Maximum Growth Rate Research Articles

Изменение бактериального фитнеса в ходе экспериментальной адаптации Pseudomonas aeruginosa к колистину

Pseudomonas aeruginosa, the opportunistic pathogen, occupies one of the leading places in the structure of pathogens causing nosocomial infections, which is due to high adaptive potential and the ability to quickly develop antimicrobial resistance. The study aimed to assess the influence of the P. aeruginosa adaptation to colistin on bacterial fitness. A total of nine isolates obtained during the experimental evolution of the P. aeruginosa strain (laboratory number 1202) under conditions of increasing colistin concentrations, the growth kinetics of which was compared to that of wild type strain, were included in the study; the whole genome sequencing of all isolates was performed, and the minimum inhibitory concentration of colistin was determined. Growth rate was estimated using the Varioskan LUX multimodal reader (Thermo Scientific, USA) throughout 18 h at 37 °С; optical density (OD) at λ = 600 nm was measured every 15 min. The maximum growth rate (GRmax, i.e. the maximum change in OD within 1h) and the time to reach 50% of the maximum OD reported when growing the wild type Ра_1202_0 strain (T_OD50%) were considered. Isolates of the clone carrying mutations of the genes phoQ, lptA, and prs showed low fitness values compared to wild type strains. For example, GRmax of the isolate Ра_1202_43 was 0.029 OD/h vs. 0.182 OD/h reported for the original isolate Ра_1202_0, and it reached OD50% 4.6 h later. The growth characteristics of the clone carrying mutations of lpxL and lptB, as well as the clone carrying mutant pmrB were generally comparable with the characteristics of the wild type strain. Thus, the genome modifications observed during the P. aeruginosa adaptation to colistin have an ambiguous effect on bacterial fitness.

Impact of Nanomaterial in the Marine Environment: Through Mathematical Modelling by Eco-Path Framework

We propose and analyze a simple modification to the Rosenzweig-MacArthur predator (zooplankton)-prey (phytoplankton) model to account for the interference of the predators with the impacts of nanoparticles. We have taken into account the influence of predators by quantifying the impact of nanoparticles in actual environments. It is shown that the influence of the nanoparticles may reduce the prey's maximum physiological per-capita growth rate. An elementary Lotka-Volterra uptake term is taken into consideration in order to investigate the nanoparticle dynamics or interactions. Most importantly, our research shows that phytoplankton growth suppression caused by nanoparticles can destabilize the system and cause periodic oscillation. Additionally, it was demonstrated that a decrease in the equilibrium densities of both phytoplankton and zooplankton might occur from an increase in the rate of interaction between the nanoparticles and phytoplankton. Additionally, the study shows that the stable coexistence of the system dynamics depends critically on the aquatic system's nanoparticles being depleted. We also looked into the system using different kinds of functional reactions. Compared to other commonly used ecology, The complex relationship that exists between phytoplankton and nanoparticles in the natural environment is better described by the Monod-Haldane functional response.

Effect of temperature anisotropy formed by fast electron beams moving in the flare loop on its excited electron-cyclotron maser instability

Context. The electron-cyclotron maser instability (ECMI) is a significant coherent radio emission mechanism widely utilized in various astrophysical radio phenomena. It is well known that the velocity anisotropic distribution of energetic electrons, which leads to an inverted perpendicular population in the vertical direction with ∂fb/∂v⊥ > 0, can provide the free energy necessary for the ECMI. Aims. The initial velocity distribution of energetic electrons leaving the acceleration region is typically isotropic or beam-like. However, as these energetic electrons travel along the magnetic field as fast electron beams (FEBs) in magnetic plasma, various velocity anisotropic distributions can emerge. In this paper, we examine the impact of temperature anisotropy formed by beam electrons traveling along a flare loop on the ECMI. Methods. By neglecting the energy loss of energetic electrons as they traverse the corona and invoking the conservation of energy and magnetic moments, we established the relationship between momentum dispersion and the magnetic field. Utilizing the magnetic field model of the flare loop, we calculated the evolution of momentum dispersion and the growth rates of the ECMI as FEBs precipitate along the flare loop. Results. The results demonstrate that the temperature anisotropy arising as FEBs descend along the flare loop significantly impacts the ECMI. The maximum growth rates of the excited modes exhibit a gradual increase initially and then decline rapidly after reaching a critical height for β0 = 0.2c and 0.15c. The results also show that the growth rates of the O2 mode are one order of magnitude smaller than those of the O1 and X2 modes. This indicates that the harmonic radiation is X-mode polarized. Notably, the temperature anisotropy of FEBs as they precipitate along the flare loop with different magnetic field models or at different heights has similar effects on the ECMI.

Growth rate dalam sektor barang baku dan primer di Bursa Efek Indonesia: Mana lebih baik?

The Sustainable Growth Rate is the maximum growth rate of a company so that it can grow without running out of funds from funding activities such as increasing shareholder capital ownership and drawing loans from creditors. This study measured, tested, and analyzed factors affecting sustainable growth. Some of the factors used in this study are leverage, profitability, and total asset turnover. This study uses objects from raw material sector companies and primary sector companies listed on the Indonesia Stock Exchange for 2018 - 2022, during which data collection was carried out using the purposive sampling method. The form of research used is associative research, a method that examines the relationship between variables, with a quantitative approach. The research data is based on secondary data, namely the company's annual financial report, which is available and has been audited by an independent auditor. Data processing uses multiple linear regression. The study results show that Leverage (DER) and Profitability (ROA) positively affect sustainable growth, providing practical insights for financial analysts and professionals in the raw material and primary sector industries. Total asset turnover (TATO) does not affect the sustainable growth rate. This study also shows that raw material sector companies have a higher sustainable growth rate than primary sector companies.

Effect of different combinations of feed material of cattle dung with kitchen waste on growth rate of earthworm Eutyphoeus waltoni Michaelsen

In this study the effect of different combinations of animal dung (buffalo, cow, and goat) with kitchen wastes (vegetable wastes and banana peels) on the growth rate of Eutyphoeus waltoni during vermicomposting has been investigated. To identify the most potential feed material combination for enhancement of earthworm growth, the experiment was conducted using different combination of animal dung with kitchen waste as well as dung alone. Significant growth rate of Eutyphoeus waltoni was observed in all the binary combinations of animal dung with vegetable waste and banana peels whereas; the maximum growth rate was observed in the combination of buffalo dung and vegetable waste present in (1:1) ratio. It may be due to the balanced nutrient profile provided by the mixture, which enhances the decomposition process and creates an ideal environment for earthworm growth. The feed material combination of buffalo dung and vegetable waste in (1:1) ratio is suitable for better growth and development of earthworm Eutyphoeus waltoni which not only enhances the growth rate of earthworm but also contribute to efficient waste management by converting organic waste into nutrient-rich vermicompost.

Optimal resource allocation in micro-organisms under periodic nutrient fluctuations

Although microorganisms often live in dynamic environments, most studies, both experimental and theoretical, are carried out under static conditions. In this work, we investigate the issue of optimal resource allocation in bacteria growing in periodic environments. We consider a dynamic model describing the microbial metabolism under varying conditions, involving a control variable quantifying the protein precursors allocation. Our objective is to determine the optimal strategies maximizing the long-term growth of cells under a piecewise-constant periodic environment. Firstly, we perform a theoretical analysis of the resulting optimal control problem (OCP), based on the application the Pontryagin’s Maximum Principle (PMP). We determine that the structure of the optimal control must be bang–bang, with possibly some singular arcs corresponding to optimal equilibria of the system. If the control presents singular arcs, then these can only be reached and left through chattering arcs. We also use a direct optimization method, implemented in the BOCOP software, to solve the studied OCP. Our study reveals that the optimal solution over a large time horizon is related to the one over a single period of the varying environment with periodic constraints. Moreover, we observe that the maximal average growth rate attainable under periodic conditions can be higher than the one under a constant environment. We further extend our analysis to conduct a qualitative comparison between the predictions from our model and some recent biological experiments on E. coli. This analysis particularly highlights the mechanisms of action of the ppGpp signaling molecule, thus providing relevant explanations of the experimental observations. In conclusion, our study corroborates previous research indicating that this molecule plays a crucial role in the regulation of resource allocation of protein precursors in E. coli.

Влияние возраста первого отела на молочную продуктивность и качество молока

Nowadays, in order to reduce the cost of replacement heifers raising, early insemination and, accordingly, earlier use of cows are practiced in many farms. The purpose of the research is to study the relationship between milk productivity and the age of the first insemination of Holstein heifers under the conditions of OOO Kaluzhskaya Niva (a limited liability company under the laws of Russian Federation) in the Peremyshl district. The experimental groups were formed from cows with completed fourth lactation, taking into account the age of the first fruitful insemination. As the result of the study, it was found out that the optimal insemination index is observed at heifers of the first and second groups upon reaching the age of 12-14 months with a live weight of 337.6-340.9 kg. The shortage of live weight of heifers by the age of 12 months lengthens the time of raising, and reduces the effectiveness of their insemination (group 4 – the multiplicity of insemination is 3.3). The maximum growth rate was observed at heifers of the first group and made 865-931 g/day, which is 6.1-32.1% higher than in heifers of the other groups. When analyzing the dairy productivity of cows, there is a tendency to decrease the level at the second and third lactations, and an increase in the fourth lactation in comparison with the first one. More balanced lactation activity in a number of lactations is observed in cows of the third group (II lactation decreased by 2%, III - decreased by 5%, IV – increased by 17.5%, compared with the first lactation). At the same time, the variation in milk yield in cows of the other groups ranges from -9.2% to +20.6%. The differences in the indicators of the mass fraction of fat and the mass fraction of protein in milk of cows of different groups are not significant. The tendency of decrease of the mass fraction of fat in milk in cows of all groups is noted by the 4th lactation, with increase in the mass fraction of protein. Thus, for the manifestation of high milk productivity and its preservation in a number of lactation, the optimal age for the first insemination of Holstein heifers is 15-16 months.

Pollution control and biodiesel production with microalgae: new perspectives on the use of flat panel photobioreactors regarding variation in volume application rate.

In the present study, the microalga Arthrospira platensis DHR 20 was cultivated in vertical flat-plate photobioreactors (FPBRs) to bioremediate anaerobically digested cattle wastewater (ACWW) and used as a growth substrate. The final objective was to evaluate the properties of the oil extracted from this biomass to determine its potential for biodiesel production. The process was divided into five phases, varying the volume of the applied substrate: 1 L (Phase I), 5 L (Phase II), 10 L (Phase III), 15 L (Phase IV), and 20 L (Phase V). Dry biomass reached a maximum of 5.7g L-1, and productivity peaked at 0.74g L-1d-1. The highest rate of CO2 biofixation was 1213.5mg L-1day-1, showing good potential for purifying the air. The highest specific maximum growth rate (μmax) and the shortest doubling time (Dt) were found during Phase I. The removal of pollutants and nutrients during the experimental phases ranged from 65.8% to 87.1% for chemical oxygen demand (COD), 82.2% to 85.8% for total organic carbon (TOC), 91% to 99% for phosphate (PO43-), 62.5% to 93% for nitrate (NO3-), 90.4% to 99.7% for ammoniacal nitrogen (NH4+), and 86.5% to 98.5% for total nitrogen (TN). The highest lipid production recorded was 0.172g L-1day-1. The average cetane number recorded in Phase IV of 51 suggests that the fuel will ignite efficiently and consistently, providing smooth operation and potentially reducing pollutant emissions. The analysis of fatty acids revealed that the produced biodiesel has the potential to be used as an additive for other low-explosive biocombustibles, representing an innovative and sustainable approach that simultaneously offers bioremediation and carbon sequestration.

Unraveling the impact of pH, sodium concentration, and medium osmolality on Vibrio natriegens in batch processes

BackgroundVibrio natriegens, a halophilic marine γ-proteobacterium, holds immense biotechnological potential due to its remarkably short generation time of under ten minutes. However, the highest growth rates have been primarily observed on complex media, which often suffer from batch-to-batch variability affecting process stability and performance. Consistent bioprocesses necessitate the use of chemically defined media, which are usually optimized for fermenters with pH and dissolved oxygen tension (DOT) regulation, both of which are not applied during early-stage cultivations in shake flasks or microtiter plates. Existing studies on V. natriegens’ growth on mineral media report partially conflicting results, and a comprehensive study examining the combined effects of pH buffering, sodium concentration, and medium osmolality is lacking.ResultsThis study evaluates the influence of sodium concentration, pH buffering, and medium osmolality on the growth of V. natriegens under unregulated small-scale conditions. The maximum growth rate, time of glucose depletion, as well as the onset of stationary phase were observed through online-monitoring the oxygen transfer rate. The results revealed optimal growth conditions at an initial pH of 8.0 with a minimum of 300 mM MOPS buffer for media containing 20 g/L glucose or 180 mM MOPS for media with 10 g/L glucose. Optimal sodium chloride supplementation was found to be between 7.5 and 15 g/L, lower than previously reported ranges. This is advantageous for reducing industrial corrosion issues. Additionally, an osmolality range of 1 to 1.6 Osmol/kg was determined to be optimal for growth. Under these optimized conditions, V. natriegens achieved a growth rate of 1.97 ± 0.13 1/h over a period of 1 h at 37 °C, the highest reported rate for this organism on a mineral medium.ConclusionThis study provides guidelines for cultivating V. natriegens in early-stage laboratory settings without pH and DOT regulation. The findings suggest a lower optimal sodium chloride range than previously reported and establish an osmolality window for optimal growth, thereby advancing the understanding of V. natriegens’ physiology. In addition, this study offers a foundation for future research into the effects of different ions and carbon sources on V. natriegens.

Temperature-dependent alterations in the proteome of the emergent fish pathogen Edwardsiella piscicida.

Edwardsiella piscicida is an emerging bacterial pathogen and the aetiological agent of edwardsiellosis among cultured and wild fish species globally. The increased frequency of outbreaks of this Gram-negative, facultative intracellular pathogen pose not only a threat to the aquaculture industry but also a possible foodborne/waterborne public health risk due to the ill-defined zoonotic potential. Thus, understanding the role of temperature on the virulence of this emerging pathogen is essential for comprehending the pathogenesis of piscine edwardsiellosis in the context of current warming trends associated with climate change, as well as providing insight into its zoonotic potential. In this study, significant temperature-dependent alterations in bacterial growth patterns were observed, with bacterial isolates grown at 17°C displaying higher peak growth sizes, extended lag times, and slower maximal growth rates than isolates grown at 27or 37°C. When E. piscicida isolates were grown at 37°C compared to 27 and 17°C, mass spectrometry analysis of the E. piscicida proteome revealed significant downregulation of crucial virulence proteins, such as Type VI secretion system proteins and flagellar proteins. Although invivo models of infection are warranted, this invitro data suggests possible temperature-associated alterations in the virulence and pathogenic potential of E. piscicida in poikilotherms and homeotherms.

On EMEC Instability in Bi‐Kappa Distributed Space Plasmas Under the Influence of Parallel DC Electric Field

ABSTRACTEMEC waves driven by kinetic anisotropies and suprathermal particles are expected to play an important role at dissipative scales in the solar wind and planetary magnetospheres. Moreover, the correlation of EMEC waves with electric field magnitude and direction can be a tool to probe the inner magnetosphere. Thus, in this manuscript, we present the study of EMEC waves driven by temperature anisotropy in bi‐Kappa distributed space plasmas in the presence of a parallel DC electric field. The dispersion equation bearing the influence of electric field and suprathermal particles followed by the analytical expressions for wave frequency and wave growth rate is derived. The general dispersion equation is solved numerically to unveil the effect of suprathermal particles, temperature anisotropy, and the magnitude of the electric field on growth rate as well as the domain of unstable wave numbers, and the obtained numerical outcomes are compared with those of the bi‐Maxwellian model. Moreover, the maximum growth rates for EMEC waves have also been obtained.

Simulation of Interfacial Waves in Core-Annular Pipe Flow with a Turbulent Annulus

Abstract Numerical simulations are conducted for the wave initiation, growth, and saturation at the oil-water interface in core-annular flow. The focus is on conditions with a turbulent water annulus, but the laminar water annulus is also considered. The simulation results are compared with lab measurements. The growth rate for the linear instability of different wave lengths in the case of a turbulent water annulus is obtained from two-dimensional axisymmetric Reynolds-Averaged Navier-Stokes simulations with the Launder-Sharma low-Reynolds number k-e model. The latter simulation results provide the most unstable wave length for the turbulent water annulus. Our study also shows the following. The maximum wave growth rate for a turbulent water annulus is significantly higher than for a laminar water annulus. The most unstable wave length in the simulations is about 25% smaller than in the experiments. The wave amplitude for the different wave lengths in the simulations is typically 17% lower than in the experiments.

Suppression of the superfluid Kelvin-Helmholtz instability due to massive vortex cores, friction and confinement

We characterize the dynamical instability responsible for the breakdown of regular rows and necklaces of quantized vortices that appear at the interface between two superfluids in relative motion. Making use of a generalized point-vortex model, we identify several mechanisms leading to the suppression of this instability. They include a non-zero mass of the vortex cores, dissipative processes resulting from the interaction between the vortices and the excitations of the superfluid, and the proximity of the vortex array to the sample boundaries. We show that massive vortex cores not only have a mitigating effect on the dynamical instability, but also change the associated scaling law and affect the direction along which it develops. The predictions of our massive and dissipative point-vortex model are eventually compared against recent experimental measurements of the maximum instability growth rate relevant to vortex necklaces in a cold-atom platform.

Sensitivity analysis of a hydrodynamic and harmful algal model in a riverine system

Simulating algae blooms using a hydrodynamic-water quality model is challenging because it requires a thorough understanding of physical and biological processes and involves numerous parameters. This study conducted a sensitivity analysis of the EFDC+ hydrodynamic and water quality model for simulating cyanobacteria growth, an important Harmful Algal Bloom (HAB) species in the Ohio River, USA. The sensitivity analysis assessed 23 model input parameters, divided into nine functional groups according to their characteristics. This assessment analyzes the impact of changing these input parameters on four water quality model outputs including algae (i.e., cyanobacteria), dissolved oxygen, total nitrogen, and total phosphorus. Light extinction parameters, maximum algal growth rate, and algal base metabolism were identified as the most sensitive parameters for simulating algal growth. Solar radiation required for algal growth was moderately sensitive. Currently, there are only a few studies that simulate HAB dynamics in riverine systems. This study deepens our understanding of HAB development in rivers with lock and dam structures that create a series of pools along the river. Future work will involve focusing on the sensitive parameters in model calibration.

Nutrient availability influences the thermal response of marine diatoms

AbstractUnderstanding how phytoplankton growth responds to temperature is critical for forecasting marine productivity in a warming ocean. While previous laboratory studies have shown that phytoplankton thermal traits such as optimal temperature (Topt) can be affected by nutrient availability, it is unclear whether this can be extrapolated to natural communities. To address this, we tested the impacts of nutrient availability on the thermal responses of two cosmopolitan diatom genera, Pseudo‐nitzschia and Leptocylindrus, through a series of in situ manipulation experiments on natural phytoplankton communities. Analysis of the thermal performance curves revealed that nutrient limitation during summer not only limited the growth of these two genera but also reduced their Topt and the maximum growth rates (μmax). Topt was close to or lower than in situ temperature under ambient nutrient conditions, suggesting that further warming may have a detrimental effect on their growth. However, increasing nutrient supply could counteract this by enhancing Topt and μmax. To further confirm the interactive effects of nutrients and temperature on diatoms, we analyzed a 20‐yr monitoring dataset on Pseudo‐nitzschia, Leptocylindrus, and the whole diatom assembly in Hong Kong coastal waters. We found that the abundances of marine diatoms were significantly higher at high temperatures under nutrient‐rich environments while relatively low under low nutrient concentrations. Findings on natural diatom cell density align with the growth performance derived from in situ manipulation experiments, suggesting that abundant nutrients bolster marine diatoms in coping with warming. Our results highlight the importance of considering the influence of nutrient availability on thermal response of phytoplankton growth, which sheds light on how marine primary production may change under climate warming.

Engineering the cell wall reactive groups of Plant Growth Promoting Rhizobacteria by culture strategy for heavy metal removal

This research delved into the effects of nutrient limitation on the level of sporulation and the cadmium adsorption capacity of the bacterium Bacillus sp. isolated from the rhizosphere of endemic soils in the Region of Valparaiso, Chile. The bacteria were subjected to nitrogen limitation in fed-batch mode and were compared to bacteria grown in batch culture without nutrient limitation. The cultures were carried out in a 3 L bioreactor with an external nitrogen supply of ammonium at a flow of 0.123 L h−1. The specific maximum growth rate was 0.42 h−1 in batch and 0.45 h−1 in the exponential phase of the fed-batch.The analysis of sporulation did not show any significant difference between the biomass coming from the fed-batch and batch cultures.It was found that maximum cadmium adsorption capacity varied with culture strategy. The dry biomass grown without nutrient limitation exhibited a maximum adsorption capacity for cadmium of 65.0 mgCd g−1biomass. Conversely, the limited biomass achieved a lower cadmium adsorption capacity of approximately 36.0 mgCd g−1biomass. FTIR analysis showed that nitrogen limitation induced changes in the composition of the outer cell wall, specifically an increase of deacetlylated polysaccharides, reducing the relative amount of secondary amines and proteins from the peptidoglycan matrix. Amino groups from acetylated polysaccharides and proteins have been associated elsewhere with greater cadmium affinity, which could explain the poor results obtained with the nitrogen-restricted biomass. This study shows that new physiological states displaying different adsorption capabilities were effectively obtained by engineering the cell coverage of the bacteria using varying culture strategies. The fed-batch culture proved to be a valuable tool for studying PGPR strains for biosorption and other applications. Exploring diverse nutrient limitations and other pollutants in this bacterium and other members of the PGPR family offer great opportunities to tailor biosorption strategies based on specific conditions, ultimately contributing to sustainable environmental solutions.

Effects of Water and Nitrogen Regulation on Apple Tree Growth, Yield, Quality, and Their Water and Nitrogen Utilization Efficiency.

Apple tree productivity is influenced by the quantity of water and nutrients that are supplied during planting. To enhance resource utilization efficiency and optimize yields, a suitable strategy for supplying water and nitrogen must be established. A field experiment was conducted using a randomized block group design on five-year-old apple trees in Ningxia, with two irrigation lower limit levels (55%FC (W1) and 75%FC (W2)) and four N application levels (0 (N1), 120 (N2), 240 (N3), and 360 (N4) kg·ha-1). Our findings showed that leaf N content increased with a higher irrigation lower limit, but the difference was not statistically significant. However, the leaf N content significantly increased with increasing N application. The growth pattern of new shoots followed logistic curve characteristics, with the maximum new shoot growth rate and time of new shoot growth being delayed under high water and high nitrogen treatments. Apple yield and yield components (weight per fruit and number of fruits per plant) were enhanced under N application compared to no N application. The maximum apple yields were 19,405.3 kg·ha-1 (2022) and 29,607 kg·ha-1 (2023) at the N3 level. A parabolic relationship was observed between apple yield and N application level, with the optimal range of N application being 230-260 kg⸱ha-1. Apple quality indicators were not significantly affected by the irrigation lower limit but were significantly influenced by N application levels. The lower limit of irrigation did not have a significant impact on the quality indicators of the apples. Water and N utilization efficiencies improved with the W2 treatment at the same N application level. A negative relationship was observed between the amount of nitrogen applied and the biased productivity of nitrogen fertilizer. The utilization of nitrogen fertilizer was 127.6 kg·kg-1 (2022) and 200.3 kg·kg-1 (2023) in the W2N2 treatment. The apple yield was sustained, the quality of the fruit improved, and a substantial increase in water productivity was achieved with the W2N3 treatment. The findings of this study can be used as a reference for accurate field irrigation.

Analysis of the yield of spring oats cultivated in a harsh continental climate

Studies of the yield of spring oats for the period 2012–2021 in the conditions of a sharply continental climate in the Kemerovo region have been carried out. The main soils of the steppe zone are leached heavy loamy chernozem, forest-steppe — gray forest. In 2012, the yield of this crop was the lowest — 9.35 kg/ha. The first one reflects the trend of yield dynamics (trend) and is associated with an increase in the general culture of agriculture. The second is caused by fluctuations in weather conditions in each particular year and is depicted as deviations from the trend. It is shown that the yield of spring oats in both steppe and forest-steppe soil-climatic zones tends to slightly increase. The analysis of the data obtained showed that the maximum yield of spring oats was in 2021 — 22.68 kg/ha, and the lowest was in 2012 (9.35 kg/ha). The high fluctuation of oat yield indicates a strong influence of hydrothermal conditions during the growing season of the crop. It was found that the decrease in the growth rate of spring oat yields in the Kemerovo region was in 2015, 2016 and 2018. The maximum growth rate was observed in 2013 — 178.82%. The maximum decrease in the yield growth rate of spring oats occurred in 2016 and 2018 - by -5.31% and -6.68%, respectively. The highest increase in oat yield was observed in 2013 — 78.82%. The absolute content of 1% yield increase was 19.44 c/ha in 2021 compared to 2012.

Cell Geometry and Membrane Protein Crowding Constrain Growth Rate, Overflow Metabolism, Respiration, and Maintenance Energy.

A metabolic theory is presented for predicting maximum growth rate, overflow metabolism, respiration efficiency, and maintenance energy flux based on the intersection of cell geometry, membrane protein crowding, and metabolism. The importance of cytosolic macromolecular crowding on phenotype has been established in the literature but the importance of surface area has been largely overlooked due to incomplete knowledge of membrane properties. We demonstrate that the capacity of the membrane to host proteins increases with growth rate offsetting decreases in surface area-to-volume ratios (SA:V). This increase in membrane protein is hypothesized to be essential to competitive Escherichia coli phenotypes. The presented membrane-centric theory uses biophysical properties and metabolic systems analysis to successfully predict the phenotypes of E. coli K-12 strains, MG1655 and NCM3722, which are genetically similar but have SA:V ratios that differ up to 30%, maximum growth rates on glucose media that differ by 40%, and overflow phenotypes that start at growth rates that differ by 80%. These analyses did not consider cytosolic macromolecular crowding, highlighting the distinct properties of the presented theory. Cell geometry and membrane protein crowding are significant biophysical constraints on phenotype and provide a theoretical framework for improved understanding and control of cell biology.

Dispersal of a dominant competitor can drive multispecies coexistence in biofilms

Despite competition for both space and nutrients, bacterial species often coexist within structured, surface-attached communities termed biofilms. While these communities play important, widespread roles in ecosystems and are agents of human infection, understanding how multiple bacterial species assemble to form these communities and what physical processes underpin the composition of multispecies biofilms remains an active area of research. Using a model three-species community composed of Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis, we show with cellular-scale resolution that biased dispersal of the dominant community member, P.aeruginosa, prevents competitive exclusion from occurring, leading to the coexistence of the three species. A P.aeruginosa bqsS deletion mutant no longer undergoes periodic mass dispersal, leading to the local competitive exclusion of E.coli. Introducing periodic, asymmetric dispersal behavior into minimal models, parameterized by only maximal growth rate and local density, supports the intuition that biased dispersal of an otherwise dominant competitor can permit coexistence generally. Colonization experiments show that WT P.aeruginosa is superior at colonizing new areas, in comparison to ΔbqsS P. aeruginosa, but at the cost of decreased local competitive ability against E.coli and E.faecalis. Overall, our experiments document how one species' modulation of a competition-dispersal-colonization trade-off can go on to influence the stability of multispecies coexistence in spatially structured ecosystems.