Enhanced antifungal properties of poly(butylene succinate) film with lignin nanoparticles and trans-cinnamaldehyde for mango packaging.

Sustainable poly(butylene succinate) (PBS) films incorporating lignin nanoparticles (LN) and trans-cinnamaldehyde (CN) have been developed to preserve mango freshness and provide food safety. PBS/LN, PBS/CN, and PBS/LN/CN composite films were produced by blown film melt extrusion. This study investigated the effect of CN-LN on the CN remaining content, thermal, mechanical, and barrier properties, diffusion coefficient, and antifungal activity of PBS films both in vitro and in vivo. Results showed that LN in the PBS/LN/CN composite film contained more CN than in the PBS/CN film. The compatibility of CN-LN with PBS produced homogeneous surfaces with enhanced barrier properties. PBS/LN/CN composite films demonstrated superior antifungal efficacy, inhibiting the growth of Colletotrichum gloeosporioides and preserving mango quality during storage. Results suggested that incorporating LN into PBS composite films prolonged the sustained release of antifungal agents, thereby inhibiting microbial growth and extending the shelf life of mangoes. Development of PBS/LN/CN composite films is a beneficial step toward reducing food waste and enhancing food safety.

A highly biocompatible CE-crosslinked collagen implant with exceptional anti-calcification and collagen regeneration capabilities for aging skin rejuvenation.

Skin aging, a complex and inevitable biological process, results in wrinkles, dermal laxity, and skin cancer, profoundly influencing appearance and overall health. Collagen serves as the fundamental element of the dermal matrix; nevertheless, collagen is susceptible to enzymatic degradation within the body. Crosslinking is employed to enhance the physicochemical properties of collagen. However, conventional crosslinking agents may harbor potential issues such as cytotoxicity and calcification risks, constraining their application in the biomedical field. Therefore, we have for the first time developed a highly biocompatible CE-crosslinked collagen implant with exceptional anti-calcification and collagen regeneration capabilities for aging skin rejuvenation. A novel collagen crosslinking agent (CE) was synthesized through a reaction involving chitosan quaternary ammonium salt with 1,4-butanediol diglycidyl ether. Compared to collagen crosslinked with glutaraldehyde (GA), the CE-crosslinked collagen implant exhibited notable stability and durability. The implant demonstrated excellent injectability and viscosity, resisting displacement after implantation. Additionally, the CE-crosslinked collagen implant displayed superior biocompatibility, effectively promoting the proliferation and adhesion of HFF-1 cells compared with the GA-crosslinked collagen. The CE-crosslinked collagen represented a safer and more biologically active implant material. In vivo experiments further substantiated that the implant significantly facilitated collagen regeneration without inducing calcification. The innovative collagen implant has made substantial strides in enhancing aesthetics and reducing wrinkles, presenting the potential for revolutionary progress in the fields of skin rejuvenation and collagen regeneration.

Anti-inflammatory effect of lignans from flaxseed after fermentation by lactiplantibacillus plantarum SCB0151 in vitro.

Lignan, a beneficial constituent of Flaxseed (Linum usitatissimum L.) showed great interest in researchers because of its multiple functional properties. Nonetheless, a challenge arises due to the glycosidic structure of lignans, which the gut epithelium cannot readily absorb. Therefore, we screened 18 strains of Lactiplantibacillus plantarum, Lacticaseibacillus casei, Lactobacillus acidophilus, Lacticaseibacillus rhamnosus, Pediococcus pentosaceus, Pediococcus acidilactici, and Enterococcus durans to remove glycosides from flaxseed lignan extract enzymatically. Among our findings, Lactiplantibacillus plantarum SCB0151 showed the highest activity of ß-glucosidase (8.91 ± 0.04 U/mL) and higher transformed efficiency of Secoisolariciresinol (SECO) (8.21 ± 0.13%). The conversion rate of Secoisolariciresinol diglucoside (SDG) and the generation rate of SECO was 58.30 ± 3.78% and 32.13 ± 2.78%, respectively, under the optimized conditions. According to the LC-HRMSMS analysis, SECO (68.55 ± 6.57 µM), Ferulic acid (FA) (32.12 ± 2.50 µM), and Coumaric acid (CA) (79.60 ± 6.21 µM) were identified in the biotransformation products (TP) of flaxseed lignan extract. Results revealed that the TP exhibited a more pronounced anti-inflammatory effect than the flaxseed lignan extract. SECO, FA, and CA demonstrated a more inhibitory effect on NO than that of SDG. The expression of iNOS and COX-2 was significantly suppressed by TP treatment in LPS-induced Raw264.7 cells. The secretion of IL-6, IL-2, and IL-1ß decreased by 87.09 ± 0.99%, 45.40 ± 0.87%, and 53.18 ± 0.83%, respectively, at 60 µg/mL of TP treatment. Given these data, the bioavailability of flaxseed lignan extract and its anti-inflammatory effect were significantly enhanced by Lactiplantibacillus plantarum SCB0151, which provided a novel approach to commercializing flaxseed lignan extract for functional food.

Multiplex Marker-Less Genome Integration in Pichia pastoris Using CRISPR/Cas9.

Pichia pastoris is known for its excellent protein expression ability. As an industrial methyl nutritional yeast, it can effectively utilize methanol as the sole carbon source, serving as a potential platform for C1 biotransformation. Unfortunately, the lack of synthetic biology tools in P. pastoris limits its broad applications, particularly when multigene pathways should be manipulated. Here, the CRISPR/Cas9 system is established to efficiently integrate multiple heterologous genes to construct P. pastoris cell factories. In this protocol, with the 2,3-butanediol (BDO) biosynthetic pathway as a representative example, the procedures to construct P. pastoris cell factories are detailed using the established CRISPR-based multiplex genome integration toolkit, including donor plasmid construction, competent cell preparation and transformation, and transformant verification. The application of the CRISPR toolkit is demonstrated by the construction of engineered P. pastoris for converting methanol to BDO. This lays the foundation for the construction of P. pastoris cell factories harboring multi-gene biosynthetic pathways for the production of high-value compounds.

Unlocking the potentials of Ustilago trichophora for up-cycling polyurethane-derived monomer 1,4-butanediol.

Plastic usage by microbes as a carbon source is a promising strategy to increase the recycling quota. 1,4-butanediol (BDO) is a common monomer derived from polyesters and polyurethanes. In this study, Ustilago trichophora was found to be an efficient cell-factory to valorize BDO. To investigate product formation by U. trichophora, we refined the traditional ion exclusion liquid chromatography method by examining eluent, eluent concentrations, oven temperatures, and organic modifiers to make the chromatography compatible with mass spectrometry. An LC-UV/RI-MS2 method is presented here to identify and quantify extracellular metabolites in the cell cultures. With this method, we successfully identified that U. trichophora secreted malic acid, succinic acid, erythritol, and mannitol into the culture medium. Adaptive laboratory evolution followed by medium optimization significantly improved U. trichophora growth on BDO and especially malic acid production. Overall, the carbon yield on the BDO substrate was approximately 33% malic acid. This study marks the first report of a Ustilaginaceae fungus capable of converting BDO into versatile chemical building blocks. Since U. trichophora is not genetically engineered, it is a promising microbial host to produce malic acid from BDO, thereby contributing to the development of the envisaged sustainable bioeconomy.

Application of MicroResp™ for quick and easy detection of plastic degradation by marine bacterial isolates.

Microplastic debris in the marine environment is a global problem. Biodegradable polymers are being developed as alternatives to petroleum-based plastics, and quick and easy methods for screening for bacterial strains that can degrade such polymers are needed. As a screening method, the clear zone method has been widely used but has technical difficulties such as plate preparation and interpretation of results. In this study, we adapted the MicroResp™ system to easily detect biodegradation activity of marine bacteria in a 3-day assay. Among the 6 bacterial strains tested, 3, 2 and 1 strain degraded poly (butylene succinate-co-adipate) (PBSA), poly (ε-caprolactone) (PCL) and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate), respectively. Only one strain that showed degradation activity of PBSA and PCL in the MicroResp™ system was also positive in the clear zone assay on the respective emulsion plates. Our results show that the adapted MicroResp™ system can screen for bacterial strains that degrade plastic.

Inactivation of hydrogenase-3 leads to enhancement of 1,3-propanediol and 2,3-butanediol production by Klebsiella pneumoniae.

Klebsiella pneumoniae can use glucose or glycerol as carbon sources to produce 1,3-propanediol or 2,3-butanediol, respectively. In the metabolism of Klebsiella pneumoniae, hydrogenase-3 is responsible for H2 production from formic acid, but it is not directly related to the synthesis pathways for 1,3-propanediol and 2,3-butanediol. In the first part of this research, hycEFG, which encodes subunits of the enzyme hydrogenase-3, was knocked out, so K. pneumoniae ΔhycEFG lost the ability to produce H2 during cultivation using glycerol as a carbon source. As a consequence, the concentration of 1,3-propanediol increased and the substrate (glycerol) conversion ratio reached 0.587 mol/mol. Then, K. pneumoniae ΔldhAΔhycEFG was constructed to erase lactic acid synthesis which led to the further increase of 1,3-propanediol concentration. A substrate (glycerol) conversion ratio of 0.628 mol/mol in batch conditions was achieved, which was higher compared to the wild type strain (0.545 mol/mol). Furthermore, since adhE encodes an alcohol dehydrogenase that catalyzes ethanol production from acetaldehyde, K. pneumoniae ΔldhAΔadhEΔhycEFG was constructed to prevent ethanol production. Contrary to expectations, this did not lead to a further increase, but to a decrease in 1,3-propanediol production. In the second part of this research, glucose was used as the carbon source to produce 2,3-butanediol. Knocking out hycEFG had distinct positive effect on 2,3-butanediol production. Especially in K. pneumoniae ΔldhAΔadhEΔhycEFG, a substrate (glucose) conversion ratio of 0.730 mol/mol was reached, which is higher compared to wild type strain (0.504 mol/mol). This work suggests that the inactivation of hydrogenase-3 may have a global effect on the metabolic regulation of K. pneumoniae, leading to the improvement of the production of two industrially important bulk chemicals, 1,3-propanediol and 2,3-butanediol.

A sustainable packaging composite of waste paper and poly(butylene succinate-co-lactate) with high biodegradability.

The challenge of global climate change has drawn people's attention to the issue of carbon emissions. Reducing the use of petroleum-derived materials and increasing the use of biodegradable materials is a current focus of research, especially in the packaging materials industry. This study focused on the use of environmentally friendly plastics and waste paper as the main materials for packaging films. Poly(butylene succinate-co-lactate) (PBSL) was modified with maleic anhydride (MA) to form a biobased compatibilizer (MPBSL), which was then blended with a mixture (WPS) of waste-paper powder (WP) and silica aerogel powder (SP) to form the designed composite (MPBSL/WPS). The modification of PBSL with MA improved interfacial adhesion between PBSL and WPS. The structure, thermal, and mechanical properties, water vapor/oxygen barrier, toxicity, freshness, and biodegradability of MPBSL/WPS films were evaluated. Compared with the PBSL/WP film, the MPBSL/WPS film exhibited increased tensile strength at break of 4-13.5 MPa, increased initial decomposition loss at 5 wt% of 14-35 °C, and decreased water/oxygen permeabilities of 18-105 cm3/m2·d·Pa. In the water absorption test, the MPBSL/WPS film displayed about 2-6 % lower water absorption than that of the PBSL/WP film. In the cytocompatibility test, both MPBSL/WPS and PBSL/WP membrane were nontoxic. In addition, compared with PBSL/WP film and the control, the MPBSL/WPS film significantly reduced moisture loss, extended the shelf life, and prevented microbial growth in vegetable and meat preservation tests. Both MPBSL/WPS and PBSL/WP films were biodegradable in a 60-day soil biodegradation test; the degradation rate was 50 % when the WP or WPS content was 40 wt%. Our findings indicate that the composites would be suitable for environmentally sustainable packaging materials.

Evaluation of enzyme-constrained genome-scale model through metabolic engineering of anaerobic co-production of 2,3-butanediol and glycerol by Saccharomyces cerevisiae.

Enzyme-constrained genome-scale models (ecGEMs) have potential to predict phenotypes in a variety of conditions, such as growth rates or carbon sources. This study investigated if ecGEMs can guide metabolic engineering efforts to swap anaerobic redox-neutral ATP-providing pathways in yeast from alcoholic fermentation to equimolar co-production of 2,3-butanediol and glycerol. With proven pathways and low product toxicity, the ecGEM solution space aligned well with observed phenotypes. Since this catabolic pathway provides only one-third of the ATP of alcoholic fermentation (2/3 versus 2 ATP per glucose), the ecGEM predicted a growth decrease from 0.36 h-1 in the reference to 0.175 h-1 in the engineered strain. However, this <3-fold decrease would require the specific glucose consumption rate to increase. Surprisingly, after the pathway swap the engineered strain immediately grew at 0.15 h-1 with a glucose consumption rate of 29 mmol (g CDW)-1 h-1, which was indeed higher than reference (23 mmol (g CDW)-1 h-1) and one of the highest reported for S. cerevisiae. The accompanying 2,3-butanediol- (15.8 mmol (g CDW)-1 h-1) and glycerol (19.6 mmol (g CDW)-1 h-1) production rates were close to predicted values. Proteomics confirmed that this increased consumption rate was facilitated by enzyme reallocation from especially ribosomes (from 25.5 to 18.5 %) towards glycolysis (from 28.7 to 43.5 %). Subsequently, 200 generations of sequential transfer did not improve growth of the engineered strain, showing the use of ecGEMs in predicting opportunity space for laboratory evolution. The observations in this study illustrate both the current potential, as well as future improvements, of ecGEMs as a tool for both metabolic engineering and laboratory evolution.

Effects of photoaging on structure and characteristics of biofilms on microplastic in soil: Biomass and microbial community.

Understanding of the environmental behaviors of microplastics is limited by a lack of knowledge about how photoaging influences biofilm formation on microplastics in soil. Here, original microplastics (OMPs) and photoaged-microplastics (AMPs) were incubated in soil to study the effect of photoaging on formation and characteristics of biofilm on the poly (butylene succinate) microplastics. Because photoaging decreased the hydrophobicity of the microplastic, the biomass of biofilm on the OMPs was nearly twice that on the AMPs in the early stage of incubation. However, the significance of the substrate on biomass in the biofilm declined as the plastisphere developed. The bacterial communities in the plastisphere were distinct from, and less diverse than, those in surrounding soil. The dominant genera in the OMPs and AMPs plastispheres were Achromobacter and Burkholderia, respectively, indicating that photoaging changed the composition of the bacterial community of biofilm at the genus level. Meantime, photoaging decreased the complexity and stability of the plastisphere bacterial community network. Results of Biolog ECO-microplate assays and functional prediction from amplicons showed that photoaging treatment enhanced the carbon metabolic capacity of the microplastic biofilm. This study provides new insights into the formation of plastispheres in soil.

Comparison of Yield Characteristics, Chemical Composition, Lignans Content and Antioxidant Potential of Experimentally Grown Six Linseed (Linum usitatissimum L.) Cultivars.

Linseed represents a rich source of nutritional, functional and health-beneficial compounds. Nevertheless, the chemical composition and content of bioactive compounds may be quite variable and potentially affected by various factors, including genotype and the environment. In this study, the proximate chemical composition, lignans content and antioxidant potential of six experimentally grown linseed cultivars were assessed and compared. A diagonal cultivation trial in the University of South Bohemia Experimental Station in Ceské Budejovice, Czech Republic, was established in three subsequent growing seasons (2018, 2019 and 2020). The results showed that the cultivar and growing conditions influenced most studied parameters. The lack of precipitation in May and June 2019 negatively affected the seed yield and the level of secoisolariciresinol diglucoside but did not decrease the crude protein content, which was negatively related to the oil content. The newly developed method for lignans analysis allowed the identification and quantification of secoisolariciresinol diglucoside and matairesinol. Their content correlated positively with the total polyphenol content and antioxidant assays (DPPH and ABTS radical scavenging activity), indicating the significant contribution to the biofunctional properties of linseed. On the other hand, we did not detect minor linseed lignans, pinoresinol and lariciresinol. The results of this study showed the importance of cultivar and growing conditions factors on the linseed chemical composition and the lignans content, determining its nutritional and medicinal properties.

Systemic metabolic engineering of Enterobacter aerogenes for efficient 2,3-butanediol production.

2,3-Butanediol (2,3-BDO) is an important gateway molecule for many chemical derivatives. Currently, microbial production is gradually being recognized as a green and sustainable alternative to petrochemical synthesis, but the titer, yield, and productivity of microbial 2,3-BDO remain suboptimal. Here, we used systemic metabolic engineering strategies to debottleneck the 2,3-BDO production in Enterobacter aerogenes. Firstly, the pyruvate metabolic network was reconstructed by deleting genes for by-product synthesis to improve the flux toward 2,3-BDO synthesis, which resulted in a 90% increase of the product titer. Secondly, the 2,3-BDO productivity of the IAM1183-LPCT/D was increased by 55% due to the heterologous expression of DR1558 which boosted cell resistance to abiotic stress. Thirdly, carbon sources were optimized to further improve the yield of target products. The IAM1183-LPCT/D showed the highest titer of 2,3-BDO from sucrose, 20% higher than that from glucose, and the yield of 2,3-BDO reached 0.49 g/g. Finally, the titer of 2,3-BDO of IAM1183-LPCT/D in a 5-L fermenter reached 22.93 g/L, 85% higher than the wild-type strain, and the titer of by-products except ethanol was very low. KEY POINTS: Deletion of five key genes in E. aerogenes improved 2,3-BDO production The titer of 2,3-BDO was increased by 90% by regulating metabolic flux Response regulator DR1558 was expressed to increase 2,3-BDO productivity.

Unexpectedly stable homopurine parallel triplex of SNA:RNA*SNA and L-aTNA:RNA*L-aTNA.

Homopurine strands are known to form antiparallel triplexes stabilized by G*G and A*A Hoogsteen pairs, which have two hydrogen bonds. But there has been no report on the parallel triplex formation of homopurine involving both adenosine and guanosine to the duplex. In this paper, we first report parallel triplex formation between a homopurine serinol nucleic acid (SNA) strand and an RNA/SNA duplex. Melting profiles revealed that the parallel SNA:RNA*SNA triplex was remarkably stable, even though the A*A pair has a single hydrogen bond. An L-acyclic threoninol nucleic acid (L-aTNA) homopurine strand also formed a stable parallel triplex with an L-aTNA/RNA duplex.

Efficient L-valine production using systematically metabolic engineered Klebsiella oxytoca.

L-Valine, a branched-chain amino acid with diversified applications, is biosynthesized with α-acetolactate as the key precursor. In this study, the metabolic flux in Klebsiella oxytoca PDL-K5, a Risk Group 1 organism producing 2,3-butanediol as the major fermentation product, was rearranged to L-valine production by introducing exogenous L-valine biosynthesis pathway and blocking endogenous 2,3-butanediol generation at the metabolic branch point α-acetolactate. After further enhancing L-valine efflux, strengthening pyruvate polymerization and selecting of key enzymes for L-valine synthesis, a plasmid-free K. oxytoca strain VKO-9 was obtained. Fed-batch fermentation with K. oxytoca VKO-9 in a 7.5 L fermenter generated 122 g/L L-valine with a yield of 0.587 g/g in 56 h. In addition, repeated fed-batch fermentation was conducted to prevent precipitation of L-valine due to oversaturation. The average concentration, yield, and productivity of produced L-valine in three cycles of repeated fed-batch fermentation were 81.3 g/L, 0.599 g/g, and 3.39 g/L/h, respectively.

Bio-based epoxidized soybean oil branched cardanol ethers as compatibilizers of polybutylene succinate (PBS)/polyglycolic acid (PGA) blends.

Blending poly(butylene succinate) (PBS) with another biodegradable polymer, polyglycolic acid (PGA), has been demonstrated to improve the barrier performance of PBS. However, blending these two polymers poses a challenge because of their incompatibility and large difference of their melting temperatures. In this study, we synthesized epoxidized soybean oil branched cardanol ether (ESOn-ECD), a bio-based and environmentally friendly compatibilizer, and used it to enhance the compatibility of PBS/PGA blends. It was demonstrated that the terminal carboxyl/hydroxyl groups of PBS and PGA can react with ESOn-ECD in situ, leading to branching and chain extension of PBS and PGA. The addition of ESO3-ECD to the blend considerably diminished the dispersed phase of PGA. Specifically, in comparison to the PBS/PGA blend without a compatibilizer, the diameter of the PGA phase decreased from 2.04 µm to 0.45 µm after the addition of 0.7 phr of ESO3-ECD, and the boundary between the two phases became difficult to distinguish. Additionally, the mechanical properties of the blends were improved after addition of ESO3-ECD. This research expands the potential applications of these materials and promotes the use of bio-based components in blend formulations.

Limiting acetoin generation during 2,3-butanediol fermentation with Paenibacillus polymyxa using lignocellulosic hydrolysates.

Recent decarbonization efforts have led to interests in producing more bio-based chemicals. One attractive compound produced biochemically is the platform chemical known as 2,3-butanediol (2,3-BDO). In this work a mild alkaline pretreatment using sodium carbonate was performed on corn stover (CS) and switchgrass (SG) to generate hydrolysates for fermentation with the 2,3-BDO producer bacteria strain Paenibacillius polymyxa. Enzymatic hydrolysis performed on the pretreated CS and SG produced theoretical sugar yields of 80 % and 95 % for glucose and xylose, respectively. Fermentations with P. polymxya conducted in anaerobic bottles produced 2,3-BDO reaching concentrations ranging from 14 to 18 g/L with negligible conversion into acetoin. Bioreactor fermentations using the hydrolysate media generated up to 43 g/L and 34 g/L of 2,3-BDO from pretreated CS and SG, respectively, within 24 h of fermentation. However, 2,3-BDO product output was reduced by 40-50 % over the remainder of the fermentation due to conversion into acetoin caused by glucose depletion.

Effects of 1,3-propanediol associated, or not, with butylene glycol and/or glycerol on skin hydration and skin barrier function.

OBJECTIVE: This study aimed to assess the effect of 1,3-propanediol at different concentrations (5%, 10%, or 15%), either applied alone or in combination with butylene glycol (BG) (5%) and/or glycerol (5%), on skin hydration and skin barrier function. The measurements were conducted using capacitance to determine skin hydration and trans epidermal water loss (TEWL) rates to evaluate skin barrier function. METHODS: A total of 30 healthy female subjects participated in the study. Capacitance and TEWL measurements were conducted at multiple time points, including before application and at 15 min, 2 and 8 h after the humectants were applied to the forearms of the subjects. All the subjects provided written informed consent. RESULTS: The 1,3-propanediol in all concentrations and in all combinations (with BG and/or glycerol) increased skin hydration and improved skin barrier function 15 min, 2 and 8 h after application. Glycerol increased the hydration performance of 1,3-propanediol. The application of 1,3-propanediol at a concentration of 15%, either alone or in combination with other humectants, reduced the TEWL to a greater extent than lower concentrations of 1,3-propanediol. Furthermore, the addition of glycerol to 1,3-propanediol 15% improved the skin barrier and reduced TEWL when compared with 1,3-propanediol alone and with the combination of 1,3-propanediol + BG. CONCLUSION: The humectants significantly improved skin hydration and reduced TEWL throughout the 8-h time course. The increase in 1,3-propanediol concentration, as well as its combination with glycerol, provided a greater benefit to the skin, improving both hydration and the skin barrier function.

OBJECTIF: Cette étude visait à évaluer l'effet sur l'hydratation de la peau et la fonction de barrière cutanée du 1,3-propanediol à différentes concentrations (5 %, 10 % ou 15 %), appliqué seul ou en association avec du butylène glycol (5 %) et/ou du glycérol (5 %). Les mesures ont été effectuées à l'aide de la capacitance pour déterminer l'hydratation de la peau et les taux de perte d'eau transépidermique (Trans Epidermal Water Loss, TEWL) pour évaluer la fonction de barrière cutanée. MÉTHODES: Au total, 30 sujets de sexe féminin en bonne santé ont participé à l'étude. Les mesures de la capacitance et de la TEWL ont été effectuées à plusieurs moments, y compris avant l'application, 15 minutes, 2 heures et 8 heures après l'application des produits humectant sur les avant-bras des sujets. Tous les sujets ont fourni un consentement éclairé écrit. RÉSULTATS: Le 1,3-propanediol, à toutes les concentrations et dans toutes les associations (avec le butylène glycol et/ou le glycérol), a augmenté l'hydratation de la peau et amélioré la fonction de barrière cutanée à 15 minutes, 2 heures et 8 heures après l'application. Le glycérol a augmenté les performances d'hydratation du 1,3-propanediol. L'application de 1,3-propanediol à une concentration de 15 %, seul ou en association avec d'autres produits humectant, a réduit la TEWL dans une plus grande mesure que des concentrations inférieures de 1,3-propanediol. En outre, l'ajout de glycérol au 1,3-propanediol 15 % a amélioré la barrière cutanée et réduit la TEWL par rapport au 1,3-propanediol seul et à l'association 1,3-propanediol + butylène glycol. CONCLUSION: Les produits humectant ont significativement amélioré l'hydratation de la peau et réduit la TEWL tout au long des 8 heures. L'augmentation de la concentration de 1,3-propanediol, ainsi que son association avec le glycérol, ont apporté un plus grand bénéfice à la peau, améliorant à la fois l'hydratation et la fonction de barrière cutanée.

Cross-Reactivity Between Propylene Glycol and Butylene Glycol.

Background: Propylene glycol (PG) and butylene glycol (BG) are not known to be cross-reactors. However, no large-scale studies have assessed the cross-reactivity rate (CRR) between these 2 structurally and functionally similar compounds. Objectives: The aim of this study was to determine whether PG and BG demonstrate cross-reactivity. Methods: This is a retrospective chart review of 893 patients who underwent patch testing for both PG and BG from 2020 to 2022. The frequencies of positive reactions and concomitant reaction rates were calculated. Results: In our cohort, 53 (5.94%) patients reacted to PG and 13 patients (1.46%) reacted to BG. Of the patients who reacted to PG, 6 reacted to BG representing a CRR of 11.3%, whereas the CRR to PG in BG-allergic patients was 46.2%. Conclusions: For those allergic to BG, PG should be considered a cross-reactor. This relationship is somewhat unidirectional, as patients allergic to PG demonstrated a CRR to BG of only 11.3%, significantly lower than the 46.2% CRR to PG among BG-allergic patients.

Metabolic engineering of Caldicellulosiruptor bescii for 2,3-butanediol production from unpretreated lignocellulosic biomass and metabolic strategies for improving yields and titers.

The platform chemical 2,3-butanediol (2,3-BDO) is used to derive products, such as 1,3-butadiene and methyl ethyl ketone, for the chemical and fuel production industries. Efficient microbial 2,3-BDO production at industrial scales has not been achieved yet for various reasons, including product inhibition to host organisms, mixed stereospecificity in product formation, and dependence on expensive substrates (i.e., glucose). In this study, we explore engineering of a 2,3-BDO pathway in Caldicellulosiruptor bescii, an extremely thermophilic (optimal growth temperature = 78°C) and anaerobic bacterium that can break down crystalline cellulose and hemicellulose into fermentable C5 and C6 sugars. In addition, C. bescii grows on unpretreated plant biomass, such as switchgrass. Biosynthesis of 2,3-BDO involves three steps: two molecules of pyruvate are condensed into acetolactate; acetolactate is decarboxylated to acetoin, and finally, acetoin is reduced to 2,3-BDO. C. bescii natively produces acetoin; therefore, in order to complete the 2,3-BDO biosynthetic pathway, C. bescii was engineered to produce a secondary alcohol dehydrogenase (sADH) to catalyze the final step. Two previously characterized, thermostable sADH enzymes with high affinity for acetoin, one from a bacterium and one from an archaeon, were tested independently. When either sADH was present in C. bescii, the recombinant strains were able to produce up to 2.5-mM 2,3-BDO from crystalline cellulose and xylan and 0.2-mM 2,3-BDO directly from unpretreated switchgrass. This serves as the basis for higher yields and productivities, and to this end, limiting factors and potential genetic targets for further optimization were assessed using the genome-scale metabolic model of C. bescii.IMPORTANCELignocellulosic plant biomass as the substrate for microbial synthesis of 2,3-butanediol is one of the major keys toward cost-effective bio-based production of this chemical at an industrial scale. However, deconstruction of biomass to release the sugars for microbial growth currently requires expensive thermochemical and enzymatic pretreatments. In this study, the thermo-cellulolytic bacterium Caldicellulosiruptor bescii was successfully engineered to produce 2,3-butanediol from cellulose, xylan, and directly from unpretreated switchgrass. Genome-scale metabolic modeling of C. bescii was applied to adjust carbon and redox fluxes to maximize productivity of 2,3-butanediol, thereby revealing bottlenecks that require genetic modifications.

Metabolic Engineering of Escherichia coli for De Novo Production of 1,2-Butanediol.

1,2-Butanediol (1,2-BDO) is an important platform chemical widely utilized in the synthesis of polyester polyols, plasticizers, cosmetics, and pharmaceuticals. However, no natural metabolic pathway for its biosynthesis has been identified, and biological production of 1,2-BDO from renewable bioresources has not been reported so far. In this study, we designed and experimentally verified a feasible non-natural synthesis pathway for the de novo production of 1,2-BDO from renewable carbohydrates for the first time. This pathway extends the l-threonine synthesis pathway by introducing two artificial metabolic modules to sequentially convert l-threonine into 2-hydroxybutyric acid and 1,2-BDO. Following key enzyme screening and enhancement of l-threonine synthesis module in the chassis microorganism, the best engineered Escherichia coli strain was able to produce 0.15 g/L 1,2-BDO using glucose as the sole carbon source. This work lays the foundation for the bioproduction of 1,2-BDO from renewable resources.