scholarly journals Investigation of a new effective bacterium for cellulosic degradation

2021 ◽  
Author(s):  
Weining Lin
Keyword(s):  
Growth Rate ◽  
Mathematical Models ◽  
Incubation Temperature ◽  
Biogas Production ◽  
Substrate Utilization ◽  
Gas Production ◽  
Biomass Growth ◽  
Growth Substrate ◽  
Wide Range ◽  
Modelling Approach

Clostridium phytofermentans, a newly isolated mesophilic anaerobic bacterium from forest soil, has received considerable attention for its potential application in producing ethanol directly from cellulose. This microorganism produces ethanol, acetate, CO₂ and H₂ as major metabolites from cellulose. Potential applications of this research include the transformation of waste materials into valuable products, such as fuels and organic acids. As an initial part of a multi-staged project, this study is to focus on the characerization of this microorganism growth and to verify the bacterium kinetics, including biomass growth, substrate utilization, and gas production. A series of batch fermentation experiments using cellulose substrate (GS-2C) was performed under the incubation temperature of 37°C. To investigate the effects of pH and substrate concentration (S₀) on growth, 12 trial experiments were conducted with various controlled pH values (7.0 to 8.5) and with various initial cellulose concentration settings (0.1 to 6.0 g/L). Our experimental results showed that the optimal growth condition for C. phytofermentans in batch culture was at pH = 8.4 amd S₀ = 6.0 g/L. Under such condition, the maximum growth rate of 0.37h⁻¹ was observed. Comparing results with other celluloytic clostridium studies, relatively high biomass growth rate using C. phytofermentans is confirmed by our experiments. Mathematical models, using a combination modelling approach with the logistic equation. Monod model, and Luedeking-Piret model, were developed for biomass growth, substrate degradation, and biogas production, respectively, base on our experiment results. This study demonstrated the determination of the four parameters (µmax, Ks, Y, and Smin), which can describe satisfactorily growth or degradation phenomena, using the proposed integration modelling approach. The experiments conducted under wide range conditions, such as changing pH and S₀, not only provide insight into growth kinetics but also provide an opportunity to evaluate the performance of the mathematical models and understand their limitations. This leads to look for improvement or modification to the models. It is foreseen that the findings in this study will enhance the overall understanding of the kinetics of growth and substrate utilization and product formation of this bacterium, and provide important information on the design of the bench-scale anaerobic bioreactor for future studies.

scholarly journals Investigation of a new effective bacterium for cellulosic degradation

2021 ◽  
Author(s):  
Weining Lin
Keyword(s):  
Growth Rate ◽  
Mathematical Models ◽  
Incubation Temperature ◽  
Biogas Production ◽  
Substrate Utilization ◽  
Gas Production ◽  
Biomass Growth ◽  
Growth Substrate ◽  
Wide Range ◽  
Modelling Approach

Clostridium phytofermentans, a newly isolated mesophilic anaerobic bacterium from forest soil, has received considerable attention for its potential application in producing ethanol directly from cellulose. This microorganism produces ethanol, acetate, CO₂ and H₂ as major metabolites from cellulose. Potential applications of this research include the transformation of waste materials into valuable products, such as fuels and organic acids. As an initial part of a multi-staged project, this study is to focus on the characerization of this microorganism growth and to verify the bacterium kinetics, including biomass growth, substrate utilization, and gas production. A series of batch fermentation experiments using cellulose substrate (GS-2C) was performed under the incubation temperature of 37°C. To investigate the effects of pH and substrate concentration (S₀) on growth, 12 trial experiments were conducted with various controlled pH values (7.0 to 8.5) and with various initial cellulose concentration settings (0.1 to 6.0 g/L). Our experimental results showed that the optimal growth condition for C. phytofermentans in batch culture was at pH = 8.4 amd S₀ = 6.0 g/L. Under such condition, the maximum growth rate of 0.37h⁻¹ was observed. Comparing results with other celluloytic clostridium studies, relatively high biomass growth rate using C. phytofermentans is confirmed by our experiments. Mathematical models, using a combination modelling approach with the logistic equation. Monod model, and Luedeking-Piret model, were developed for biomass growth, substrate degradation, and biogas production, respectively, base on our experiment results. This study demonstrated the determination of the four parameters (µmax, Ks, Y, and Smin), which can describe satisfactorily growth or degradation phenomena, using the proposed integration modelling approach. The experiments conducted under wide range conditions, such as changing pH and S₀, not only provide insight into growth kinetics but also provide an opportunity to evaluate the performance of the mathematical models and understand their limitations. This leads to look for improvement or modification to the models. It is foreseen that the findings in this study will enhance the overall understanding of the kinetics of growth and substrate utilization and product formation of this bacterium, and provide important information on the design of the bench-scale anaerobic bioreactor for future studies.

The role of hatchling size in generating the intrinsic size-at-age variability of cephalopods: extending the Forsythe Hypothesis

2004 ◽  
Vol 55 (4) ◽  
pp. 387 ◽  
Author(s):  
G. T. Pecl ◽  
M. A. Steer ◽  
K. E. Hodgson
Keyword(s):  
Growth Rate ◽  
Incubation Temperature ◽  
Adult Size ◽  
Daily Growth ◽  
Wide Range ◽  
Extreme Variability ◽  
Effects Of Temperature ◽  
Size At Age ◽  
Hatchling Size

Cephalopods are characterised by extreme variability in size-at-age, with much of this variation attributed to effects of temperature and food. However, even siblings reared under identical conditions display a wide range of sizes after a period of growth. Hatchling size may represent a source of variation encompassed within adult size-at-age data (i) within a given cohort (variation in hatchling size suggests that a cohort’s growth trajectory will have a ‘staggered start’) and (ii) as hatchling size also varies as a function of incubation temperature this will vary across broader scales (i.e. between cohorts). Field-hatchling size data for Sepioteuthis australis were used in simple deterministic simulations, extending Forsythe’s (1993) temperature hypothesis, to investigate the influence of hatchling size on adult size-at-age variability. Within a cohort, our growth projections suggest that after 90 days, a large hatchling growing at a specific constant percentage daily growth rate (%BW day–1), would be approximately double the size of the small hatchling growing at exactly the same rate, irrespective of the growth rate used. When considering growth of different cohorts, decreases in hatchling size, as temperatures increase during a spring/summer spawning season, may be partially counteracting the ‘Forsythe-effect’ of increased growth rate at higher temperatures.

scholarly journals To the problems of wastewater treatment from mineral pollutants with the use of microalgae

2021 ◽  
Vol 6 (1) ◽  
pp. 15-20
Author(s):  
Vasil Dyachok ◽  
◽  
Solomiia Mandryk ◽  
Serhiy Huhlych ◽  
◽  
...  
Keyword(s):  
Growth Rate ◽  
Wastewater Treatment ◽  
Mathematical Models ◽  
Experimental Research ◽  
Experimental Studies ◽  
Pollutant Concentration ◽  
Technological Scheme ◽  
Biomass Growth ◽  
Pollutant Concentrations ◽  
Microalgae Biomass

This article presents the results of experimental studies on the use of Chlorella microalgae for wastewater treatment from the most common mineral pollutants. The influence of the mineral pollutants, namely anions HSO3- , NO3 - , H2PO4 - on the dynamics of wastewater treatment has been established. Analytical dependences of microalgae biomass growth rate depending on pollutant concentration HSO3- , NO3 - , H2PO4 - and are obtained. The values of biomass growth coefficients at the corresponding pollutant concentrations are determined. Based on the obtained experimental research results, mathematical models have been constructed that allow predicting the maximum values of mineral pollutants concentrations at which effective wastewater treatment by chlorophyllsynthesizing microalgae is possible. The technological scheme of wastewater treatment from mineral pollutants and the mechanism of the obtained application biomass are proposed.

Inhibition kinetics for propionate degradation using propionate-enriched mixed cultures

1998 ◽  
Vol 38 (8-9) ◽  
pp. 443-451 ◽  
Author(s):  
S. H. Hyun ◽  
J. C. Young ◽  
I. S. Kim
Keyword(s):  
Phase I ◽  
Competitive Inhibition ◽  
Gas Production ◽  
Phase Iii ◽  
Utilization Rate ◽  
Inhibition Kinetics ◽  
Wide Range ◽  
Propionate Degradation ◽  
Acetate Utilization ◽  
Velocity Coefficient

To study propionate inhibition kinetics, seed cultures for the experiment were obtained from a propionate-enriched steady-state anaerobic Master Culture Reactor (MCR) operated under a semi-continuous mode for over six months. The MCR received a loading of 1.0 g propionate COD/l-day and was maintained at a temperature of 35±1°C. Tests using serum bottle reactors consisted of four phases. Phase I tests were conducted for measurement of anaerobic gas production as a screening step for a wide range of propionate concentrations. Phase II was a repeat of phase I but with more frequent sampling and detailed analysis of components in the liquid sample using gas chromatography. In phase III, different concentrations of acetate were added along with 1.0 g propionate COD/l to observe acetate inhibition of propionate degradation. Finally in phase IV, different concentrations of propionate were added along with 100 and 200 mg acetate/l to confirm the effect of mutual inhibition. Biokinetic and inhibition coefficients were obtained using models of Monod, Haldane, and Han and Levenspiel through the use of non-linear curve fitting technique. Results showed that the values of kp, maximum propionate utilization rate, and Ksp, half-velocity coefficient for propionate conversion, were 0.257 mg HPr/mg VSS-hr and 200 mg HPr/l, respectively. The values of kA, maximum acetate utilization rate, and KsA, half-velocity coefficient for acetate conversion, were 0.216 mg HAc/mg VSS-hr and 58 mg HAc/l, respectively. The results of phase III and IV tests indicated there was non-competitive inhibition when the acetate concentration in the reactor exceeded 200 mg/l.

scholarly journals The simulation model for a flood management by flood control facilities

2018 ◽  
Vol 245 ◽  
pp. 15002 ◽  
Author(s):  
Roman Davydov ◽  
Valery Antonov ◽  
Dmitry Molodtsov ◽  
Alexey Cheremisin ◽  
Vadim Korablev
Keyword(s):  
Mathematical Models ◽  
Flood Control ◽  
Flood Management ◽  
Hydroelectric Power Station ◽  
Hydroelectric Power ◽  
Operating Characteristics ◽  
Hydro Power ◽  
Operation Modes ◽  
Wide Range ◽  
Environmental Requirements

The rapid spread of storm floods over large areas requires flood management throughout the river basin by the creation an innovative system of flood control facilities of various functional purposes distributed in the area. The central part of the system is the hydro system with hydro power plant. In addition, the flood control facilities on the side tributaries with self-regulating reservoir are included in the system. To assess the effect of controlling extreme water discharges by flood control facilities, it is necessary to develop special mathematical models reflecting the specifics of their operation. Unified mathematical models of the operation modes of a hydro complex with hydroelectric power station and flood control facility are created. They are implemented in a computer program that provides the ability to determine the main parameters and operating characteristics of hydro systems when performing multivariate calculations in a wide range of initial data. This makes possible specifying the parameters and operation modes of each hydro system with the current economic and environmental requirements, to assess the energy-economic and environmental consequences in the operation of the system of flood control facilities distributed in the area. The article analyses the results of the extreme water discharge’s regulation by the hydro system on the main river and flood control facilities on the side tributaries, considering environmental requirements.

scholarly journals Characterisation of Lactobacillus rhamnosus VT1 and its effect on the growth of Candida maltosa YP1

2008 ◽  
Vol 25 (No. 5) ◽  
pp. 272-282 ◽  
Author(s):  
D. Liptáková ◽  
Ľ. Valík ◽  
A. Lauková ◽  
V. Strompfová
Keyword(s):  
Growth Rate ◽  
Incubation Temperature ◽  
Lactobacillus Rhamnosus ◽  
Microbial Interactions ◽  
Lag Phase ◽  
Regression Equations ◽  
Candida Maltosa ◽  
Food Protection ◽  
Spoilage Yeast ◽  
Standard Response

The combined effect of initial amount of 18 h <i>L. rhamnosus</i> VT1 inoculum and incubation temperature on the growth of <i>Candida maltosa</i> YP1, an oxidative food spoilage yeast strain, was primarily modelled and studied by standard response surface methodology. This study resulted in the following linear regression equations characterising lag time and growth rate of <i>C. maltosa</i> YP1 in milk in competition with the potentially protective lactobacillus strain. Lag-phase of <i>C. maltosa</i> was strongly influenced by the amount of lactobacillus inoculum (<i>V</i><sub>0</sub>) and incubation temperature (1/<i>T</i>). The synergic effect of both these factors was also evident as results from the equation lag = –33.50 + 186.38 × <i>V</i><sub>0</sub> × 1/<i>T</i> + 512.27 × 1/<i>T</i> – 5.511 × <i>V</i><sub>0</sub> (<i>R</i><sup>2</sup><sub>(λ)</sub> = 0.849). The growth rate was sufficiently described by the linear relation: <i>Gr</i><sub>Cm</sub> = –0.00046 + 0.0033 × <i>T</i> – 0.0016 × <i>V</i><sub>0 (<i>R</i><sup>2</sup><sub>(Gr)</sub> = 0.847). On the basis of these equations, the mutual microbial interactions and the potential application of the lactobacillus strains to food protection are discussed.

scholarly journals Interdependence of friction, wear, and noise: A review

Friction ◽  
2021 ◽  
Author(s):  
Kevin Lontin ◽  
Muhammad Khan
Keyword(s):  
Mathematical Models ◽  
Friction And Wear ◽  
Review Paper ◽  
Acoustic Noise ◽  
Friction Noise ◽  
Mathematical Expressions ◽  
Mechanical Contacts ◽  
Exact Relationship ◽  
Modelling Approach ◽  
Frictional Noise

AbstractPhenomena of friction, wear, and noise in mechanical contacts are particularly important in the field of tribomechanics but equally complex if one wants to represent their exact relationship with mathematical models. Efforts have been made to describe these phenomena with different approaches in past. These efforts have been compiled in different reviews but most of them treated friction, wear mechanics, and acoustic noise separately. However, an in-depth review that provides a critical analysis on their interdependencies is still missing. In this review paper, the interdependencies of friction, wear, and noise are analysed in the mechanical contacts at asperitical level. The origin of frictional noise, its dependencies on contact’s mechanical properties, and its performance under different wear conditions are critically reviewed. A discussion on the existing mathematical models of friction and wear is also provided in the last section that leads to uncover the gap in the existing literature. This review concludes that still a comprehensive analytical modelling approach is required to relate the interdependencies of friction, noise, and wear with mathematical expressions.

scholarly journals Effect of Mixing Regimes on Cow Manure Digestion in Impeller Mixed, Unmixed and Chinese Dome Digesters

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2540
Author(s):  
Abiodun O. Jegede ◽  
Grietje Zeeman ◽  
Harry Bruning
Keyword(s):  
Urban Areas ◽  
Hydraulic Retention Time ◽  
Biogas Production ◽  
Gas Production ◽  
Cow Manure ◽  
Volatile Solid ◽  
Treatment Efficiency ◽  
Ambient Temperatures ◽  
Ch4 Production ◽  
Mixing Regime

This study examines the effect of mixing on the performance of anaerobic digestion of cow manure in Chinese dome digesters (CDDs) at ambient temperatures (27–32 °C) in comparison with impeller mixed digesters (STRs) and unmixed digesters (UMDs) at the laboratory scale. The CDD is a type of household digester used in rural and pre-urban areas of developing countries for cooking. They are mixed by hydraulic variation during gas production and gas use. Six digesters (two of each type) were operated at two different influent total solids (TS) concentration, at a hydraulic retention time (HRT) of 30 days for 319 days. The STRs were mixed at 55 rpm, 10 min/hour; the unmixed digesters were not mixed, and the Chinese dome digesters were mixed once a day releasing the stored biogas under pressure. The reactors exhibited different specific biogas production and treatment efficiencies at steady state conditions. The STR 1 exhibited the highest methane (CH4) production and treatment efficiency (volatile solid (VS) reduction), followed by STR 2. The CDDs performed better (10% more methane) than the UMDs, but less (approx. 8%) compared to STRs. The mixing regime via hydraulic variation in the CDD was limited despite a higher volumetric biogas rate and therefore requires optimization.

Decomposition of Growth Curves into Growth Rate and Acceleration: a Novel Procedure to Monitor Bacterial Growth and the Time-Dependent Effect of Antimicrobials

2021 ◽  
Author(s):  
M. Luisa Navarro-Pérez ◽  
M. Coronada Fernández-Calderón ◽  
Virginia Vadillo-Rodríguez
Keyword(s):  
Growth Rate ◽  
Mathematical Models ◽  
Bacterial Growth ◽  
Time Course ◽  
Antimicrobial Agents ◽  
Numerical Procedure ◽  
Growth Curves ◽  
Predictive Microbiology ◽  
Insight Into ◽  
Over Time

In this paper, a simple numerical procedure is presented to monitor the growth of Streptococcus sanguinis over time in the absence and presence of propolis, a natural antimicrobial. In particular, it is shown that the real-time decomposition of growth curves obtained through optical density measurements into growth rate and acceleration can be a powerful tool to precisely assess a large range of key parameters [ i.e. lag time ( t 0 ), starting growth rate ( γ 0 ), initial acceleration of the growth ( a 0 ), maximum growth rate ( γ max ), maximum acceleration ( a max ) and deceleration ( a min ) of the growth and the total number of cells at the beginning of the saturation phase ( N s )] that can be readily used to fully describe growth over time. Consequently, the procedure presented provides precise data of the time course of the different growth phases and features, which is expected to be relevant, for instance, to thoroughly evaluate the effect of new antimicrobial agents. It further provides insight into predictive microbiology, likely having important implications to assumptions adopted in mathematical models to predict the progress of bacterial growth. Importance: The new and simple numerical procedure presented in this paper to analyze bacterial growth will possibly allow identifying true differences in efficacy among antimicrobial drugs for their applications in human health, food security, and environment, among others. It further provides insight into predictive microbiology, likely helping in the development of proper mathematical models to predict the course of bacterial growth under diverse circumstances.

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