Microbial Dynamics Subject to Metabolic Mass Transfer

2006 ◽  
Author(s):  
Johnathan Vadasz
Keyword(s):  
Mass Transfer ◽  
Cell Growth ◽  
Inflection Point ◽  
Microbial Population ◽  
Essential Feature ◽  
Food Microbiology ◽  
Lag Phase ◽  
Microbial Dynamics ◽  
Resource Dynamics ◽  
Abiotic Resource

Accounting for metabolic mass transfer and abiotic resource dynamics is not common in modeling microbial population growth. In this paper it is demonstrated that the latter is an essential feature that needs to be considered if reliable results are sought. The results of a model that takes the metabolic mass transfer and abiotic resource dynamics into account are shown to capture a variety of features that appear in experiments such as a Lag phase, a Logarithmic Inflection Point, growth followed by decline and oscillations. The results have a wide variety of implications and applications, from food microbiology and wine fermentation, up to human cell growth, where the latter includes tumor growth.

The Impact of Metabolic Mass Transfer and Abiotic Resource Dynamics on Microbial Growth

2003 ◽  
Author(s):  
Johnathan J. Vadasz
Keyword(s):  
Mass Transfer ◽  
Inflection Point ◽  
Microbial Growth ◽  
Microbial Population ◽  
Essential Feature ◽  
Food Microbiology ◽  
Lag Phase ◽  
Resource Dynamics ◽  
Abiotic Resource ◽  
The Impact

Accounting for metabolic mass transfer and abiotic resource dynamics is not common in modeling microbial population growth. In this paper it is demonstrated that the latter is an essential feature that needs to be considered if reliable results are sought. The results of a model that takes the metabolic mass transfer and abiotic resource dynamics into account are shown to capture a variety of features that appear in experiments such as a Lag phase, a Logarithmic Inflection Point, growth followed by decline and oscillations. The results have a wide variety of implications and applications, from food microbiology and wine fermentation, up to human cell growth, where the latter includes tumor growth.

Performance and microbial dynamics in the coarse pore filtration activated sludge process at different SRTs (solids retention times)

2003 ◽  
Vol 47 (12) ◽  
pp. 73-80 ◽  
Author(s):  
M.R. Alavi Moghaddam ◽  
Y. Guan ◽  
H. Satoh ◽  
T. Mino
Keyword(s):  
Microbial Population ◽  
The Other ◽  
Activated Sludge Process ◽  
Filamentous Bacteria ◽  
Microbial Dynamics ◽  
Effluent Quality ◽  
Solids Retention ◽  
Microbial Population Dynamics ◽  
Operation Pressure ◽  
Filter Clogging

In this research, three SRTs (about 10, 30 and 75 days (without wasting the sludge except for sampling)) were applied to three reactors equipped with non-woven and coarse pore filter modules. The flux was adjusted to about 1 m/d during operation. The main objective of the study was to compare the performance and microbial population dynamics under different SRTs in this process. The results of reactors with SRTs of about 10 and 30 days have shown very good effluent quality without any clogging problem for more than 4 months of operation. For the reactor with long SRT (75 days), the filter clogging was observed after about 80 days of operation and caused an increase in the operation pressure and deterioration in effluent quality on some days. Excessive abundance of filamentous bacteria was observed in the reactor with SRT of about 10 days, which had the best effluent quality. According to the FISH results, type 021N was predominant in the reactor with long SRT, which had the clogging problem. On the other hand, other reactors (with SRTs of about 10 and 30 days) did not contain much type 021N, but some other filamentous bacteria dominated. Maximum EPS concentration (as mg/L) was observed in the reactor with long SRT. Also the abundance of two types of metazoa (Pristina sp. and tardigrades) was observed in the reactor with long SRT, which had the clogging problem and poor effluent quality.

Metabolic Mass Transfer Effect in Monotonic and Non-Monotonic Growth of Micro-Organisms

2003 ◽  
Author(s):  
Peter Vadasz ◽  
Alisa S. Vadasz
Keyword(s):  
Mass Transfer ◽  
Growth Theory ◽  
Lag Phase ◽  
Neoclassical Theory ◽  
Mass Transfer Effect ◽  
Future Potential ◽  
Micro Level ◽  
Micro Organisms ◽  
Neoclassical Growth Theory ◽  
Neoclassical Growth

A proposed Neoclassical growth theory of micro-organisms is shown to apply in a much wider variety of cases, from micro-level organisms via animal and human cell growth and up to the macro-level populations encountered in ecology. Including the metabolic mass transfer effects, that are an essential ingredient of the Neoclassical Theory, allows for the recovery of substantial and distinct phenomena observed experimentally. The proposed theory identifies the mechanism controlling the Lag phase, a result that holds impressive future potential in diverse applications. Different theoretical results are presented and compared with experimental data to substantiate the claim that the model based on the Neoclassical Growth Theory is the only available model that produces results, which are consistent with all experimental evidence.

Micro-environments and mass transfer phenomena in biofilms studied with microsensors

1999 ◽  
Vol 39 (7) ◽  
pp. 173-178 ◽  
Author(s):  
Dirk de Beer ◽  
Andreas Schramm
Keyword(s):  
Mass Transfer ◽  
Liquid Flow ◽  
Microbial Population ◽  
In Situ Hybridisation ◽  
Molecular Techniques ◽  
Complex Structures ◽  
Microbial Composition ◽  
Direct Observations ◽  
Direct Measurements

Direct observations on chemical micro-environment and microbial composition in biofilms are rare. The combination of microsensor and molecular techniques is highly useful for studies on the microbial ecology of biofilms. We shortly describe some applications of microsensors to study mass transfer phenomena and microbial processes in biofilms. It has recent been recognized that biofilms are not always flat layers of cells, but can consist of complex structures allowing liquid flow. Thus the classical view, that transport in biofilms is diffusional, is challenged. In laboratory grown biofilms the effect of convection on mass transfer was demonstrated. The microsensor technique has improved, so that direct in situ measurements in living biofilms are possible. By direct measurements of liquid flow with microsensors we show that in biofilms grown in bioreactors heterogeneity and convectional transport must also be taken into account. For the description of the microbial population we use molecular techniques, such as in situ hybridisation with 16S rRNA-targeted oligonucleotide probes. In a nitrifying-denitrifying biofilm we found a complex nitrifying community consisting of members of the genera Nitrosomonas, Nitrosospira, Nitrobacter and Nitrospira. Their occurrence was correlated with nitrification activity as determined by microsensor measurements.

scholarly journals Sediment Facilitates Microbial Degradation of the Herbicides Endothall Monoamine Salt and Endothall Dipotassium Salt in an Aquatic Environment

2018 ◽  
Vol 15 (10) ◽  
pp. 2255
Author(s):  
Md. Shahidul Islam ◽  
Trevor D. Hunt ◽  
Zhiqian Liu ◽  
Kym L. Butler ◽  
Tony M. Dugdale
Keyword(s):  
Aquatic Environment ◽  
Aquatic Macrophytes ◽  
Direct Evidence ◽  
Microbial Population ◽  
Degradation Pathway ◽  
Lag Phase ◽  
Sediment Sources ◽  
Dipotassium Salt ◽  
Water And Sediment ◽  
Submerged Aquatic Macrophytes

Endothall dipotassium salt and monoamine salt are herbicide formulations used for controlling submerged aquatic macrophytes and algae in aquatic ecosystems. Microbial activity is the primary degradation pathway for endothall. To better understand what influences endothall degradation, we conducted a mesocosm experiment to (1) evaluate the effects of different water and sediment sources on degradation, and (2) determine if degradation was faster in the presence of a microbial community previously exposed to endothall. Endothall residues were determined with LC-MS at intervals to 21 days after endothall application. Two endothall isomers were detected. Isomer-1 was abundant in both endothall formulations, while isomer-2 was only abundant in the monoamine endothall formulation and was more persistent. Degradation did not occur in the absence of sediment. In the presence of sediment, degradation of isomer-1 began after a lag phase of 5–11 days and was almost complete by 14 days. Onset of degradation occurred 2–4 days sooner when the microbial population was previously exposed to endothall. We provide direct evidence that the presence and characteristics of sediment are of key importance in the degradation of endothall in an aquatic environment, and that monoamine endothall has two separate isomers that have different degradation characteristics.

scholarly journals Autocrine interleukin-1 beta regulates both proliferation and apoptosis in EL4-6.1 thymoma cells

Blood ◽  
1995 ◽  
Vol 85 (12) ◽  
pp. 3532-3537 ◽  
Author(s):  
M Fratelli ◽  
V Gagliardini ◽  
G Galli ◽  
P Gnocchi ◽  
P Ghiara ◽  
...  
Keyword(s):  
Cell Growth ◽  
Interleukin 1 ◽  
Exponential Phase ◽  
Lag Phase ◽  
Interleukin 1 Beta ◽  
Plateau Phase ◽  
Cell Type ◽  
Regulatory Factor ◽  
Proliferation And Apoptosis ◽  
Single Cell Type

We demonstrate here that EL4–6.1 cells, a mouse thymoma that expresses high levels of membrane interleukin (IL)-1 receptors, produce IL-1 beta as an autocrine regulatory factor. Endogenous IL-1 beta sustains both proliferation and apoptosis: during the exponential phase, it mainly promotes proliferation, while during the plateau phase of cell growth, it induces death by apoptosis. Additionally, we show that exogenous IL-1 beta added to EL4–6.1 cells in lag phase induces apoptosis in a portion of the cells and proliferation in the remaining cells. Therefore, IL-1 beta can exert two completely opposite effects on a single cell type, depending on the state of the target cell.

Nonlinear Dynamics of Brewing Yeast Cell Growth in Alginate Micro-Beads

2006 ◽  
Vol 518 ◽  
pp. 519-524 ◽  
Author(s):  
Iva Pajić-Lijaković ◽  
V. Nedović ◽  
B. Bugarski
Keyword(s):  
Nonlinear Dynamics ◽  
Mass Transfer ◽  
Cell Growth ◽  
Yeast Cell ◽  
Cell Concentration ◽  
Brewing Yeast ◽  
Final Cell Concentration ◽  
Alginate Matrices ◽  
Optimal Diameter ◽  
Cell Leakage

The nonlinear dynamics of brewing yeast cell growth in porous Ca-alginate matrices is considered experimentally and theoretically. The applications of alginate matrices include the reduction of internal mass transfer resistance, minimized cell leakage and growth restriction due to interactions between matrices and cell membranes comparatively to free cell culture conditions. The effects of micro-bead diameters in the range 0.3-2.0 mm on yeast cell growth were investigated. The stochastic mathematical model from the Langevin class is proposed for the interpretation of cell growth, affected by four micro-processes: micro-environmental quality changes due to nutrient diffusion into the micro-beads, cell leakage, repulsive interactions between boundary layers around the cells themselves, which contribute to the dynamics of cell growth as a negative, nonlinear feedback restriction and random kinetics effects. Such a model is used for the prediction of the optimal diameter of micro-beads, which ensures maximal final cell concentration. The results of cell growth in alginate matrices study have indicated an optimal diameter of 0.5-0.6 mm for micro-beads. Immobilized cells in these beads were not restricted significantly by mass transfer of nutrients and by cell leakage. The highest final cell concentration value indicated the largest feed-back restriction quantified by the constitutive parameter b.

scholarly journals Sediment Facilitates Microbial Degradation of The Herbicides Endothall Monoamine Salt and Endothall Dipotassium Salt in an Aquatic Environment

2018 ◽  
Author(s):  
Md. Shahidul Islam ◽  
Trevor D Hunt ◽  
Zhiqian Liu ◽  
Kym L Butler ◽  
Tony M Dugdale
Keyword(s):  
Aquatic Environment ◽  
Aquatic Macrophytes ◽  
Direct Evidence ◽  
Microbial Population ◽  
Degradation Pathway ◽  
Lag Phase ◽  
Sediment Sources ◽  
Dipotassium Salt ◽  
Water And Sediment ◽  
Submerged Aquatic Macrophytes

Endothall dipotassium salt and monoamine salt are herbicide formulations used for controlling submerged aquatic macrophytes and algae in aquatic ecosystems. Microbial activity is the primary degradation pathway for endothall. To better understand what influences endothall degradation, we conducted a mesocosm experiment to 1) evaluate the effects of different water and sediment sources on degradation, and 2) determine if degradation was faster in the presence of a microbial community previously exposed to endothall. Endothall residues were determined with LC-MS at intervals to 21 days after endothall application. Two endothall isomers were detected. Isomer-1 was abundant in both endothall formulations, while isomer-2 was only abundant in the monoamine endothall formulation and was more persistent. Degradation did not occur in the absence of sediment. In the presence of sediment degradation if isomer-1 began after a lag phase of 5-11 days and was almost complete by 14 days. Onset of degradation occurred 2-4 days sooner when the microbial population was previously exposed to endothall. We provide direct evidence that the presence and characteristics of sediment are of key importance in the degradation of endothall in an aquatic environment, and that monoamine endothall has two separate isomers that have different degradation characteristics.

Sign in / Sign up

Export Citation Format

Share Document