2,3-Butanediol plus acetoin obtention by Enterobacter aerogenes ATCC 13048: inhibition by target products and cells reuse during fed-batch cultivation.

2,3-Butanediol (2,3-BD) is a highly valued building block, and optimizing its production by fermentation, particularly with crude glycerol, is crucial. Enterobacter aerogenes is a key microorganism for this process; however, there are limited studies addressing the inhibition effects of products and by-products on 2,3-BD production. This study investigates these inhibition effects to maximize 2,3-BD production. Final concentrations of 2,3-BD plus acetoin reached 89.3, 92.7, and 71.1 g.L-1 with productivities of 1.22, 1.69, and 0.99 g.L-1.h-1 in pure glycerol, glucose, and crude glycerol media, respectively. Acetic acid was the main by-product, with concentrations ranging from 10 to 15 g.L-1. The reinoculation of E. aerogenes cells highlighted the strong effect of 2,3-BD and acetic acid on microbial growth and metabolism, with the cultivation environment exerting selective pressure. Notably, cells reuse enhanced performance in crude glycerol media, achieving a specific productivity in relation to biomass (YP/X) of 9.18 g.g-1; about 25% higher than in fed-batch without cells reuse. By combining results from two fed-batch cycles, the total final concentration of 2,3-BD plus acetoin reached 99.4 g.L-1, alongside a 33% reduction in total acetic acid production with reused cells.

Streamlined integrated protein isoelectric focusing using microfluidic paper-based device.

An innovative integrated paper-based microdevice was developed for protein separation by isoelectric focusing (IEF), allowing for robust design thanks to a 3D-printed holder integrating separation channel, reservoirs, and electrodes. To reach robustness and precision, the optimization focused on the holder geometry, the paper nature, the reservoir design, the IEF medium, and various focusing parameters. A well-established and stable pH gradient was obtained on a glass-fiber paper substrate with simple sponge reservoirs, and the integration of the electrodes in the holder led to a straightforward system. The separation medium composed of water/glycerol (85/15, v/v) allowed for reducing medium evaporation while being an efficient medium for most hydrophobic and hydrophilic proteins, compatible with mass spectrometry detection for further proteomics developments. To our knowledge, this is the first report of the use of glycerol solutions as a separation medium in a paper-based microdevice. Analytical performances regarding pH gradient generation, pI determination, separation efficiency, and resolution were estimated while varying the IEF experimental parameters. The overall process led to an efficient separation within 25 min. Then, this methodology was applied to a sample composed of saliva doped with proteins. A minimal matrix effect was evidenced, underscoring the practical viability of our platform. This low-cost, versatile and robust paper-based IEF microdevice opens the way to various applications, ranging from sample pre-treatment to integration in an overall proteomic-on-a-chip device.

Selective oxidation of glycerol mediated by surface plasmon of gold nanoparticles deposited on titanium dioxide nanowires.

This paper describes an alternative method for the in situ synthesis of gold nanoparticles (AuNPs) with a particle size of less than 3 nm, using nanoreactors formed by reverse micelles of 1,4-bis-(2-ethylhexyl) sulfosuccinate sodium (AOT) and nanoparticle stabilization with l-cysteine, which favor the preparation of nanoparticles with size and shape control, which are homogeneously dispersed (1% by weight) on the support of titanium dioxide nanowires (TNWs). To study the activity and selectivity of the prepared catalyst (AuNPs@TNWs), an aqueous solution of 40 mM glycerol was irradiated with a green laser (λ = 530 nm, power = 100 mW) in the presence of the catalyst and O2 as an oxidant at 22 °C for 6 h, obtaining a glycerol conversion of 86% with a selectivity towards hydroxypyruvic acid (HA) of more than 90%. From the control and reactions, we concluded that the Ti-OH groups promote the glycerol adsorption on the nanowires surface and the surface plasmon of the gold nanoparticles favors the selectivity of the reaction towards the hydroxypyruvic acid.

Effect of glycerol on properties of chitosan/chlorhexidine membranes and antibacterial activity against Streptococcus mutans.

Introduction: Chitosan membranes with glycerol can function as an effective dispersing agent for different antibiotics or active ingredients that can be used in the treatment of diseases present in the oral cavity. Methods: The effects of the addition of glycerol on the mechanical, water absorption, swelling, pH, thickness, disintegration, rugosity, and antibacterial properties of chitosan-chlorhexidine- glycerol membranes were investigated in this study. Results and discussion: Mechanical results indicated that chitosan membranes' rugosity, strength, flexion, and thickness differed at loading 1, 3, 5, 10, 15, and 20% of glycerol (p < 0.05). The chitosan membranes' rugosity, dissolution, strength, and pH results were significantly enhanced by the presence of glycerol at 3, 5, and 10% concentrations. In this investigation, the antimicrobial activity model used was the inhibition of Streptococcus mutans CDBB-B-1455 by chitosan-chlorhexidine membranes. It was observed that there was no change in inhibition with different concentrations of glycerol. The results suggest that chitosan-glycerol-chlorhexidine membranes may be a potential candidate for topical antiseptic application in buccal-dental disorders caused by S. mutans, such as caries, periodontal diseases, and oral squamous cell carcinoma, helping to prevent the development of serious conditions that can compromise human health.

Transcriptional and Post-Translational Roles of Calcineurin in Cationic Stress and Glycerol Biosynthesis in Cryptococcus neoformans.

Stress management is an adaptive advantage for survival in adverse environments. Pathogens face this challenge during host colonization, requiring an appropriate stress response to establish infection. The fungal pathogen Cryptococcus neoformans undergoes thermal, oxidative, and osmotic stresses in the environment and animal host. Signaling systems controlled by Ras1, Hog1, and calcineurin respond to high temperatures and osmotic stress. Cationic stress caused by Na+, K+, and Li+ can be overcome with glycerol, the preferred osmolyte. Deleting the glycerol phosphate phosphatase gene (GPP2) prevents cells from accumulating glycerol due to a block in the last step of its biosynthetic pathway. Gpp2 accumulates in a phosphorylated form in a cna1Δ strain, and a physical interaction between Gpp2 and Cna1 was found; moreover, the gpp2Δ strain undergoes slow growth and has attenuated virulence in animal models of infection. We provide biochemical evidence that growth in 1 M NaCl increases glycerol content in the wild type, whereas gpp2Δ, cna1Δ, and cnb1Δ mutants fail to accumulate it. The deletion of cnb1Δ or cna1Δ renders yeast cells sensitive to cationic stress, and the Gfp-Gpp2 protein assumes an abnormal localization. We suggest a mechanism in which calcineurin controls Gpp2 at the post-translational level, affecting its localization and activity, leading to glycerol biosynthesis. Also, we showed the transcriptional profile of glycerol-deficient mutants and established the cationic stress response mediated by calcineurin; among the biological processes differentially expressed are carbon utilization, translation, transmembrane transport, glutathione metabolism, oxidative stress response, and transcription regulation. To our knowledge, this is the first time that this transcriptional profile has been described. These results have implications for pathogen stress adaptability.

Development of New Edible Biodegradable Films Containing Camu-Camu and Agro-Industry Residue.

The use of edible films has garnered significant interest in the food and environmental sectors due to their potential to prevent food deterioration and their biodegradability. This study aimed to develop and characterize edible films based on camu-camu residue, gelatin, and glycerol, evaluating their solubility, thermal, degradability, antioxidant, and water vapor permeability properties of the gelatin matrix. This is the first study incorporating camu-camu into a gelatin and glycerol matrix. The films produced with camu-camu residue were manageable and soluble, with some non-soluble residues, providing a shiny and well-presented appearance. In the biodegradation results, samples 3 and 4 appeared to degrade the most, being two of the three most affected samples in the triplicate. The films showed degradation modifications from the third day of the experiment. In the germination and plant growth analysis, sample 4 exhibited satisfactory development compared to the other samples, emerging as the sample with the best overall result in the analyses, attributed to a 13.84 cm increase in the growth of the upper part of the seedling. These results indicate that the produced materials have potential for food packaging applications.

Clarifying Glycerol Electrooxidation Studies on Pd-Based Catalysts: Insights Into Catalytic Performance and Practical Challenges.

Escalating biodiesel production led to a surplus of glycerol, prompting its exploration as a valuable resource in industrial applications. Electrochemical systems have been studied, specifically employing noble metal catalysts like palladium for glycerol electrooxidation. Despite numerous studies on Pd-based catalysts for glycerol electrooxidation, a comprehensive analysis addressing critical questions related to the economic feasibility, global sourcing of Pd, and the thematic cohesion of publications in this field is lacking. Moreover, a standardized framework for comparing the results of various studies is absent, hindering progress on glycerol technologies. This critical overview navigates the evolution of Pd-based catalysts for glycerol electrooxidation, examining catalytic activity, stability, and potential applications. It critically addresses the geographical sources of Pd, the motivation behind glycerol technology exploration, thematic coherence in existing publications, and the meaningful comparison of results. It correlates the use of Pd-based catalysts with the natural source of Pd and the origin of glycerol derived from biodiesel. The proposed standardized approach for comparing electrochemical parameters and establishing experimental protocols provides a foundation for meaningful study comparisons. This critical overview underscores the need to address fundamental questions to accelerate the transition of glycerol technologies from laboratories to practical applications.

Isolation, screening, and characterization of the newly isolated osmotolerant yeast Wickerhamomyces anomalus BKK11-4 for the coproduction of glycerol and arabitol.

This study explored the isolation and screening of an osmotolerant yeast, Wickerhamomyces anomalus BKK11-4, which is proficient in utilizing renewable feedstocks for sugar alcohol production. In batch fermentation with high initial glucose concentrations, W. anomalus BKK11-4 exhibited notable production of glycerol and arabitol. The results of the medium optimization experiments revealed that trace elements, such as H3BO3, CuSO4, FeCl3, MnSO4, KI, H4MoNa2O4, and ZnSO4, did not increase glucose consumption or sugar alcohol production but substantially increased cell biomass. Osmotic stress, which was manipulated by varying initial glucose concentrations, influenced metabolic outcomes. Elevated glucose levels promoted glycerol and arabitol production while decreasing citric acid production. Agitation rates significantly impacted the kinetics, enhancing glucose utilization and metabolite production rates, particularly for glycerol, arabitol, and citric acid. The operational pH dictated the distribution of the end metabolites, with glycerol production slightly reduced at pH 6, while arabitol production remained unaffected. Citric acid production was observed at pH 6 and 7, and acetic acid production was observed at pH 7. Metabolomic analysis using GC/MS identified 29 metabolites, emphasizing the abundance of sugar/sugar alcohols. Heatmaps were generated to depict the variations in metabolite levels under different osmotic stress conditions, highlighting the intricate metabolic dynamics occurring post-glucose uptake, affecting pathways such as the pentose phosphate pathway and glycerolipid metabolism. These insights contribute to the optimization of W. anomalus BKK11-4 as a whole-cell factory for desirable products, demonstrating its potential applicability in sustainable sugar alcohol production from renewable feedstocks.

Towards the valorisation of glycerol by designing the surface chemistry of carbon xerogels by doping and oxygen functionalization.

Research on innovative approaches to the valorisation of glycerol as a subproduct of biodiesel production has acquired an increasing demand in the development of a circular economy around energy generation, especially, in the line of improvement of the heterogeneous metallic catalysts used. In this regard, carbon xerogels have gained importance due to their stability and modifiability, while transition metals such as copper stand out as a cost-effective alternative, resulting in a technology where surface engineering plays a crucial role in achieving competitive catalytic activity. Building upon this, current research evaluates doped xerogels (Si, N, or GO) as supports of Cu and catalysts by themselves for glycerol oxidation. Benefits from the incorporation of oxygenated functional groups (OFG) were also evaluated. Results showed a consistently higher selectivity towards lactic acid (LA) across all catalysts and competitive catalytic conversion. In this performance, dopants played a crucial role in surface acid-base characteristics, while oxygenated functional groups (OFG) influenced copper adsorption, dispersion, and reducibility. Notably, the Cu/CXN-f catalyst demonstrated the highest LA yield by combining the effect of N as a doping species, with the presence of OFG and the formation of appropriated metallic Cu domains. This research underscores the potential of carbon xerogels in the tailored catalyst design, contributing to sustainable chemical production through their customizable textural and chemical properties.

Unveiling the formation capacity of multicomponent oleogels: Performance of lecithin interacting with monostearate derivatives.

Oleogels have been explored as fat substitutes due to their healthier composition compared to trans and saturated fats, also presenting interesting technological perspectives. The aim of this study was to investigate the compositional perspective of multicomponent oleogels. Structuring ability of lecithin (LEC) (20 or 90 wt% of phosphatidylcholine - PC) combined with glycerol monostearate (GMS), sorbitan monostearate (SMS) or sucrose monostearate (SAC) in sunflower oil was evaluated from oleogels properties. The thermal and rheological properties, microstructure and stability of the oleogels were affected by the difference in the chemical composition of LEC and the ratio between LEC and different surfactants. Interestingly, low-phosphatidylcholine LEC (L20) performed better, although systems formed with reduced amounts of LEC tended to be softer (LEC-GMS) and present high oil holding capacity (LEC-SMS). The mixtures of LEC and monostearate-based surfactants showed different behaviors, depending on the surfactant polar head. In LEC-GMS systems, LEC hindered the self-assembly of GMS in sunflower oil, compromising mechanical properties and increasing oil release. When combined with SMS, LEC acted as a crystal habit modifier of SMS, forming a more homogeneous microstructure and producing stronger oleogels with greater oil binding capacity. However, above the threshold concentration, LEC prevented SMS self-assembly, resulting in a weaker gel. A positive interaction was found in LEC-SAC formulations in specific ratios, since SAC cannot act as a single oleogelator. Results show the impact of solubility balance played by LEC and fatty-acid derivatives surfactant when combined and used as oleogelators. This knowledge can contribute to a rational perspective in the preparation and modulation of the properties of edible oleogels.

Glycerol Electrolyzer with Graphite Anode and Cathode Produces Carbonyl Compounds and Hydrogen: Background Electrocatalysis of a "Nonparticipating" Current Collector.

This study unveils a novel role of bare graphite as a catalyst in glycerol electrooxidation and hydrogen evolution reactions, challenging the prevailing notion that current collectors employed in electrolyzers are inert. Half-cell experiments elucidate the feasibility of glycerol oxidation and hydrogen production on bulk graphite electrodes at potentials exceeding 1.7 V. The investigation of varying glycerol concentrations (0.05 to 1.5 mol L-1) highlights a concentration-dependent competition between glycerol electrooxidation and oxygen evolution reactions. Employing an H-type glycerol electrolyzer, polarization curves reveal significant activation polarization attributed to the low electroactivity of the anode. Glycerol electrolysis at different concentrations yields diverse product mixtures, including formate, glycolate, glycerate, and lactate at the anode, with concurrent hydrogen generation at the cathode. The anolyte composition changes with glycerol concentration, resulting in less-oxidized compounds at higher concentrations and more oxidized compounds at lower concentrations. The cell voltage also influences the product formation selectivity, with an increased voltage favoring more oxidized compounds. The glycerol concentration also affects hydrogen production, with lower concentrations yielding higher hydrogen amounts, peaking at 3.5 V for 0.05 mol L-1. This model quantitatively illustrates graphite's contribution to current and product generation in glycerol electrolyzers, emphasizing the significance of background current and products originating from current collectors if in contact with the reactants. These results have an impact on the efficiency of the electrolyzer and raise questions regarding possible extra non-noble "nonparticipating" current collectors that could affect overall performance. This research expands our understanding of electrocatalysis on graphite surfaces with potential applications in optimizing electrolyzer configurations for enhanced efficiency and product selectivity.

Mathematical-Physical description of the oxygen-inhibited layer (OIL) in nanofilled dental polymers / Descripción físico-matemática de la capa inhibida por oxígeno en polímeros dentales nano rellenados

Abstract This research evaluates the presence of the oxygen-inhibited layer (OIL) on the top surface of a photopolymerized dental composite resin protected with a glycerin layer. This evaluation was conducted using physical and mathematical methods. Polymerized discs were fabricated to evaluate Vickers microhardness (VHN), and pre-and post-polymerized samples were used for the calculation of C-O/C-H ratios through Fourier Transform Infrared Spectroscopy (FTIR) (n=10), using two types of glycerin, one for medical use (MG) and another for dental use (DG). Surface hardness decreased from MG to DG to CO, and the increase in C-O/C-H ratios decreased in the same order (p<0.05). Samples protected with medical and dental glycerin layers are harder and exhibit lower C-O/C-H bond ratios than the control group.

Resumen La presente investigación evalúa la presencia de la capa inhibida por oxígeno OIL en la última superficie fotocurada de una resina compuesta de uso odontológica que fue protegida con una capa de glicerina. Esta evaluación se hizo a partir de métodos físicos y matemáticos. Se fabricaron discos polimerizados para evaluar la microdureza Vickers (VHN) y pre y post polimerizados para el cálculo de tasas C-O/C-H por medio de Espectroscopía Infrarroja Transformada de Fourier (FTIR) (n=10) usando dos tipos de glicerina, una de uso médico (MG) y otra de uso dental (DG). La dureza superficial disminuyó de MG a DG a CO y el aumento de tasas C-O/C-H disminuyó en ese mismo orden (p<0,05). Las muestras protegidas con capas de glicerina médica y odontológica son más duras y presentan menos cantidad tasas de enlaces C-O/C-H que el grupo control.

An Integrated Process Analysis for Producing Glycerol Carbonate from CO2 and Glycerol.

Glycerol carbonate (GC) is one of the most attractive green chemicals involved in several applications such as polymer synthesis, e. g., the production of polyurethanes and polycarbonates. This relevant chemical can be produced, in a green way, using CO2 (from carbon capture) and glycerol (a byproduct from biodiesel manufacturing). Therefore, in this work, a comprehensive analysis of the GC production process is conducted based on the following synthesis route: urea-dimethyl carbonate-GC using carbon dioxide and glycerol as the main raw materials where the synthesis pathway was efficiently integrated using Aspen Plus. A techno-economic analysis was performed in order to estimate the required capital investment and operating cost for the whole GC process, providing insights on individual capital cost requirements for the urea, dimethyl carbonate, and GC production sections. A total capital cost of $192.1 MM, and a total operating cost of $225.7 MM/y were estimated for the process. The total annualized cost was estimated as $1,558 USD/t of GC produced, competitive with current market price.

Polymeric films of corn starch enhance the lethal effects of thymol and carvacrol terpenes upon Rhipicephalus microplus ticks.

The tick Rhipicephalus microplus is a parasite of great importance in cattle breeding. It is responsible for huge economic losses. The application of synthetic acaricides is used as a form of control. However, resistant strains have been selected over the years, making it necessary to search for new alternative formulations. The present study aimed to formulate biodegradable films impregnated with the terpenes carvacrol and thymol and evaluate their efficacy on larvae and adults of R. microplus through in vitro tests. The following formulations were prepared: Film 1 (starch based); Film 2 (based on starch and glycerol); Film 1 + Carvarcol or Thymol; Film 2 + Carvarcol or Thymol. Terpenes had a final concentration of 5.0 mg/mL. To evaluate the formulations on larvae, the immersion test was performed by dividing into six groups according to the concentration of terpenes: 5.0, 2.5, 1.25, 0.625, 0.313, 0.156 mg/mL and the control groups: 1% ethanol solution; 10% ethanol solution; Film 1; and Film 2. For the evaluations on adult ticks, ten experimental groups (n = 10) were used: 1) Carvacrol; 2) Film 1 + Carvacrol; 3) Film 2 + Carvacrol; 4) Thymol; 5) Film 1 + Thymol; 6) Film 2 + Thymol; 7) Distilled water; 8) 10% ethanol solution; 9) Film 1; and 10) Film 2. In experimental groups 1-6, carvacrol and thymol (free or incorporated in two different biodegradable film formulations) were evaluated at the same concentration (5.0 mg/mL). Each group of ticks was immersed in their respective solutions for five minutes. The results of the tests on larvae showed that the Film 1 + thymol and Film 2 + carvacrol formulations had the lowest lethal concentrations (0.076 and 0.255 mg/mL, respectively), values up to 9.0-fold lower than the monoterpenes tested outside the formulation. Carvacrol and thymol at the concentrations tested were effective in controlling engorged females with a percentage of 32.2% and 63.8%, respectively. When incorporated into biodegradable film formulations, these monoterpenes showed much greater efficacy. Film 1 + carvacrol and Film 2 + carvacrol with control percentages of 71.6% and 97.2%, respectively, while the formulations Film 1 + thymol and Film 2 + thymol showed values of 96.9% and 100.0%. The tick control activity of the biopolymer formulations with thymol and carvacrol was demonstrated through the high mortality rates of larvae and engorged females of the tick R. microplus. Therefore, the results obtained indicate that these formulations have great potential for tick control mainly because of the percentage of control up to 100% in engorged females in in vitro tests.

Physiological characterization of polyextremotolerant yeasts from cold environments of Patagonia.

Yeasts from cold environments have a wide range of strategies to prevent the negative effects of extreme conditions, including the production of metabolites of biotechnological interest. We investigated the growth profile and production of metabolites in yeast species isolated from cold environments. Thirty-eight strains were tested for their ability to grow at different temperatures (5-30 °C) and solute concentrations (3-12.5% NaCl and 50% glucose). All strains tested were able to grow at 5 °C, and 77% were able to grow with 5% NaCl at 18 °C. We were able to group strains based on different physicochemical/lifestyle profiles such as polyextremotolerant, osmotolerant, psychrotolerant, or psychrophilic. Five strains were selected to study biomass and metabolite production (glycerol, trehalose, ergosterol, and mycosporines). These analyses revealed that the accumulation pattern of trehalose and ergosterol was related to each lifestyle profile. Also, our findings would suggest that mycosporines does not have a role as an osmolyte. Non-conventional fermentative yeasts such as Phaffia tasmanica and Saccharomyces eubayanus may be of interest for trehalose production. This work contributes to the knowledge of non-conventional yeasts with biotechnological application from cold environments, including their growth profile, metabolites, and biomass production under different conditions.

Increasing the Pentose Phosphate Pathway Flux to Improve Plasmid DNA Production in Engineered E. coli.

The demand of plasmid DNA (pDNA) as a key element for gene therapy products, as well as mRNA and DNA vaccines, is increasing together with the need for more efficient production processes. An engineered E. coli strain lacking the phosphotransferase system and the pyruvate kinase A gene has been shown to produce more pDNA than its parental strain. With the aim of improving pDNA production in the engineered strain, several strategies to increase the flux to the pentose phosphate pathway (PPP) were evaluated. The simultaneous consumption of glucose and glycerol was a simple way to increase the growth rate, pDNA production rate, and supercoiled fraction (SCF). The overexpression of key genes from the PPP also improved pDNA production in glucose, but not in mixtures of glucose and glycerol. Particularly, the gene coding for the glucose 6-phosphate dehydrogenase (G6PDH) strongly improved the SCF, growth rate, and pDNA production rate. A linear relationship between the G6PDH activity and pDNA yield was found. A higher flux through the PPP was confirmed by flux balance analysis, which also estimates relevant differences in fluxes of the tricarboxylic acid cycle. These results are useful for developing further cell engineering strategies to increase pDNA production and quality.

Nanoparticulated WO3/NiWO4 Using Cellulose as a Template and Its Application as an Auxiliary Co-Catalyst to Pt for Ethanol and Glycerol Electro-Oxidation.

This work reports the use of cellulose as a template to prepare nanosized WO3 or NiWO4 and its application as a co-catalyst in the electro-oxidation of ethanol and glycerol. Microcrystalline cellulose was hydrolyzed with phosphotungstic acid (H3PW12O40) to prepare the nanocrystalline cellulose template. The latter was air-calcinated to remove the template and obtain nanometric WO3. Tungsten oxide was impregnated with Ni(NO3)2, which was subsequently air-calcinated to obtain the nanometric NiWO4. Elemental analysis confirmed the coexistence of nickel and tungsten, whereas thermal analysis evidenced a high thermal stability for these materials. The X-ray diffractograms displayed crystal facets of WO3 and, when Ni(II) was added, NiWO4. The transmission electron micrographs corroborated the formation of nanosized particles with average particle sizes in the range of 30 to 50 nm. Finally, to apply this material, Pt/WO3-C and Pt/WO3-NiWO4-C were prepared and used in ethanol and glycerol electro-oxidation in an alkaline medium, observing a promotional effect of the oxide and tungstate by reducing the onset potential and increasing the current density. These materials show great potential to produce clean electricity or green hydrogen, contributing to energetic transition.

Glycerol as substrate and NADP+-dependent glyceraldehyde-3-phosphate dehydrogenase enable higher production of 3-hydroxypropionic acid through the ß-alanine pathway in E. coli.

Microbial engineering is a promising way to produce3-HP using biorenewable substrates such as glycerol. However, theglycerol pathway to obtain 3-HPrequires vitamin B-12, which hinders its economic viability. The present work showed that 3-HP can be efficiently produced from glycerol through the ß-alanine pathway. To develop a cell factory for this purpose, glycerol was evaluated as a substrate and showed more than two-fold improved 3-HP production compared to glucose. Next, the reducing power was modulated by overexpression of an NADP+ -dependent glyceraldehyde-3-phosphate dehydrogenase coupled with CRISPR-based repression of the endogenous gapA gene, resulting in a 91 % increase in 3-HP titer. Finally, the toxicity of 3-HP accumulation was addressed by overexpressing a putative exporter (YohJK). Fed-batch cultivation of the final strain yielded 72.2 g/L of 3-HP and a productivity of 1.64 g/L/h, which are the best results for the ß-alanine pathway and are similar to those found for other pathways.

Optimizing biodegradable plastics: Molecular dynamics insights into starch plasticization with glycerol and oleic acid.

Petroleum-based plastics dominate everyday life, necessitating the exploration of natural polymers as alternatives. Starch, abundant and biodegradable, is a promising raw material. However, understanding the molecular mechanisms underlying starch plasticization has proven challenging. To address this, we employ molecular dynamics simulations, focusing on amylose as a model. Our comprehensive evaluation revealed that chain size affects solubility, temperature influenced diffusivity and elastic properties, and oleic acid expressed potential as an alternative plasticizer. Furthermore, blending glycerol or oleic acid with water suggested the enhancement amylose's elasticity. These findings contribute to the design of sustainable and improved biodegradable plastics.

Use of a one-step freezing protocol for boar sperm with distinct cryoprotectants / Protocolo de congelamento one-step para sêmen suíno utilizando diferentes crioprotetores

The present study evaluated the cryoprotectant efficacy of dimethylacetamide (DMA) and ethylene glycol in a one-step protocol to freeze boar sperm. The sperm-rich portion of the ejaculates from two boars were collected once a week, for 10 weeks. After collection, the ejaculates were diluted (1:1; v/v) in the cooling extender. After determining their spermatozoa concentration, the ejaculates were pooled with the same number of spermatozoa from each boar and stabilized at 20°C for 120 min. Distinct cryoprotectants were added to the cooling extender at 20 °C, at different concentrations, composing six treatments: 1.25% and 2.5% glycerol (control); 1.25% and 2.5% ethylene glycol; 2.5% and 5.0% DMA. The samples were stored in 0.25 mL straws, containing 35 × 106 spermatozoa. After 90 min at 20 °C, the straws were submitted to a cooling curve until 5 °C (0.3 to 0.5 °C/min) and kept at 5°C for 60 min. Freezing was conducted by placing the straws horizontally 5 cm above the liquid nitrogen for 10 min, followed by immersion on liquid nitrogen. After thawing at 37 °C for 30 seconds, sperm quality was evaluated through a computer-assisted semen analysis system and flow cytometry. Sperm motility was greater (P< 0.05) in treatments with 5.0% and 2.5% DMA (22.2 ± 2.6% and 20.0 ± 2.8%, respectively) than in treatment with 2.5% ethylene glycol (8.2 ± 1.0%). The integrity of the plasma membrane (P = 0.08) and mitochondrial membrane potential (P = 0.27) was similar among the treatments. The treatment with 2.5% ethylene glycol was the least efficient to maintain intact acrosome membrane (P< 0.01). Some kinetics parameters (DAP, DCL, DSL, VAP, VCL, VSL e ALH) were positively affected by 5.0% DMA. The one-step freezing protocol resulted in unsatisfactory boar sperm motility after thawing, regardless of the cryoprotectant.

O presente estudo objetivou avaliar a eficácia de um protocolo one-step de congelamento do sêmen suíno utilizando dimetilacetamida (DMA) e etilenoglicol como crioprotetores. Durante 10 semanas, a fração rica dos ejaculados de dois machos suínos foram coletados, uma vez por semana. Após a coleta, os ejaculados foram diluídos (1:1; v/v) no diluidor de resfriamento. Após a avaliação da concentração espermática, os ejaculados foram agrupados em um pool com o mesmo número de espermatozoides de cada macho e estabilizados a 20 °C por 120 min. Os criopropetores foram adicionados ao diluidor de congelamento a 20 °C, em diferentes concentrações, compondo seis tratamentos: glicerol (controle), 1,25% e 2,5%; etilenoglicol, 1,5% e 2,5%; e DMA, 2,5% e 5,0%. As amostras foram armazendadas em palhetas de 0,25 mL contendo 35 x 106 espermatozoides. Após 90 min a 20 °C as palhetas foram submetidas a uma curva de resfriamento até 5 °C (0,3 a 0,5 °C/mim) e mantidas a 5 °C por 60 min. O congelamento foi realizado a partir da colocação das palhetas horizontalmente a 5 cm acima do nitrogênio líquido por 10 min, com sua posterior imersão no nitrogênio líquido. Após o descongelamento a 37 °C por 30 segundos a qualidade espermática foi avaliada através de um sistema computadorizado e por citometria de fluxo. A motilidade espermática foi maior (P < 0,05) nos tratamentos com 5,0% e 2,5% DMA (22,2 ± 2,6% e 20,0 ± 2,8%, respectivamente) do que no tratamento com 2,5% etilenoglicol (8,2 ± 1,0%). A integridade da membrana plasmática (P = 0,08) e potencial de membrana mitocondrial (P = 0,27) foi similar entre os tratamentos. O tratamento com 2,5% de etilenoglicol foi menos eficiente em manter membrana acrossomal intacta (P< 0,01). Alguns parâmetros de cinética espermática (DAP, DCL, DSL, VAP, VCL, VSL e ALH) foram afetados positivamente pelo uso de DMA a 5.0%. O protocolo simplificado para congelamento de sêmen suíno resultou em motilidade espermática insatifatória após o descongelamento, independente do crioprotetor utilizado.