Medium Components Research Articles

Isolation and Characterization of a New High-Yield Hydrogen-Producing Strain, Clostridium sulfidigenes CS3, from Anaerobic Sludge in the To Lich River

Hydrogen is a vital gas, recognized for its role as a renewable, clean energy source and its importance as a feedstock in multiple industries, leading to a significant rise in hydrogen production demand in recent years. In this context, a high-yield hydrogen-producing mesophilic bacterium, strain CS3, was isolated from sludge and identified as Clostridium sulfidigenes CS3 through 16S rRNA gene analysis and physio-biochemical testing, revealing novel characteristics of this species. This study systematically investigated various factors influencing biological hydrogen production through fermentation, including medium components (like substrates and nitrogen sources) and environmental conditions (initial pH, incubation temperature, duration, and agitation). The research also explored methods to boost hydrogen yield. The maximum yield of 2.1 mol H₂/mol glucose was obtained under optimal conditions: a medium with 10 g/L glucose, an initial pH of 7.0, incubation at 37°C for 48 hours, and agitation at 200 rpm, with supplementation of organic nitrogen sources (10 g/L peptone and 10 g/L yeast extract). The performance of C. sulfidigenes CS3 was compared with other known hydrogen-producing strains, highlighting the superior hydrogen productivity of this species. This is also considered a new discovery in the hydrogen-producing ability of this species. The findings suggest that C. sulfidigenes CS3 could be a promising candidate for biohydrogen production, providing an environmentally friendly alternative to fossil fuels.

Research on in vitro propagation techniques of vine-tea plant (Ampelopsis cantoniensis (Hook. and Arn.) Planch)

Vine-tea plant has the scientific name Ampelopsis cantoniensis (Hook. and Arn.) Planch and is a valuable herb plant in Vietnam. This study aimed to find a method to sterilize samples and nutrient medium components in each stage of shoots regeneration, rapid shoots multiplication, complete plant creation and in vitro seedling cultivation in the nursery stage of in vitro propagation techniques of vine-tea plant. Four experiments in research room and one experiment in nursery were conducted from January to December 2023 at Hue University of Agriculture and Forestry, Vietnam. Criterias of infected, alived, clean and dead samples, rate of shoot regeneration and number of shoots/samples were measured. Research results showed that the best medium to regenerate shoots from stem section carrying dormant eyes is MS + 1.5mg BAP/l + 6.5g agar/l + 30g sucrose/l. The best medium to quickly multiply shoots is MS + 1.5 mg BAP/l + 0.2 mg IBA/l + 6.5g agar/l + 30g sucrose/l. The best complete plant-creating medium is MS + 0.5 mg α-NAA/l + 6.5g agar/l + 30g sucrose/l. In the condition that the nursery has a rain cover roof, a black net reduced the light intensity by 70% and the tissue culture nursery substrate of humus soil under the forest canopy + coconut fiber powder + smoked rice husk (1:1:1) gave the best results with survival rate reached 76.67%.

Improvement of Growth Media Quality Using Coconut Coir Dust, Coconut Ash, and Palm Kernel Shell Biochar

<p>The sustainable management of agricultural waste is vital for addressing environmental challenges while enhancing resource efficiency in agriculture. This study aimed to evaluate the potential of agricultural residues, specifically coconut and oil palm by-products, as growth media components. Growth media mixtures were formulated using coconut coir dust (CCD), coconut shell ash (CSA), and palm kernel shell biochar (PKSB), and their physicochemical properties were analyzed. The experiment was conducted in a completely randomized design with three replications. The results indicated that a growth media mixture consisting of 100% CSA demonstrated high pH (7.89), electrical conductivity (2.70 dS m<sup>-1</sup>), cation exchange capacity (12.57 cmolc kg<sup>-1</sup>), and significant concentrations of P (13.90 mg l<sup>-1</sup>) and K (191.70 mg l<sup>-1</sup>), which suggests its suitability as a liming agent. However, this mixture exhibited limitations in aeration and water retention due to low porosity (24.3%). Furthermore, increasing the proportions of CSA and PKSB significantly enhanced the growth media’s bulk density and particle density. These findings provide valuable insights into developing efficient growth media from agricultural by-products, thereby contributing to sustainable waste management and innovative farming practices.</p>

Modeling and optimization of culture media for recombinant Helicobacter pylori vaccine antigen HpaA.

H. pylori (Helicobacter pylori) infection represents a significant global health concern, exacerbated by the emergence of drug-resistant strains resulting from conventional antibiotic treatments. Consequently, the development of vaccines with both preventive and therapeutic properties has become crucial in addressing H. pylori infections. The H. pylori adhesin protein HpaA has demonstrated strong immunogenicity across various adjuvants and dosage forms, positioning it as a key candidate antigen for recombinant subunit vaccines against H. pylori. Optimizing fermentation culture conditions is an effective strategy to enhance product yield and lower production costs. However, to date, there has been no systematic investigation into methods for improving the fermentation yield of HpaA. Enhancing the fermentation medium to increase HpaA yield holds significant potential for application and economic benefits in the prevention and detection of H. pylori infection. To achieve a stable and high-yielding H. pylori vaccine antigen HpaA, this study constructed recombinant Escherichia coli expressing HpaA. The impact of fermentation medium components on the rHpaA yield was assessed using a one-factor-at-a-time approach alongside Plackett-Burman factorial experiments. Optimal conditions were effectively identified through response surface methodology (RSM) and artificial neural network (ANN) statistical computational models. The antigenicity and immunogenicity of the purified rHpaA were validated through immunization of mice, followed by Western Blot analysis and serum IgG ELISA quantification. Glucose, yeast extract, yeast peptone, NH4Cl and CaCl2 all contributed to the production of rHpaA, with glucose, yeast extract, and NH4Cl demonstrating particularly significant effects. The artificial neural network linked genetic algorithm (ANN-GA) model exhibited superior predictive accuracy, achieving a rHpaA yield of 0.61g/L, which represents a 93.2% increase compared to the initial medium. Animal immunization experiments confirmed that rHpaA possesses good antigenicity and immunogenicity. This study pioneers the statistical optimization of culture media to enhance rHpaA production, thereby supporting its large-scale application in H. pylori vaccines. Additionally, it highlights the advantages of the ANN-GA approach in bioprocess optimization.

A short-time, low-dosage chemicals dyeing of polyester/cotton blended fabric with benzothiazole dyes in water-less, salt-free dyeing system

Non-aqueous media dyeing technology has highly innovative as it reduces pollution without increasing cost in polyester/cotton blended fabric dyeing. However, disperse dyes can stain in cotton component of the polyester/cotton blended fabric during dyeing process, resulting poor quality of dyed products. In this study, a groundbreaking comprehensive investigation was conducted on the dyeing behavior of C.I. Disperse Red 177 and C.I. Disperse Red 145 in non-aqueous media. The results revealed that the dyes' uptake rates on polyester components in non-aqueous medium were comparable to those in traditional water dyeing baths. Conversely, the staining rate of disperse dye on cotton fiber surface was relatively high. Interestingly, the migration of dyes from polyester surface to cotton surface after dyeing had minimal impact on staining. Thermodynamic analysis in non-aqueous media showed that the Gibbs free energy of C.I. Disperse Red 145 adsorption on cotton was higher than that of C.I. Disperse Red 177. Computational chemistry simulations showed that the terminal group of C.I. Disperse Red 177 (N-acetoxyethyl) led to stronger electrostatic interaction with cotton compared to C.I. Disperse Red 145. Therefore, disperse dyes with N-ethyl end groups have a weak interaction with the cotton and stain less on the cotton fiber surface.

Impact of components of biorelevant media on solubilization of methotrexate and sulfasalazine by Pluronic F127

Pluronics are micelle-based solubilizers, improving the therapeutic potential of orally administrated drugs. In this connection, solubilizing action of Pluronics is being intensively studied in standard buffers simulating gastrointestinal fluids and consisting of inorganic components. However, human gastrointestinal fluids have more complicate composition due to the presence of organic compounds such as enzymes, mucus, and bile, which are able to form supramolecular aggregates and influence the solubilizing effect of Pluronics. Therefore, the use of specially designed biorelevant media is a promising approach to assessing the effectiveness of solubilizing activity of Pluronics in vitro.Based on this, we studied the solubilization of poorly soluble methotrexate and sulfasalazine, which are used in the treatment of autoimmune and oncological diseases, by Pluronic F127 in Fasted State Simulated Gastric Fluid and Fasted State Simulated Intestinal Fluid. Taurocholic acid and lecithin being the main components of these biorelevant media form micelles and thereby enhance the solubility of drugs that are insoluble or sparingly soluble in water. The affinity of drugs under consideration to the micelles of different nature, which are present in the dissolution medium, is examined in this work. The possible competing interactions of drug-micelle and drug-unimer are discussed in terms of the ionization state of drug molecules and the nature of surfactants.

A data-driven approach for cell culture medium optimization

Cell culture media are critical for cell propagation and bioproduction to be as efficient as possible to meet medical and pharmaceutical requirements. However, optimizing medium composition to achieve optimal cell culture remains a significant challenge due to the complexity of living cells and their required media. This study, which is a significant contribution to the field, addresses the need for data-driven techniques in cell culture technologies by integrating active machine learning (ML) to reformulate a widely used base medium for mammalian cell culture. The optimization process was facilitated by developing various ML models, which accounted for experimental data processing and time consumption. It provided a detailed methodology and essential knowledge for utilizing ML in medium development. Growth determinative medium components were identified through data mining and scale-up culture. In addition, RNA sequencing analysis indicated that active learning finetuned the media for the changes in gene expression for improved cell culture. This study offers new insights and methodologies to be applied to cell culture for future medical purposes.

Arkenstone - II. A model for unresolved cool clouds entrained in galactic winds in cosmological simulations

Abstract Arkenstone is a new scheme that allows multiphase, stellar feedback-driven winds to be included in coarse resolution cosmological simulations. The evolution of galactic winds and their subsequent impact on the circumgalactic medium are altered by exchanges of mass, energy, momentum, and metals between their component phases. These exchanges are governed by complex, small-scale physical processes that cannot be resolved in cosmological simulations. In this second presentation paper, we describe Arkenstone’s novel cloud particle approach for modelling unresolvable cool clouds entrained in hot, fast winds. This general framework allows models of the cloud–wind interaction, derived from state-of-the-art high-resolution simulations, to be applied in a large-scale context. In this work, we adopt a cloud evolution model that captures simultaneous cloud mass loss to and gain from the ambient hot phase via turbulent mixing and radiative cooling, respectively. We demonstrate the scheme using non-cosmological idealized simulations of a galaxy with a realistic circumgalactic medium component, using the Arepo code. We show that the ability of a high-specific energy wind component to perform preventative feedback may be limited by heavy loading of cool clouds coupled into it. We demonstrate that the diverging evolution of clouds of initially differing masses leads to a complex velocity field for the cool phase and a cloud mass function that varies both spatially and temporally in a non-trivial manner. These latter two phenomena can manifest in the simulation because of our choice of a Lagrangian discretisation of the cloud population, in contrast to other proposed schemes.

Measuring 15N and 13C Enrichment Levels in Sparsely Labeled Proteins Using High-Resolution and Tandem Mass Spectrometry.

Isotope labeling of both 15N and 13C in selected amino acids in a protein, known as sparse labeling, is an alternative to uniform labeling and is particularly useful for proteins that must be expressed using mammalian cells, including glycoproteins. High levels of enrichment in the selected amino acids enable multidimensional heteronuclear NMR measurements of glycoprotein three-dimensional structure. Mass spectrometry provides a means to quantify the degree of enrichment. Mass spectrometric measurements of tryptic peptides of a selectively labeled glycoprotein expressed in HEK293 cells revealed complicated isotope patterns which consisted of many overlapping isotope patterns from intermediately labeled peptides, which complicates the determination of the label incorporation. Two challenges are uncovered by these measurements. Metabolic scrambling of amino groups can reduce the 15N content of enriched amino acids or increase the 15N in nontarget amino acids. Also, undefined, unlabeled medium components may dilute the enrichment level of labeled amino acids. The impact of this unexpected metabolic scrambling was overcome by simulating isotope patterns for all isotope-labeled peptide states and generating linear combinations to fit to the data. This method has been used to determine the percent incorporation of 15N and 13C labels and has identified several metabolic scrambling effects that were previously undetected in NMR experiments. Ultrahigh mass resolution is also utilized to obtain isotopic fine structure, from which enrichment levels of 15N and 13C can be assigned unequivocally. Finally, tandem mass spectrometry can be used to confirm the location of heavy isotope labels in the peptides.

Navigating stem cell culture: insights, techniques, challenges, and prospects.

Stem cell research holds huge promise for regenerative medicine and disease modeling, making the understanding and optimization of stem cell culture a critical aspect of advancing these therapeutic applications. This comprehensive review provides an in-depth overview of stem cell culture, including general information, contemporary techniques, encountered problems, and future perspectives. The article begins by explaining the fundamental characteristics of various stem cell types, elucidating the importance of proper culture conditions in maintaining pluripotency or lineage commitment. A detailed exploration of established culture techniques sheds light on the evolving landscape of stem cell culture methodologies. Common challenges such as genetic stability, heterogeneity, and differentiation efficiency are thoroughly discussed, with insights into cutting-edge strategies and technologies aimed at addressing these hurdles. Moreover, the article delves into the impact of substrate materials, culture media components, and biophysical cues on stem cell behavior, emphasizing the intricate interplay between the microenvironment and cell fate decisions. As stem cell research advances, ethical considerations and regulatory frameworks become increasingly important, prompting a critical examination of these aspects in the context of culture practices. Lastly, the article explores emerging perspectives, including the integration of artificial intelligence and machine learning in optimizing culture conditions, and the potential applications of stem cell-derived products in personalized medicine. This comprehensive overview aims to serve as a valuable resource for researchers and clinicians, fostering a deeper understanding of stem cell culture and its key role in advancing regenerative medicine and biomedical research.

The development of a formulation, the selection and harmonization of the nutrient medium for determining the activity of aminoglycoside antibiotics

The work is devoted to research on the selection of peptone for the optimization of the nutrient medium for the antimicrobial activity by the agar diffusion method of neomycin (framycetin), which have a similar chemical structure. The paper substantiates the relevance and importance of developing a formulation, selecting the optimal composition (ingredients), the quantitative ratio of ingredients, the pH of the medium, compliance of the proposed nutrient media with the State Pharmacopoeia of the Russian Federation and the European Pharmacopoeia for the standardization of antibiotics. The aim of the work was to study the components of the nutrient medium in comparison with the pharmacopoeial standards recommended for determining the effectiveness of antibiotics. It is shown that for carrying out microbiological tests in the standardization of antimicrobial drugs, the nutrient medium is the main one, and the correctness and accuracy of the interpretation of the research results depend on their quality. The experiment studied four brands of dry peptone and broth from different manufacturers – LLC NITSF and FBUN GNTs PMB (Obolensk) when working with the test strain of the spore culture Bacillus subtilis ATCC 6633. An optimal nutrient medium is proposed, the composition and conditions of its preparation are selected. To determine the antimicrobial activity of framycetin by the agar diffusion method, a developed medium for determining the effectiveness of neomycin when working with the spore-forming form of the test strain Baccillus subtillis ATCC 6633 is proposed.

Impact of growth medium components on absorbance-viable cell count correlation and cell surface area of Cereibacter sphaeroides O.U.001

Today different methods are used in microbiology laboratories to monitor the growth and development of bacteria. Optical density measurement is one of the most preferred methods as being fast, practical and low cost. On the other hand, it cannot differentiate between living and non-living cells in the culture. Moreover, alteration in cell size may lead to the variations in the measurements. As a result, optical density measurements alone may cause wrong experimental results. Therefore, it is necessary to determine the absorbance-living cell number relationship for each specific culture condition. In this study, Cereibacter sphaeroides O.U.001 was cultured under four different culture conditionsregarding the type of carbon and nitrogen sourc es (Malate/Glutamate, Molasses/Glutamate, Malate/N 2 and Acetate/Glutamate) and the effect of medium composition on cell size and absorbance-viable cell count relationship was investigated. Equations were created from curves drawn as optical density (x-axis) against CFU/mL (y-axis). Field emission scanning electron microscope was used to observe the effects of medium compositions on the size of Cereibacter sphaeroides O.U.001. It was revealed that the composition of the medium affected the absorbance-number of living cells relationship. Furthermore, it was evidenced that the size of the cells was changed significantly upon changing the medium composition. To conclude, it is advised that that before performing experiments in which the cell numbers are significative, a comparative calibration curve for optical density measurement-the living cell number relationship should be established for more accurate results.

Macrophage-derived extracellular vesicles from Ascaris lumbricoides antigen exposure enhance Mycobacterium tuberculosis growth control, reduce IL-1β, and contain miR-342-5p, miR-516b-5p, and miR-570-3p that regulate PI3K/AKT and MAPK signaling pathways.

Helminth coinfection with tuberculosis (TB) can alter the phenotype and function of macrophages, which are the major host cells responsible for controlling Mycobacterium tuberculosis (Mtb). However, it is not known whether helminth infection stimulates the release of host-derived extracellular vesicles (EVs) to induce or maintain their regulatory network that suppresses TB immunity. We previously showed that pre-exposure of human monocyte-derived macrophages (hMDMs) with Ascaris lumbricoides protein antigens (ASC) results in reduced Mtb infection-driven proinflammation and gained bacterial control. This effect was entirely dependent on the presence of soluble components in the conditioned medium from helminth antigen-pre-exposed macrophages. Our objective was to investigate the role of EVs released from helminth antigen-exposed hMDMs on Mtb-induced proinflammation and its effect on Mtb growth in hMDMs. Conditioned medium from 48-h pre-exposure with ASC or Schistosoma mansoni antigen (SM) was used to isolate EVs by ultracentrifugation. EVs were characterized by immunoblotting, flow cytometry, nanoparticle tracking assay, transmission electron microscopy, and a total of 377 microRNA (miRNA) from EVs screened by TaqMan array. Luciferase-expressing Mtb H37Rv was used to evaluate the impact of isolated EVs on Mtb growth control in hMDMs. EV characterization confirmed double-membraned EVs, with a mean size of 140 nm, expressing the classical exosome markers CD63, CD81, CD9, and flotillin-1. Specifically, EVs from the ASC conditioned medium increased the bacterial control in treatment-naïve hMDMs and attenuated Mtb-induced IL-1β at 5 days post-infection. Four miRNAs showed unique upregulation in response to ASC exposure in five donors. Pathway enrichment analysis showed that the MAPK and PI3K-AKT signaling pathways were regulated. Among the mRNA targets, relevant for regulating inflammatory responses and cellular stress pathways, CREB1 and MAPK13 were identified. In contrast, SM exposure showed significant regulation of the TGF-β signaling pathway with SMAD4 as a common target. Overall, our findings suggest that miRNAs in EVs released from helminth-exposed macrophages regulate important signaling pathways that influence macrophage control of Mtb and reduce inflammation. Understanding these interactions between helminth-induced EVs, miRNAs, and macrophage responses may inform novel therapeutic strategies for TB management.

Cold Gas Subgrid Model (CGSM): a two-fluid framework for modelling unresolved cold gas in galaxy simulations

ABSTRACT The cold ($\sim 10^{4}\, {\rm K}$) component of the circumgalactic medium (CGM) accounts for a significant fraction of all galactic baryons. However, using current galaxy-scale simulations to determine the origin and evolution of cold CGM gas poses a significant challenge, since it is computationally infeasible to directly simulate a galactic halo alongside the sub-pc scales that are crucial for understanding the interactions between cold CGM gas and the surrounding ‘hot’ medium. In this work, we introduce a new approach: the Cold Gas Subgrid Model (CGSM), which models unresolved cold gas as a second fluid in addition to the standard ‘normal’ gas fluid. The CGSM tracks the total mass density and bulk momentum of unresolved cold gas, deriving the properties of its unresolved cloudlets from the resolved gas phase. The interactions between the subgrid cold fluid and the resolved fluid are modelled by prescriptions from high-resolution simulations of ‘cloud crushing’ and thermal instability. Through a series of idealized tests, we demonstrate the CGSM’s ability to overcome the resolution limitations of traditional hydrodynamics simulations, successfully capturing the correct cold gas mass, its spatial distribution, and the time-scales for cloud destruction and growth. We discuss the implications of using this model in cosmological simulations to more accurately represent the microphysics that govern the galactic baryon cycle.

Effect of media components on hyperhydricity in horticultural crops: A review

Effect of media components on hyperhydricity in horticultural crops: A review

Standardization of Assay Method of Urease Activity in Inceptisol

Urea is the most important nitrogen fertilizer widely used in crop production and its fate in soils is regulated largely by the soil enzyme urease. The use of precise assay method for urease is an important aspect in regulating activity of soil urease which is the most useful to improve use efficiency of urea, and minimize the problems related to use of urea. In this context, the present laboratory investigation was undertaken with the objective to standardize the assay media components of soil urease activity in Inceptisol of MPKV, Rahuri soils. The Typic Haplustept was selected as a representative of Inceptisol and used for present study of optimizing assay media components for in vivo assay method for measuring activity of urease from Inceptisol. All the assay components viz., substrate concentration (0.2 M), buffer strength (0.05 M), weight of soil (5 g), amount of toluene (0.2 ml) and incubation time (2 h) were found optimum as per Tabatabai and Bremner (1972) except THAM buffer pH. The THAM buffer with a pH 8.5 was found to be optimum for measuring the activity of urease from Inceptisol. The values of urease activity from the 2g weight of soil and 1 h incubation time also found statistically at par with values of 5 g weight of soil and 2 h incubation time, respectively. Hence, the use of 2 g soil and 1 h incubation time in assay procedure are also sufficient for measuring urease activity, if the soil sample size and time are limiting factors.

Optimization of fermentation conditions for 3-methylthio-1-propanol production by Saccharomycopsis fibuligera Y1402 in tobacco matrix

3-methylthio-1-propanol (3-Met) is widely used as a flavoring substance in food flavoring. In this study, the fermentation conditions of Saccharomycopsis fibuligera Y1402 for 3-Met production were optimized in the tobacco matrix. Firstly, the optimization of the culture medium components and culture conditions was carried out through a single factor design. Then, a Plackett-Burman design was used to screen out factors that most significantly affected the production of 3-Met by S. fibuligera Y1402. The steepest ascending path design was used to identify the most significant response region. The optimal conditions for the production of 3-Met were determined using the Box-Behnken experimental design and response surface analysis. These conditions included a particle size of tobacco between 60 and 80 mesh, ammonium sulphate as the nitrogen source with a concentration of 2.4 g/L, L-methionine (L-Met) concentration of 3.1 g/L in the nutrient solution, an incubation time of 145 h, a moisture content of 83%, an initial pH of 5.5, a temperature of 29 °C, and an inoculation size of 1.6%. Under these conditions, the production of 3-Met reached 342.07 mg/g of tobacco. When the culture was scaled up, the conversion yield of 3-Met reached 1.07 g/g of tobacco. This suggests that fermenting this strain can increase the amount of 3-Met in tobacco leaves. This research offers a reference value for employing this strain to enhance the flavor components of crushed tobacco leaves, low-quality tobacco leaves, or tobacco stems, facilitating the processing of inferior tobacco leaves.

Gene editing technology combined with response surface optimization to improve the synthesis ability of lycopene in Pantoea dispersa MSC14.

The aim of this study is to engineer Pantoea dispersa MSC14 into a strain capable of producing lycopene and to enhance its lycopene content. Our laboratory isolated the strain P. dispersa MSC14 from petroleum-contaminated soil in a mining area. Whole-genome sequencing confirmed the existence of a carotenoid synthesis pathway in this strain. This study employed an optimized CRISPR/Cas9 system to perform a traceless gene knockout of the lycopene cyclase gene crtY and to overexpress the octahydrolycopene dehydrogenase gene crtI in the P. dispersa MSC14. This strategic genetic modification successfully constructed the lycopene-producing strain MSC14-LY, which exhibited a notable lycopene content with a biomass productivity of 553μg of lycopene per gram dry cell weight (DCW). Additionally, the components of the lycopene fermentation medium were optimized using Plackett-Burman design and response surface methodology. The average lycopene content was increased to 5.13mg g -1 DCW in the optimized LY fermentation medium. Through genetic engineering, P. dispersa MSC14 was transformed into a strain capable of producing lycopene, achieving a yield of 5.13mg g-1 DCW after medium optimization. Genetic engineering successfully transformed P. dispersa MSC14 into a strain capable of producing lycopene, achieving a yield of 5.13mg g-1 DCW after medium optimization.

Metabolic modelling as a powerful tool to identify critical components of Pneumocystis growth medium.

Establishing suitable in vitro culture conditions for microorganisms is crucial for dissecting their biology and empowering potential applications. However, a significant number of bacterial and fungal species, including Pneumocystis jirovecii, remain unculturable, hampering research efforts. P. jirovecii is a deadly pathogen of humans that causes life-threatening pneumonia in immunocompromised individuals and transplant patients. Despite the major impact of Pneumocystis on human health, limited progress has been made in dissecting the pathobiology of this fungus. This is largely due to the fact that its experimental dissection has been constrained by the inability to culture the organism in vitro. We present a comprehensive in silico genome-scale metabolic model of Pneumocystis growth and metabolism, to identify metabolic requirements and imbalances that hinder growth in vitro. We utilise recently published genome data and available information in the literature as well as bioinformatics and software tools to develop and validate the model. In addition, we employ relaxed Flux Balance Analysis and Reinforcement Learning approaches to make predictions regarding metabolic fluxes and to identify critical components of the Pneumocystis growth medium. Our findings offer insights into the biology of Pneumocystis and provide a novel strategy to overcome the longstanding challenge of culturing this pathogen in vitro.

YouTube channel as a component of convergent media: role, influence and perspectives

The article aims to analyze the role of local media in shaping the public agenda during large-scale military actions in Ukraine and how to increase audience loyalty and engagement through convergent practices. In particular, the content, growth dynamics, target audience characteristics, and specific features of the YouTube channel Dnipro TV as a convergent media are considered. The city television channel has successfully transformed from a traditional broadcaster into a convergent media through its YouTube channel and other social networks. This has allowed it to expand its audience, maintain influence, and adapt to changes in the media landscape. It is noted that during two years of full-scale aggression, the number of subscribers to the Dnipro TV YouTube channel has nearly tripled. The channel hosts all the content produced by the creative team of Dnipro TV. The videos can be accessed directly from the YouTube page or via the respective section on the website. The chosen research period is characterized by, on the one hand, increased demand for local content from the city's TV channel audience due to the hostilities and security threats to the population. On the other hand, there is the involvement of the global community in events in Ukraine and the interest of displaced persons, with local content on the YouTube channel being accessible from any country. Thus, only 64.7 % of users watch videos on the YouTube channel from within Ukraine, while over 35 % view local content from other countries. The analysis also highlights changes in the audience's gender composition: before the war, women constituted the majority, while in 2023 and 2024, the male audience made up 54 %, compared to 45.9 % female. The convergent local media Dnipro TV attracts its audience with news broadcasts, a series of original programs, and talk shows, all of which can be found on YouTube and watched at a convenient time. We believe that the development of this channel as a convergent media with multiplatform content representation holds great promise.