Search

The mathematical modelling equations are developed to combine the mathematical model for a Pseudo – Gaussian distribution curve – for Growth of Covid19 . The superimposition of Gaussiun curve with Microbial growth curve can be fitted for the resulant model equation considering the sharp Exponential spreading of the Virus .https://data.mendeley.com/datasets/5cbs2c35ps/draft?a=5a5c488e-cd86-457c-8504-ea332132134f . Datta, Jaydip (2020), “Covid19 – A Mathematical modelling of a PSEUDO-GAUSSIUN Contour”, Mendeley Data, V3, doi: 10.17632/5cbs2c35ps.3

Summary During the implementation of a microbial-enhanced-oil-recovery (EOR) (MEOR) technique in a sandstone formation, various reservoir physicochemical, microbial kinetic, and operational parameters play major roles in governing the efficiency of crude-oil recovery from a hydrocarbon reservoir. The present study numerically investigates the sensitivity of sandstone formation effective porosity; different injected strains of the species Bacillus under optimal metabolic conditions and possessing distinct values of maximum microbial-specific-growth rate, Monod saturation constant, and yield coefficient; and crucial operational parameters on biomass and biosurfactant production and their effects on microscopic oil-displacement efficiency within the sandstone reservoir, along with prompting modifications in rock physicochemical properties. A black-oil biochemical multispecies reactive transport model in porous sandstone media is developed by coupling the kinetic model with the corresponding transport model involving microbial sorption. The governing equations involve coupled transport of nutrients and microbes by dispersion and convection, growth and decay rates of microbes, chemotaxis, nutrient consumption, and deposition of microbes and nutrients on rock-grain surfaces caused by reversible/irreversible sorption. Coupled empirical equations are used to estimate biosurfactant production, oil/water-interfacial-tension (IFT) reduction, change in the viscosity of injection fluid, and their effects on oil relative permeability and mobility, and thus a decrease in residual oil saturation within the reservoir. The finite-difference-discretization technique is adopted to solve the governing equations. Results of the present model are found to be numerically stable and match very well, when verified, with the previously published analytical, numerical, and experimental results. The model results suggest that at very low reservoir porosity (approximately 10%), an early breakthrough of nutrients, microbes, and biosurfactant leave insignificant concentrations in their respective fronts, which are insufficient for the recovery of the trapped oil. Also, increase in porosity to approximately 30% and beyond causes loss of nutrients, microbes, and biosurfactant because they undergo higher dispersion during their transport within the reservoir. Thus, sandstone formations possessing an intermediate effective porosity value of approximately 20% significantly enhance the efficiency of the overall MEOR process. Further, it is observed that the nature of microbes and nutrients used for MEOR application affect biosurfactant production, and in turn oil recovery, to a large extent. Those microbial species with far lower Monod-saturation-constant values have high affinity toward their substrates. This phenomenon dramatically increases the rates of nutrient consumption and production of biomass and biosurfactant within a reservoir when suitable substrate compounds are used, irrespective of differences in the yield coefficients of the microbes. Further MEOR simulation studies within a sandstone core exhibited maximum oil displacement and recovery at a run time of 5 hours, injected-microbial concentration of 4.32×10–3 mg/cm3, and maximum specific growth rate of 0.35 hours–1. Bioplugging-induced formation damage negatively affecting the oil-recovery efficiency is also observed with an increase in the process run time. The screened microbe also exhibited the possibility of wettability alteration of sandstone-formation rock from mixed/oil-wet to water-wet. Thus, the present study provides an improved understanding of the combined effects of reservoir porosity, microbial kinetic, and key operational parameters on fundamental MEOR processes, which will better characterize and develop an effective strategy to determine the suitability of an MEOR technique in a typical sandstone reservoir. Moreover, the developed numerical model is easier to implement and produces faster results with relatively lower computational cost, which helps in making a quick decision before applying MEOR processes in the field.

A conversion of the global terrestrial carbon sink to a source is critically dependent on the microbially mediated decomposition of soil organic matter (SOM). We have developed a detailed, process-based, mechanistic model for simulating SOM decomposition and its associated processes, based on Microbial Kinetics and Thermodynamics, called the MKT model. We formulated the sequential oxidation-reduction potential (ORP) and chemical reactions undergoing at the soil-water zone using dual Michaelis-Menten kinetics. Soil environmental variables, as required in the MKT model, are simulated using one of the most widely used watershed-scale models - the soil water assessment tool (SWAT). The MKT model was calibrated and validated using field-scale data of soil temperature, soil moisture, and N2O emissions from three locations in the province of Saskatchewan, Canada. The model evaluation statistics show good performance of the MKT model for daily soil N2O simulations. The results show that the proposed MKT model can perform better than the more widely used process-based and SWAT-based models for soil N2O simulations. This is because the multiple processes of microbial activities and environmental constraints, which govern the availability of substrates to enzymes were explicitly represented. Most importantly, the MKT model represents a step forward from conceptual carbon pools at varying rates.

Over the past decades great attention has been paid to the phenomenon of microorganisms’ ability to transfer electrons between their metabolism and solid conductive surfaces. This fact keeps potential to gain extensive reliance for applications including electricity production coupled to wastewater treatment, bioremediation, and synthesis of value products. Effective electrochemical communication directly or via various mediated systems between microorganisms and electrodes is a challenge of fundamental interdisciplinary research. The present review discusses the main critical factors affecting efficient electrochemical “wiring” living cells to conductive electrode surfaces, including the molecular mechanism that makes electron exchange possible for various microorganisms, utilization of different types of mediators and new electrode materials to enhance microbial kinetics as opposed to other bioelectrochemical systems based on purified enzymes 1. , 2. .

Three pilot-scale bioreactors were started up and operated under salinity-amended urban wastewater feeding. The bioreactors were configured as membrane bioreactor and two different hybrid, moving bed biofilm reactor-membrane bioreactor and operated with a hydraulic retention time of 9.5 h, a solid residence time of 11.75 days and a total solids concentration of 2500 mg L-1 . The three systems showed excellent performance in suspended solids, BOD5 , and COD removal (values of 96-100%, 97-99%, and 88-90%, respectively), but poor nitrogen removal (values of 20-30%). The bacterial community structure during the start-up phase and the stabilization phase were different, as showed by β-diversity analyses. The differences between aerobic and anoxic biomass-and between suspended and attached biomass-were higher at the start-up phase than at the stabilization phase. The start-up phase showed high abundances of Chiayiivirga (mean values around 3-12% relative abundance) and Luteimonas (5-8%), but in the stabilization phase, the domination belonged to Thermomonas (3-14%), Nitrobacter (3-7%), Ottowia (3-11.5%), and Comamonas (2-6%), among others. Multivariate redundancy analyses showed that Thermomonas and Nitrosomonas were positively correlated with fast autotrophic kinetics, while Caulobacter and Ottowia were positively correlated with fast heterotrophic kinetics. Nitrobacter, Rhodanobacter, and Comamonas were positively correlated with fast autotrophic and heterotrophic kinetics. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1483-1495, 2017.

The discovery that approximately 20% of natural gas is microbial in origin has elevated interest in microbially enhanced coalbed methane (MECoM). However, a rational approach to exploit this calls for the development of reservoir scale models that include the effect of microbial activity. To address this, we have developed a multiscale, multiphase, multicomponent reactive-transport model for the production of microbially enhanced coalbed methane (MECoM) that includes microbial kinetics. The model is used to evaluate field scale strategies for commercial MECoM production. Optimization studies are also conducted over a range of compositions of the injected nutrient and injector bottomhole pressures. In order to account for the effect of uncertainty in the model parameters, mean-variance robust optimization is performed, allowing a trade-off between performance and robustness. Proxy modeling is performed in a multivariate polynomial chaos expansion framework to evaluate the cost functions involved in the robust optimization and sparse expansions are constructed in order to deal with issues related to high dimensionality. The optimization strategy is tested for different trade-offs between robustness and performance. It is observed that for the given case, the location of robust optimal points does not vary unless only robustness is included in the objective function, and nominal performance is not.

Activated sludge processes with an ultra-short sludge retention time (ultra-short-SRT) are considered to have potential for energy and resource recovery from wastewater. The present study focused on the sludge characteristics, system performance and microbial kinetics in ultra-short-SRT activated sludge (USSAS) processes using typical domestic wastewater (SRT = 0.5, 1, 2, 3 and 4 d). The results showed that compared with the sludge in conventional activated sludge (CAS) processes, the sludge structure in USSAS system was looser (fractal dimension, D2P, 1.19–1.33), the boundary was rougher (pore boundary fractal dimension, DB, 1.44–1.59), the sludge concentration was lower, and the sludge volume index (SVI) was higher; bacteria such as Thiothrix and Trichococcus that cause sludge bulking, which poses an operation risk, were extensively detected, especially at SRTs of 0.5 d and 1.0 d. The performance in terms of total chemical oxygen demand (tCOD) and phosphorus removal increased with increasing SRT, and the highest removal rate (approximately 85% for tCOD and 90% for phosphorus) was observed when the SRT was 4 d. Both bioconversion and biosorption were responsible for the C/P separation, and their roles were different for different types of organic matter and phosphorus under different SRT conditions. The proportion of phosphate-accumulating organisms (PAO) reached 2.4% when the SRT was 3 d, resulting in highly effective biological phosphorus removal. The values of microbial kinetic parameters such as YH and KdH in USSAS systems were higher than those in CAS systems, indicating faster microbial community renewal. This study was helpful for understanding the characteristics of USSAS process.

International audience; Dew retting of fiber crops, such as hemp or flax, in the field after harvest promotes the microbial biodegradation of the tissues surrounding cellulosic fibers, which helps preserve the quality of fibers during their extraction and valorization for industry. This bioprocess is currently the bottleneck for plant fiber valorization because it is empirically managed and its controlling factors have not been properly quantified. A novel multiscale model representing tissue and polymer biodegradation was developed to simulate microbial growth on the stem during retting. The model was evaluated against experimental hemp retting data. It consistently simulated the mass loss of eight plant polymers belonging to two tissues of the stem outer layer, i.e., parenchyma and fiber bundles. Microbial growth was modeled by Monod equations and modulated by the functions of temperature and moisture. This work provides a tool for gaining more insights into microorganism behavior during retting under local climate conditions.

The article summarizes basic principles, methods, and the most essential results of kinetic studies in microbiology relevant to biotechnology. Microbial kinetics are based on experimental studies of all dynamic manifestations of microbial life (growth, survival, death, product formation, mutations, cell cycles, and environmental effects) and analysis of underlying mechanisms using mathematical models. The article introduces various kinetic models used to describe microbial growth dynamics starting from simple exponential equations and empirical logistic equations to Monod models, its modifications, and to more complex structured models simulating cellular metabolic network. Now equally useful should be considered genome-based flux-balance models and simplified dynamic models giving an aggregated view of microbial metabolism and successfully simulating a diverse range of observed growth patterns. The second part of the article reviews various factors affecting microbial growth, including nature of nutrient substrates, environmental factors (pH and temperature), inhibitory products, mutations, and autoselection in continuous culture. We discuss also the problem of the quantitative description of growth and product formation dynamics. Two contrasting examples are given: (1) production of secondary metabolites, such as antibiotics, and (2) formation of intermediary fermentation products under aerobic conditions (Crabtree effect).

pH influences the occurrence and distribution of microorganisms. Microbes typically live over a range of 3 to 4 pH units and are described as acidophiles, neutrophiles, and alkaliphiles, depending on the optimal pH for growth. Their growth rates vary with pH along bell- or triangle-shaped curve, which reflects pH limits of cell structure integrity and the interference of pH with cell metabolism. We propose that pH can also affect the thermodynamics and kinetics of microbial respiration, which then help shape the composition and function of microbial communities. Here we use geochemical reaction modeling to examine how environmental pH controls the energy yields of common redox reactions in anoxic environments, including syntrophic oxidation, iron reduction, sulfate reduction, and methanogenesis. The results reveal that environmental pH changes the energy yields both directly and indirectly. The direct change applies to the reactions that consume or produce protons whereas the indirect effect, which applies to all redox reactions, comes from the regulation of chemical speciation by pH. The results also show that the energy yields respond strongly to pH variation, which may modulate microbial interactions and help give rise to the pH limits of microbial metabolisms. These results underscore the importance of pH as a control on microbial metabolisms and provide insight into potential impacts of pH variation on the composition and activity of microbial communities. In a companion paper, we continue to explore how the kinetics of microbial metabolisms responds to pH variations, and how these responses control the outcome of microbial interactions, including the activity and membership of microbial consortia.

Dysmenorrhea painful menstruation is a common chronic condition of pain that affects young women decrease their ability to function at a percent and ultimately causing a reduction in productively for the affected person for a period of time Many studies have shown that the level of knowledge about dysmenorrhea is unclear especially in young women and that it indeed has the ability to disrupt a peaceful flow in rhythm and pattern of women in executing daily activities The aim of this study is to determine the true extent at which dysmenorrhea interferes with daily activities

Numerically simulated heat transfer model of frozen US military rations was combined with microbial kinetics to predict the microbial spoilage of the food products, during two possible temperature abuse scenarios. An army breakfast menu box containing five different food items was selected for conducting this research. One of the food item in the menu box, beefsteak, was chosen for detailed microbial study. A microbial predictive tool was used to identify and evaluate the kinetics of the most prone microorganism that can grow in a beefsteak. Numerical predictions suggested that the food items exposed to external temperatures ranging from 20 °C to 40 °C can be allowed to stay at those temperatures for maximum times of 28.7 h to 11.9 h, respectively. The food items can be allowed to stay inside the broken freezer for a maximum time of 186 h, to ensure microbial safety in the case of freezer failure.

WOS: 000448383600019, The gas generated by anaerobic fermentation of organic wastes is called biogas. Since it contains methane, it can be burnt and so it can be used as an alternative energy source. The production of biogas is an anaerobic treatment process, it is important to understand the basic biochemistry and microbiology of anaerobic systems. This study demonstrates the kinetic study to find out the best microbial kinetics which will be necessary for the design of an anaerobic fermenter. For this purpose, chicken manure and chicken manure with inoculation culture were used. Experiments were operated under mesophilic conditions in laboratory type glass fermenters each having a volume of ten liters., European CommunityEuropean Community (EC), This study was held at Ege University, Chemical Engineering Department, Izmir-Turkey. This project, Fermented Product As A Hygienic Fertilizer And Soil Improver"was supported by European Community.

La enfermedad de Chagas es un problema para la salud publica mundial, sobre todo en paises de America Latina donde la enfermedad es endemica. En el estado de Guerrero, Mexico, las caracteristicas geografi cas, ecologicas y ambientales han favorecido la presencia del vector transmisor de la enfermedad. Las estrategias preventivas relacionadas con las viviendas, donde se puede encontrar al vector, se han realizado mediante control quimico, que contamina y afecta la salud de la poblacion

Scale-up of bioprocesses is hampered by open questions, mostly related to poor mixing and mass transfer limitations. Concentration gradients of substrate, carbon dioxide, and oxygen in time and space, especially in large-scale high-cell density fed-batch processes, are likely induced as the mixing time of the fermentor is usually longer than the relevant cellular reaction time. Cells in the fermentor are therefore repeatedly exposed to dynamic environments or perturbations. As a consequence, the heterogeneity in industrial practices often decreases either yield, titer, or productivity, or combinations thereof and increases by-product formation as compared to well-mixed small-scale bioreactors, which is summarized as scale-up effects. Identification of response mechanisms of the microorganism to various external perturbations is of great importance for pinpointing metabolic bottlenecks and targets for metabolic engineering. In this review, pulse response experimentation is proposed as an ideal way of obtaining kinetic information in combination with scale-down approaches for in-depth understanding of dynamic response mechanisms. As an emerging tool, computational fluid dynamics is able to draw a holistic picture of the fluid flow and concentration fields in the fermentor and finds its use in the optimization of fermentor design and process strategy. In the future, directed strain improvement and fermentor redesign are expected to largely depend on models, in which both microbial kinetics and fluid dynamics are thoroughly integrated.