (2) ◽  
pp. 431-437 ◽  
Author(s):  
S. H. Imam ◽  
S. H. Gordon ◽  
R. L. Shogren ◽  
T. R. Tosteson ◽  
N. S. Govind ◽  
...  
Keyword(s):  
Weight Loss ◽  
Coastal Waters ◽  
The Other ◽  
Microbial Populations ◽  
Starch Granules ◽  
Ocean Water ◽  
Degradation Rates ◽  
Order Of Magnitude ◽  
Lag Period ◽  
Microbial Enumeration

ABSTRACT Extruded bioplastic was prepared from cornstarch or poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV) or blends of cornstarch and PHBV. The blended formulations contained 30 or 50% starch in the presence or absence of polyethylene oxide (PEO), which enhances adherence of starch granules to PHBV. Degradation of these formulations was monitored for 1 year at four stations in coastal water southwest of Puerto Rico. Two stations were within a mangrove stand. The other two were offshore; one of these stations was on a shallow shoulder of a reef, and the other was at a location in deeper water. Microbial enumeration at the four stations revealed considerable flux in the populations over the course of the year. However, in general, the overall population densities were 1 order of magnitude less at the deeper-water station than at the other stations. Starch degraders were 10- to 50-fold more prevalent than PHBV degraders at all of the stations. Accordingly, degradation of the bioplastic, as determined by weight loss and deterioration of tensile properties, correlated with the amount of starch present (100% starch >50% starch > 30% starch > 100% PHBV). Incorporation of PEO into blends slightly retarded the rate of degradation. The rate of loss of starch from the 100% starch samples was about 2%/day, while the rate of loss of PHBV from the 100% PHBV samples was about 0.1%/day. Biphasic weight loss was observed for the starch-PHBV blends at all of the stations. A predictive mathematical model for loss of individual polymers from a 30% starch–70% PHBV formulation was developed and experimentally validated. The model showed that PHBV degradation was delayed 50 days until more than 80% of the starch was consumed and predicted that starch and PHBV in the blend had half-lives of 19 and 158 days, respectively. Consistent with the relatively low microbial populations, bioplastic degradation at the deeper-water station exhibited an initial lag period, after which degradation rates comparable to the degradation rates at the other stations were observed. Presumably, significant biodegradation occurred only after colonization of the plastic, a parameter that was dependent on the resident microbial populations. Therefore, it can be reasonably inferred that extended degradation lags would occur in open ocean water where microbes are sparse.

scholarly journals Activity assessment of microalgal-bacterial consortia based on respirometric tests

2018 ◽  
Vol 78 (1) ◽  
pp. 207-215 ◽  
Author(s):  
S. Rossi ◽  
M. Bellucci ◽  
F. Marazzi ◽  
V. Mezzanotte ◽  
E. Ficara
Keyword(s):  
Liquid Fraction ◽  
Environmental Parameters ◽  
Nitrifying Bacteria ◽  
Microbial Populations ◽  
Bacterial Consortia ◽  
Black Water ◽  
Activity Assessment ◽  
Uptake Rates ◽  
Biogas Plants ◽  
Activated Sludge Processes

Abstract Respirometric techniques are useful tools to evaluate bacterial activities in activated sludge processes due to their fast execution and the possibility to obtain several kinetic parameters from a single test. Using such techniques in microalgae-bacteria consortia treating wastewater could allow a better understanding of mutual interactions between the microbial populations as a function of environmental parameters. This work aims at developing and testing a novel experimental respirometric protocol to determine oxygen uptake rates and oxygen production rates by a microalgae-bacteria consortium. The defined protocol is characterized by alternating light/dark regimes and by dosing substrates/inhibitors to selectively activate/inactivate microalgal and bacterial metabolisms. The protocol was then applied on microalgal and bacterial consortia, which were grown on the liquid fraction of black water from biogas plants fed on agricultural and municipal waste sludge. Results elucidate the presence and activity of microalgae and nitrifying bacteria in the tested systems, suggesting that the respirometric tests could be included into monitoring procedures of photobioreactors/algal ponds.

Density Estimates of Mysis relicta in Lake Michigan

1979 ◽  
Vol 36 (6) ◽  
pp. 694-698 ◽  
Author(s):  
Nevin E. Grossnickle ◽  
Mark D. Morgan
Keyword(s):  
Key Words ◽  
Lake Michigan ◽  
Density Estimates ◽  
Mysis Relicta ◽  
Deep Station ◽  
Late Instar ◽  
Order Of Magnitude

Density estimates of Mysis relicta based on night vertical net tows at stations of 30–50 m in Lake Michigan were about an order of magnitude larger than previous estimates based on sled tows. Significantly greater density estimates were obtained in night vertical net tows than those collected before sunset at these shallow stations. However, density estimates based on sled tows during daylight were not significantly different from those based on night vertical net tows at a 115-m station in Lake Michigan. At this deep station, a substantially larger percentage of late instar mysids was collected in sled tows than in night vertical net tows. Key words: Mysis relicta, Lake Michigan, density estimates, vertical net tows, epibenthic sled tows

scholarly journals Targeted and Highly Multiplexed Detection of Microorganisms by Employing an Ensemble of Molecular Probes

2014 ◽  
Vol 80 (14) ◽  
pp. 4153-4161 ◽  
Author(s):  
Weihong Xu ◽  
Sujatha Krishnakumar ◽  
Molly Miranda ◽  
Michael A. Jensen ◽  
Marilyn Fukushima ◽  
...  
Keyword(s):  
Abundant Species ◽  
Laboratory Culture ◽  
Molecular Probes ◽  
Molecular Probe ◽  
Clinical Samples ◽  
Culture Independent ◽  
Order Of Magnitude ◽  
Life On Earth ◽  
Probe Set ◽  
Selection Of

ABSTRACTThe vast majority of microscopic life on earth consists of microbes that do not grow in laboratory culture. To profile the microbial diversity in environmental and clinical samples, we have devised and employed molecular probe technology, which detects and identifies bacteria that do and do not grow in culture. The only requirement is a short sequence of contiguous bases (currently 60 bases) unique to the genome of the organism of interest. The procedure is relatively fast, inexpensive, customizable, robust, and culture independent and uses commercially available reagents and instruments. In this communication, we report improving the specificity of the molecular probes substantially and increasing the complexity of the molecular probe set by over an order of magnitude (>1,200 probes) and introduce a new final readout method based upon Illumina sequencing. In addition, we employed molecular probes to identify the bacteria from vaginal swabs and demonstrate how a deliberate selection of molecular probes can identify less abundant bacteria even in the presence of much more abundant species.

Phosphate Removal in a Biofilm Reactor

1991 ◽  
Vol 23 (7-9) ◽  
pp. 1405-1415 ◽  
Author(s):  
Simón González-Martinez ◽  
Peter A. Wilderer
Keyword(s):  
Sequencing Batch Reactor ◽  
Phosphate Uptake ◽  
Early Stage ◽  
Batch Reactor ◽  
Fixed Bed ◽  
Dry Weight ◽  
Biofilm Reactor ◽  
Phosphate Removal ◽  
Organic Substrates ◽  
Uptake Rates

Biological phosphate removal was achieved in a laboratory scale fixed bed biofilm reactor. To create the conditions required to enrich for phosphate accumulating bacteria, the reactor was periodically filled and drained, and the aerator periodically turned on and off (Sequencing Batch Reactor strategy). The reactor performed very effectively, but it took several weeks to reach steady-state. The highest phosphate uptake rates were observed when sequestration of the organic substrates was accomplished at an early stage of the anaerobic process phase, and release of phosphate at the expense of sequestered or stored substrates (endogenous phosphate release) was encouraged. In the range between 15°C to 25°C, the temperature had only minor effects. The biofilm dry weight contained about 5 per cent phosphate.

Phosphate uptake in rat skeletal muscle is reduced during isometric contractions

2004 ◽  
Vol 97 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Kirk A. Abraham ◽  
Ronald L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Inorganic Phosphate ◽  
Phosphate Uptake ◽  
Specific Activity ◽  
Fiber Type ◽  
Rat Skeletal Muscle ◽  
Energy Expenditures ◽  
Contraction Duration ◽  
Uptake Rates ◽  
White Gastrocnemius

During contractions, there is a net efflux of phosphate from skeletal muscle, likely because of an elevated intracellular inorganic phosphate (Pi) concentration. Over time, contracting muscle could incur a substantial phosphate deficit unless Pi uptake rates were increased during contractions. We used the perfused rat hindquarter preparation to assess [32P]Pi uptake rates in muscles at rest or over a range of energy expenditures during contractions at 0.5, 3, or 5 Hz for 30 min. Pi uptake rates were reduced during contractions in a pattern that was dependent on contraction frequency and fiber type. In soleus and red gastrocnemius, [32P]Pi uptake rates declined by ∼25% at 0.5 Hz and 50–60% at 3 and 5 Hz. Uptake rates in white gastrocnemius decreased by 65–75% at all three stimulation frequencies. These reductions in Pi uptake are not likely confounded by changes in precursor [32P]Pi specific activity in the interstitium. In soleus and red gastrocnemius, declines in Pi uptake rates were related to energy expenditure over the contraction duration. These data imply that Pi uptake in skeletal muscle is acutely modulated during contractions and that decreases in Pi uptake rates, in combination with expected increases in Pi efflux, exacerbate the net loss of phosphate from the cell. Enhanced uptake of Pi must subsequently occur because skeletal muscle typically maintains a relatively constant total phosphate pool.

Measuring biomass specific ammonium, nitrite and phosphate uptake rates in aerobic granular sludge

Chemosphere ◽  
2012 ◽  
Vol 89 (10) ◽  
pp. 1161-1168 ◽  
Author(s):  
J.P. Bassin ◽  
R. Kleerebezem ◽  
M. Dezotti ◽  
M.C.M. van Loosdrecht
Keyword(s):  
Phosphate Uptake ◽  
Granular Sludge ◽  
Aerobic Granular Sludge ◽  
Uptake Rates

scholarly journals Revisiting australian ectocarpus subulatus (phaeophyceae) from the hopkins river: distribution, abiotic environment, and associated microbiota

2019 ◽  
Author(s):  
Simon M. Dittami ◽  
Akira F. Peters ◽  
John West ◽  
Thierry Cariou ◽  
Hetty KleinJan ◽  
...  
Keyword(s):  
Brown Algae ◽  
Laboratory Culture ◽  
Bacterial Strains ◽  
Abiotic Environment ◽  
Low Salinity ◽  
Order Of Magnitude ◽  
Original Laboratory ◽  
Surrounding Areas

AbstractEctocarpus is a genus of common marine brown algae. In 1995 a strain of Ectocarpus was isolated from Hopkins River Falls, Victoria, Australia, constituting one of few available freshwater or nearly freshwater brown algae, and the only one belonging to Ectocarpus. It has since been used as a model to study acclimation and adaptation to low salinities and the role of its microbiota in these processes. However, little is known about the distribution of this strain or whether it represents a stable population. Furthermore, its microbiota may have been impacted by the long period of cultivation.Twenty-two years after the original finding we searched for Ectocarpus in the Hopkins River and surrounding areas. We found individuals with ITS and cox1 sequences identical to the original isolate at three sites upstream of Hopkins River Falls, but none at the original isolation site. The osmolarity of the water at these sites ranged from 74-170 mOsmol, and it was rich in sulfate. The diversity of bacteria associated with the algae in situ was approximately one order of magnitude higher than in previous studies of the original laboratory culture, and 95 alga-associated bacterial strains were isolated from E. subulatus filaments on site. In particular, Planctomycetes were abundant in situ but rare in the laboratory-cultured strain.Our results confirm that E. subulatus has stably colonized the Hopkins River, and the newly isolated algal and bacterial strains offer new possibilities to study the adaptation of Ectocarpus to low salinity and its interactions with its microbiome.

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