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The utilization of biomass resources in the production of bio‐based or bio‐recycled polyurethanes (PUs) enhances the sustainable development and eco‐friendliness of PU. Herein, a series of new bio‐based aliphatic poly(propylene dicarboxylate) diols were synthesized using bio‐based 1,3‐propanediol (bio‐PDO) and aliphatic dicarboxylic acids with different chain lengths. These bio‐based polyester diols and 1,4‐butanediol (BDO) reacted with 4,4′‐dicyclohexylmethane diisocyanate to produce aliphatic PU elastomers (PUEs). The study aimed to evaluate the impact of the structure of poly(propylene dicarboxylate) diols on the architecture, morphology, mechanical properties, and degradation of PUEs, thereby expanding the application of bio‐PDO. The results indicate a strong correlation between the degree of microphase separation, tensile properties, and degradation behavior of the synthesized PUEs and the number of methylene groups in the repeating unit of the poly(propylene dicarboxylate) diols. Notably, the PUE derived from poly(propylene pimelate) diol demonstrates the highest level of microphase separation and superior elasticity properties because of the high flexibility of the polyester. On the other hand, PUE prepared from poly(propylene succinate) diol exhibits the fastest degradation performance due to its high density of ester groups. Bio‐PDO based polyester diols show significant potential as raw materials for PUEs with biodegradable and adjustable mechanical properties. Highlights: Poly(propylene dicarboxylate) diols were prepared from bio‐based 1,3‐propanediol.The poly(propylene dicarboxylate) diols based polyurethane elastomers (PUEs) have high tensile strength (>22 MPa) and elongation at break (>920%).The morphology, mechanical properties and degradation of PUEs are highly related to the structure of the poly(propylene dicarboxylate) diols.The increasing repeating unit length of the poly(propylene dicarboxylate) diols increases elastic recovery of PUEs. [ABSTRACT FROM AUTHOR]

1,3‐Propanediol (1,3‐PDO) has multiple practical applications, for example as an antifreeze and protective agent and as a monomer of partially renewable polyester and polyurethane. The main method for 1,3‐PDO production is currently microbial fermentation. Bio‐based 1,3‐PDO can use renewable materials as substrates, and the process is mild and environmentally friendly.Genetic engineering of microorganisms is crucial to achieve substrate diversity, reduce byproducts to decrease production costs, and facilitate the downstream processing of 1,3‐PDO. This paper reviews the metabolic engineering of 1,3‐PDO in natural and non‐natural producers. In particular, it discusses current progress using non‐natural synthetic pathways to obtain 1,3‐propanediol.Finally, strategies such as integrated production with other high‐value‐added products are proposed for successful commercialization. [ABSTRACT FROM AUTHOR]

A one-pot, one-step protocol combining hydrogen transfer initiated dehydration (HTID) of 1,3-propanediol (1,3-PDO), catalysed by [Cp*IrCl2(NHC)] (Cp* = pentamethylcyclopentadienyl; NHC = carbene ligand) complexes (1-5H and 1-3F), and self-aldol condensation (SAC) of propanal (2), allowed selective production of C6 aldehyde 2-methyl-pent-2-enal (3), in ionic liquids with high substrate conversion. This shows, for the first time, the conversion of 1,3-propanediol to C6 aldehydes in one pot via a catalytic hydrogen borrowing methodology. The Ir(III) pre-catalysts and the ionic liquids were recyclable. C6 aldehyde 2-methyl-pent-2-enal could also be selectively produced in the presence of water and in neat 1,3-PDO. The efficient, selective delivery of a value-added chemical from 1,3-PDO, a major product of many whole-cell bacterial fermentation processes, shows that the combination of chemo-catalytic processing of the chemical platform via Cp*IrCl2(NHC)-catalysed HTID/SAC with bio-catalysis has the potential to allow direct valorisation of the bio-renewable feedstocks, such as waste glycerol and sugars, into valuable chemicals. [ABSTRACT FROM AUTHOR]

PDO (1,3-propanediol) is a platform chemical that is obtained by petrochemical routes and by fermentation. The latter needs relatively complex downstream processing after fermentation, due to the modest concentration of the high-boiling product, and the presence of microorganisms and many impurities in the fermentation medium. This novel research proposes an original large-scale (production capacity of 23 – 32 ktonne/y) process for the final purification of PDO and dominant by-products, from the fermentation of glucose or glycerol. Following the initial microfiltration, diafiltration, ultrafiltration and ion exchange steps, heat pump-assisted vacuum distillation was implemented to remove most of the water from the broth. Afterwards, an advanced highly-integrated dividing-wall column was designed to allow the final purification of PDO (product purity > 99.9 wt%) from light and heavy by-products. Fermentation by-products that are present in significant amounts can also be recovered and valorized. Overall, the developed final purification processes demonstrate cost-effectiveness (0.150 – 0.274 $/kg) and energy-efficiency (1.258 – 3.175 kW th h/kg) which contributes to the competitiveness of the overall downstream processing (0.256 – 0.384 $/kg and 1.487 – 3.496 kW th h/kg). [Display omitted] • Eco-efficient and fermentation-adjustable downstream processing of 1,3-propanediol • PDO and by-products can all be recovered at high purity and valorized accordingly • Low energy intensity (1.25–3.17 kW th h/kg) and cost-effective process (0.15–0.27 $/kg) • Competitive overall downstream processing (0.25–0.38 $/kg; 1.48–3.49 kW th h/kg) [ABSTRACT FROM AUTHOR]

In this work, the absorption of sulfur dioxide (SO2) was investigated using the 1,3-propanediol (PDO) + dimethyl sulfoxide (DMSO) system, and the gas−liquid equilibrium (GLE) data were analyzed over a temperature range of 298.15–318.15 K (with a temperature gradient of 5 K) at a pressure of 123.15 kPa. By fitting the gas–liquid equilibrium data, it is observed that the process of absorption SO2 conforms to Henry's Law. The change in specific entropy, enthalpy, and Gibbs free energies of the SO2 absorption process was as well calculated. In addition, the capture and regeneration properties of the PDO + DMSO system were investigated under atmospheric pressure, and the results of regeneration experiments demonstrated that 97.3% of SO2 could be desorbed by heating and bubbling with N2. Furthermore, there was no notable reduction in absorption capacity of the absorbent solvents after multiple cycles. Finally, the FTIR spectra and computational information were noted to analyze the interaction between SO2 and the system. As a result, an intermolecular hydrogen bonding association between PDO, DMSO, and SO2 can be inferred. [ABSTRACT FROM AUTHOR]

Abstract As an alternative to antibiotics in response to antimicrobial-resistant infections, bacteriophages (phages) are garnering renewed interest in recent years. However, the massive preparation of phage is restricted using traditional pathogens as host cells, which incurs additional costs and contamination. In this study, an opportunistic pathogen, Klebsiella pneumoniae used to convert glycerol to 1,3-propanediol (1,3-PDO), was reused to prepare phage after fermentation. The phage infection showed that the fed-batch fermentation broth containing 71.6 g/L 1,3-PDO can be directly used for preparation of phage with a titer of 1 × 108 pfu/mL. Then, the two-step salting-out extraction was adopted to remove most impurities, e.g. acetic acid (93.5%), ethanol (91.5%) and cells (99.4%) at the first step, and obtain 1,3-PDO (56.6%) in the top phase as well as phage (97.4%) in the middle phase at the second step. This integrated process provides a cheap and environment-friendly manner for coproduction of 1,3-PDO and phage. Graphical abstract

The individual ingredients of 1,3-Propanediol, Soline, and Fucocert® (PSF) are often used as cosmetic formulations in skin care. In addition, the mixture of Lecigel, Cetiol®CC, Activonol-6, and Activonol-M (LCAA) is often used as a cosmetic base. However, whether the combination of LCAA with PSF (LCAA-PSF) exerts a therapeutic effect on psoriasis remains unclear. In this study, mice induced with imiquimod (IMQ) were divided into three groups and administered 100 mg/day of LCAA, 100 mg/day of LCAA-PSF, or Vaseline on the dorsal skin of each mouse. Weight-matched mice treated with Vaseline alone were used as controls. Hematoxylin and eosin (H&E) staining and enzyme-linked immunosorbent assay(ELISA) were used to assess tissue morphology and inflammatory cytokines. RNA sequencing analysis was used to predict the mechanism underlying the action of LCAA-PSF against psoriasis, while immunohistochemical analysis validation was used to identify pertinent molecular pathways. The results demonstrated that LCAA-PSF alleviated IMQ-induced keratinocyte differentiation/ proliferation bydecreasingthe serum levels of inflammatory cytokines such as IL-6, TNF-α, IL-23, and IL-17A and the epidermisof TGFβ, Ki67, CK5/6, and VEGF expression, which is associated with angiogenesis and keratinocyte differentiation/ proliferation. These findings highlight the antipsoriatic activity of LCAA-PSF in a psoriasis-like mouse model and suggest this may occurvia the inhibition of inflammatory factor secretionand the TGFβ-related signal pathway. [ABSTRACT FROM AUTHOR]

The conversion of Methyl 3‐hydroxypropionate (3‐HPM) to 1,3‐propanediol (1, 3‐PDO) is an important step in the pathway towards the longterm sustainable production of the ethylene oxide hydroesterification. However, 3‐HPM is prone to side reactions like hydroxyl β‐dehydration and low reaction efficiency, which hinders its development. This study presents the first‐ever report on highly efficient gallium‐promoted Cu/SiO2 catalysts prepared using ethanol‐assisted ammonia‐evaporation (Et‐AE) for converting 3‐HPM to 1,3‐PDO. The prepared Cu‐1Ga/SiO2 catalyst exhibited satisfactory catalytic activity and 1,3‐PDO selectivity in the hydrogenation reaction, with a conversion of 3‐HPM of 94 % and a selectivity to 1,3‐PDO of 91 %. The characterisation results show that the addition of Ga increases the specific surface area and the pore volume of the catalyst, and also increases the dispersion of the Cu species. And the promotional effect likely originates from interactions between Ga3+ and Cu0 species though enhanced ability of the latter to activate H2. In addition, the introduction of Ga into the catalyst increases the interaction between Cu and the support, making it more difficult for Cu+ to be completely reduced to Cu0. This increases the content of Cu+ in the catalyst, which is beneficial for improving the activity and stability of the catalyst. This study investigates modifying Cu catalysts to provide guidelines for obtaining high performing hydrogenation catalysts. [ABSTRACT FROM AUTHOR]

A reactor with silicone tubes as support medium was used for glycerol fermentation. The experimental set-up consisted of three phases. In P1, the applied glycerol loading rate (gly-LR) was in the range of 6–10 g.L−1.d−1 at an influent pH of 7.9 ± 0.4. In P2, gly-LR was kept constant (18.0 ± 1.8 g.L−1.d−1) with different doses of NaHCO3. Finally in P3, two different gly-LR (9 and 18 g.L−1.d−1) were evaluated, dosing 1 g-NaHCO3 per g-COD of glycerol. Glycerol consumption was close 90%. The main end-product was 1,3-propanediol (1,3-PDO) (0.40 mol.mol-gly−1), but ethanol was also generated, particularly at pH above 8 and low gly-LR (0.20 mol.mol-gly−1). After 1-year operation with glycerol as the only carbon source, a drastic shift in the bacterial community was observed. The 1,3-PDO producers Lacrimispora and Clostridium became dominant, although non-glycerol-degrading fermentative genera, e.g., Actinomyces and Eubacterium, thrived at the expense of cellular breakdown products. [ABSTRACT FROM AUTHOR]

BACKGROUND: Conventional methods for the separation of 1,3‐propanediol (1,3‐PDO) are problematic in many ways. The study of a simple and efficient separation process was the key to solving the bottlenecks that have restricted the large‐scale development of 1,3‐PDO. In order to solve the difficulty of separating 1,3‐PDO from fermentation broths, a ternary selective extraction system was constructed to separate 1,3‐PDO from a simulated solution and fermentation broth. RESULTS: In this study, quantum chemistry calculation and wave function analysis showed that the reaction between phenylboronic acid and 1,3‐PDO is thermodynamically feasible, stable and covalently reversible. The ternary extraction system was composed of 1‐naphthylboric acid, dichloromethane and Aliquat 336. After optimization of the extraction conditions, a high extraction efficiency of 82.6% could be achieved for 1,3‐PDO. Meanwhile, the stripping recovery of 1,3‐PDO was over 90%, with a high purity (98.6%), from a simulated solution using 0.4 mol L−1 hydrochloric acid as stripping solution. The extraction selectivity of 1,3‐PDO to glycerol, acetic acid and butyric acid in the fermentation broth reached 12.9, 230.6 and 233.7, respectively, implying a high selective performance compared with the aldehyde‐based traditional reactive extraction. CONCLUSION: The ternary extraction system exhibited good extraction performance, highlighting the potential for selective extraction of diol biochemicals from fermentation broths. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Cu catalysts with different compositions and different Cu and promoter contents were prepared by precipitation‐gel method and studied for the selective hydrogenation of syngas or biomass‐based diethyl malonate (DEM) to valuable 1,3‐propanediol (1,3‐PDO). The Ga‐promoted 70Cu6Ga/SiO2 catalyst was found to exhibit the highest catalytic performance, achieving 100 % DEM conversion and 76.6 % 1,3‐PDO selectivity under reaction conditions of 160 °C and 8 MPa H2. The 70Cu6Ga/SiO2 bimetallic catalyst also presented obviously better stability than that of the monometallic 70Cu/SiO2 catalyst in a continuous flow reactor over 180 h time‐on stream. Characterization results showed that the incorporation of Ga increased the interaction between Cu and Ga species, hindered the full reduction of Cu2+ species, and thus increased the proportion of Cu+ and the number of Lewis acidic sites on the catalyst surface. The synergistic effect between Cu0 and Cu+ enhanced the adsorption and activation of ester carbonyl groups and their subsequent hydrogenation, eventually contributed to the outstanding performances of the CuGa/SiO2 bimetallic catalysts. [ABSTRACT FROM AUTHOR]

Context: 1,3-Propanediol (1,3-PDO) is a key chemical in various industries, including pharmaceuticals and material sciences, and is projected to see significant market growth. However, the current challenges in its downstream processing, particularly in terms of cost and efficiency, highlight the need for innovative solutions. Our study delves into using ionic liquids (ILs) as a potential alternative, aiming to address these critical separation challenges more sustainably and efficiently. In this study, we utilized molecular dynamics (MD) simulations and the COSMO-SAC to examine 1,3-propanediol (1,3-PDO) extraction using four imidazolium-based ionic liquids with 1-butyl-3-methylimidazolium [Bmim] cation and with different anions bis(pentafluoroethanesulfonyl)imide [NPF2]−, bis(trifluoromethylsulfonyl)imide [NTF2]−, thiocyanate [SCN]−, and trifluoromethanesulfonate [TFO]−. Molecular dynamics simulations, incorporating analysis of radial distribution functions (RDF) and spatial distribution functions (SDF), revealed that [Bmim][SCN] and [Bmim][TFO] exhibit enhanced interactions with 1,3-PDO. Notably, [Bmim][SCN] formed the most hydrogen bonds, averaging 1.639 per molecule, due to its coordinating [SCN]− anion. This was in contrast to the fewer hydrogen bonds formed by non-coordinating anions in [Bmim][NPF2] and [Bmim][NTF2]. In ternary systems, [Bmim][SCN] and [Bmim][TFO] demonstrated superior selectivity for 1,3-PDO extraction compared to the other ionic liquids, with selectivity values around 29. These findings, supported by COSMO-SAC predictive modeling, highlight the potential of [Bmim][SCN] as a promising candidate for 1,3-PDO extraction, emphasizing the importance of anion selection in optimizing ionic liquid properties for this application. Methods: In our study, we employed MD simulations, incorporating the OPLS-AA force field, and COSMO-SAC to investigate the extraction of 1,3-PDO using imidazolium-based ionic liquids: [Bmim][NTF2], [Bmim][NPF2], [Bmim][SCN], and [Bmim][TFO]. The MD simulations were conducted using LAMMPS software, focusing on elucidating the RDF, SDF, and hydrogen bonding. Analysis of the distribution coefficient (β) and selectivity (S) for the ternary mixture was also conducted. These aspects of the simulation were analyzed using TRAVIS and VMD software. Additionally, the COSMO-SAC model was employed to determine the activity coefficients of 1,3-PDO in the ionic liquids, with molecular optimization conducted using Gaussian16 and sigma profile calculations performed using COSMO-SAC. [ABSTRACT FROM AUTHOR]

BACKGROUND: 1,3‐Propanediol (PDO) is a raw material/specialty chemical/additive in several industrial applications. A new wild‐type Clostridium strain BOH3 can utilize crude glycerol (CG) and produce PDO. This investigation reveals its potential for PDO production from CG. RESULTS: Initially, inoculum of strain BOH3 was cultured from reinforced clostridial medium (RCM) with glucose (medium‐A), and modified‐RCM with glycerol (medium‐B). While fermenting 20 g L−1 glycerol, the cells cultivated from medium‐A produced 5.75 g L−1 PDO (as major product) with 3.10 g L−1 butanol (byproduct), whereas the cells cultivated from medium‐B produced 11.01 g L−1 PDO with 2.50 g L−1 butyric acid and 1.01 g L−1 acetic acid, with no butanol produced. To enhance PDO production from the batch‐process, various parameters including pure glycerol/CG concentration (80 g L−1), inoculum age (15 h) and size (12.50%v/v) of cells from medium‐B, initial medium‐pH (pH 6.4) and incubation temperature (39 °C) were studied; the optimal values obtained are given in their respective parenthesis. Under optimal conditions, PDO production was 42.58–47.15 g L−1 (0.65–0.79 mol‐PDO/mol‐glycerol) from CG‐based rich/mineral media. Furthermore, fed‐batch fermentation with 50–80 g L−1 initial CG‐concentration was tested to enhance the PDO production. Among these, 60 g L−1 initial CG‐concentration assisted strain BOH3 in utilizing a high level of CG (~174 g L−1); it supported a higher‐titer of PDO production (103.55–116.45 g L−1), with the highest yield (0.72–0.81 mol−PDO/mol−glycerol) ever reported. CONCLUSION: Clostridium strain BOH3 shows the potential to support a high titer (>116 g L−1) with the highest yield (>0.80 mol mol−1) of PDO production from CG (a waste). It can be considered for industrial‐scale PDO production. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

As an alternative to antibiotics in response to antimicrobial-resistant infections, bacteriophages (phages) are garnering renewed interest in recent years. However, the massive preparation of phage is restricted using traditional pathogens as host cells, which incurs additional costs and contamination. In this study, an opportunistic pathogen, Klebsiella pneumoniae used to convert glycerol to 1,3-propanediol (1,3-PDO), was reused to prepare phage after fermentation. The phage infection showed that the fed-batch fermentation broth containing 71.6 g/L 1,3-PDO can be directly used for preparation of phage with a titer of 1 × 108 pfu/mL. Then, the two-step salting-out extraction was adopted to remove most impurities, e.g. acetic acid (93.5%), ethanol (91.5%) and cells (99.4%) at the first step, and obtain 1,3-PDO (56.6%) in the top phase as well as phage (97.4%) in the middle phase at the second step. This integrated process provides a cheap and environment-friendly manner for coproduction of 1,3-PDO and phage. [ABSTRACT FROM AUTHOR]

This study investigates the application of crude glycerol to the production of 1,3-propanediol by immobilized cells of Bacillus pumilus. This is a novel application of a naturally occurring producer obtained from a wastewater storage pond in Thailand. Crude glycerol was obtained through the methanolysis of palm oil, which was catalyzed using rice bran lipase. Ten components of the fermentation medium were screened using a Plackett-Burman design. The statistical significance of the results was determined using multiple linear regression with a backward elimination approach. The significance level was set to 5 % (p

Abstract Background Glycerol, as a by-product, mainly derives from the conversion of many crops to biodiesel, ethanol, and fatty ester. Its bioconversion to 1,3-propanediol (1,3-PDO) is an environmentally friendly method. Continuous fermentation has many striking merits over fed-batch and batch fermentation, such as high product concentration with easy feeding operation, long-term high productivity without frequent seed culture, and energy-intensive sterilization. However, it is usually difficult to harvest high product concentrations. Results In this study, a three-stage continuous fermentation was firstly designed to produce 1,3-PDO from crude glycerol by Clostridium butyricum, in which the first stage fermentation was responsible for providing the excellent cells in a robust growth state, the second stage focused on promoting 1,3-PDO production, and the third stage aimed to further boost the 1,3-PDO concentration and reduce the residual glycerol concentration as much as possible. Through the three-stage continuous fermentation, 80.05 g/L 1,3-PDO as the maximum concentration was produced while maintaining residual glycerol of 5.87 g/L, achieving a yield of 0.48 g/g and a productivity of 3.67 g/(L·h). Based on the 14 sets of experimental data from the first stage, a kinetic model was developed to describe the intricate relationships among the concentrations of 1,3-PDO, substrate, biomass, and butyrate. Subsequently, this kinetic model was used to optimize and predict the highest 1,3-PDO productivity of 11.26 g/(L·h) in the first stage fermentation, while the glycerol feeding concentration and dilution rate were determined to be 92 g/L and 0.341 h−1, separately. Additionally, to achieve a target 1,3-PDO production of 80 g/L without the third stage fermentation, the predicted minimum volume ratio of the second fermenter to the first one was 11.9. The kinetics-based two-stage continuous fermentation was experimentally verified well with the predicted results. Conclusion A novel three-stage continuous fermentation and a kinetic model were reported. Then a simpler two-stage continuous fermentation was developed based on the optimization of the kinetic model. This kinetics-based development of two-stage continuous fermentation could achieve high-level production of 1,3-PDO. Meanwhile, it provides a reference for other bio-chemicals production by applying kinetics to optimize multi-stage continuous fermentation. Graphical Abstract

A total of 817 Lactobacillus-like isolates were obtained from different sources, including soil, ruminant gastric juice, and fermented foods. They were screened to select the best isolate for the production of 1,3-propanediol (1,3-PDO). The isolate SY235 was selected and designated as Lactobacillus reuteri based on the 16S rRNA gene sequence. It was then employed in fed-batch fermentation for producing 1,3-PDO. The highest titer of 1,3-PDO (52.6 ± 2.4 g/L) was attained at 60 h, corresponding to a yield of 0.55 ± 0.01 g/g glycerol and a productivity of 0.88 ± 0.04 g/L/h. No further production was observed after 60 h of incubation. These results demonstrate that the newly isolated strain L. reuteri SY235 can efficiently transform glycerol into 1,3-PDO. [ABSTRACT FROM AUTHOR]

Organometallic catalysts such as titanium‐based ones are often used for the melt polycondensation to obtain polyesters. However, they are prone to hydrolysis and may discolor, which may have adverse effects on the molecular weight of the resulting polyesters and their applications. This work aims to use functionalized UiO‐66 catalysts for the melt polycondensation of polyesters composed of 1,3‐propanediol and 1,10‐decanedioic acid ether. The melt polycondensation proceeds in two steps: esterification and polycondensation. A catalytic mechanism is proposed. Compared with tetrabutyl titanate, a classical catalyst, the functionalized UiO‐66 ones are more water resistant, less toxic to, and do not discolor. It yields poly(1,3‐propylene sebacate) with higher molecular weights. Thus, they are efficient and greener catalysts. [ABSTRACT FROM AUTHOR]

Background: Glycerol, as a by-product, mainly derives from the conversion of many crops to biodiesel, ethanol, and fatty ester. Its bioconversion to 1,3-propanediol (1,3-PDO) is an environmentally friendly method. Continuous fermentation has many striking merits over fed-batch and batch fermentation, such as high product concentration with easy feeding operation, long-term high productivity without frequent seed culture, and energy-intensive sterilization. However, it is usually difficult to harvest high product concentrations. Results: In this study, a three-stage continuous fermentation was firstly designed to produce 1,3-PDO from crude glycerol by Clostridium butyricum, in which the first stage fermentation was responsible for providing the excellent cells in a robust growth state, the second stage focused on promoting 1,3-PDO production, and the third stage aimed to further boost the 1,3-PDO concentration and reduce the residual glycerol concentration as much as possible. Through the three-stage continuous fermentation, 80.05 g/L 1,3-PDO as the maximum concentration was produced while maintaining residual glycerol of 5.87 g/L, achieving a yield of 0.48 g/g and a productivity of 3.67 g/(L·h). Based on the 14 sets of experimental data from the first stage, a kinetic model was developed to describe the intricate relationships among the concentrations of 1,3-PDO, substrate, biomass, and butyrate. Subsequently, this kinetic model was used to optimize and predict the highest 1,3-PDO productivity of 11.26 g/(L·h) in the first stage fermentation, while the glycerol feeding concentration and dilution rate were determined to be 92 g/L and 0.341 h−1, separately. Additionally, to achieve a target 1,3-PDO production of 80 g/L without the third stage fermentation, the predicted minimum volume ratio of the second fermenter to the first one was 11.9. The kinetics-based two-stage continuous fermentation was experimentally verified well with the predicted results. Conclusion: A novel three-stage continuous fermentation and a kinetic model were reported. Then a simpler two-stage continuous fermentation was developed based on the optimization of the kinetic model. This kinetics-based development of two-stage continuous fermentation could achieve high-level production of 1,3-PDO. Meanwhile, it provides a reference for other bio-chemicals production by applying kinetics to optimize multi-stage continuous fermentation. [ABSTRACT FROM AUTHOR]

Glycerol fermentation for 1,3-propanediol (1,3-PDO) production was studied in an anaerobic up-flow reactor with biomass attached to silicone support. A mixed microbial culture was activated to perform the biofilm formation and attachment to a silicone hose prior the reactor operation. The reactor was operated over 362 days divided into two phases (P). In P1 and P2, the reactor was continuously fed with pure and crude glycerol, respectively. The operation consisted of increasing the glycerol loading rates (gly-LR). The achieved highest 1,3-PDO average yields were 0.43 mol mol-gly−1 and 0.62 mol mol-gly−1 when applied gly-LR was 18 and 46 g L−1 d−1 in P1 and P2, respectively. A maximum 1,3-PDO productivity of 14.7 g L−1 d−1 was obtained in P2. The higher yields of 1,3-PDO when the feed changed from pure to crude glycerol indicated a change in the microbial community. These results show that the studied system can be very promising and cost-effective for converting crude glycerol into value-added products on large scale even at high loads. [ABSTRACT FROM AUTHOR]

The conversion of glycerol into 1,3‐propanediol (1,3‐PDO) has gained significant attention as a sustainable pathway within the biodiesel production chain. Limosilactobacillus reuteri, a bacterium capable of efficiently converting glycerol to 1,3‐PDO, holds promise for this application. In industrial biotechnology, the development of kinetic models is important for bioreactor design, process analysis and scalability, supporting the advancement of biorefineries and the bioeconomy. This study focuses on investigating the kinetics of co‐fermentation of glucose and glycerol by L. reuteri, utilizing data from previous batch culture experiments. Three different models were evaluated for these batch runs, and the parameters were adjusted using the Levenberg–Marquardt algorithm in conjunction with an integration method. The results from these previous batch experiments indicate that pH did not significantly influence the specific growth rate of the bacterium. However, as expected, reducing the temperature from 37 to 30°C resulted in a 60% reduction in the growth rate. Moreover, continuous co‐fermentation experiments were conducted, and a simple kinetic model was proposed. The advantage of the continuous process is that the productivity of 1,3‐PDO is 3.5 times higher compared with co‐fermentation in batch mode. Notably, this study represents the first attempt to model continuous co‐fermentation under a range of dilution rates (0.25–0.9 h−1), identifying a dilution rate of 0.5 h−1 as the optimal condition to produce 1,3‐PDO, considering productivity and substrate conversion. The findings of this research contribute valuable insights for future investigations on the viability of 1,3‐PDO production from glycerol, particularly within the context of waste valorization. [ABSTRACT FROM AUTHOR]

The bio‐based diols 1,3‐propanediol (1,3‐PDO) and 2,3‐butanediol (2,3‐BDO) can form strong hydrogen bonds with water, which increases the separation difficulty of diols in aqueous solutions. Herein, a series of mixed‐linker ZIF‐71‐clnImx samples with hydrogen bond–van der Waals (vdW) dual recognition sites have been constructed using 4‐chloro‐5‐nitroimidazole (clnIm) linkers to substitute partially for the original 4,5‐dichloroimidazole (dclIm) linkers of the ZIF‐71 framework. The experimental and calculated results show that ZIF‐71‐clnImx with appropriate clnIm substitution proportion (x = 7.6 and 12.8 mol%) can strengthen the interaction between ZIF‐71‐clnImx and 2,3‐BDO and enhance the adsorption and mass transfer of 2,3‐BDO, thus achieving the efficient separation of 2,3‐BDO/1,3‐PDO. Molecular simulation results further verify that 2,3‐BDO can simultaneously form strong H bonds with the –NO2 of the clnIm linker and weak vdW interactions with the –Cl of the dclIm linker, which are the mixed recognition sites for 2,3‐BDO adsorption intensification in aqueous solution for ZIF‐71‐clnImx. [ABSTRACT FROM AUTHOR]

To study the relationship between the yield of 1,3‐propanediol (1,3‐PDO) and the flux change of the Clostridium butyricum metabolic pathway, an optimized calculation method based on dynamic flux balance analysis was used by combining genome‐scale flux balance analysis with a kinetic model. A more comprehensive and extensive metabolic pathway was obtained by optimization calculations. The primary extended branches include: the dihydroxyacetone node, which enters the pentose phosphate pathway; the α‐oxoglutarate node, which has synthetic metabolic pathways for glutamic acid and amino acids; and the serine and homocysteine nodes, which produce cystathionine before homocysteine enters the methionine cycle pathway. According to the expanded metabolic network, the flux distribution of key nodes in the metabolic pathway and the relationship between the flux distribution ratio of nodes and the yield of 1,3‐PDO were analyzed. At the dihydroxyacetone node, the flux of dihydroxyacetone converted to dihydroxyacetone phosphate was positively correlated with the yield of 1,3‐PDO. As an important intermediate product, the flux change in the metabolic pathway of α‐oxoglutarate reacting with amino acids to produce glutamic acid is positively correlated with the yield. When pyruvate was used as the central node to convert into lactic acid and α‐oxoglutarate, the proportion of branch flux was negatively correlated with the yield of 1,3‐PDO. These studies provide a theoretical basis for the optimization and further study of the metabolic pathway of C. butyricum. [ABSTRACT FROM AUTHOR]

The redox imbalance is the major obstacle in the microbial production of 3-hydroxypropionic acid (3-HP). Co-production of propanediol (PDO) and 3-HP is an effective strategy to overcome the redox imbalance issue. The biocatalyst Klebsiellapneumoniae naturally co-produces PDO and 3-HP. Its poor growth characteristics and excessive production of lipopolysaccharide hurdle its usage in industries. The objective of this study is to circumvent these constraints by isolating a novel strain of K.quasipneumoniae MSN12 (KpMSN12) from soil samples. From a numerous isolate, the new isolate KpMSN12 has produced 58 mM PDO and 4 mM 3-HP, when it was grown in shake flask under microaerobic conditions, which is higher than the control Kp109. The effect of overexpression of an aldH (KGSADH) on co-production of 3-HP and PDO from glycerol was investigated in recombinant KpMSN12 (KpMSN12K). KpMSN12K produced 45 mM of 3-HP and 30 mM PDO which was observed higher (3-HP 25 mM, PDO 28 mM) than the control strain. While over expressing dhaB in another recombinant (KpMSN12D), 3-HP was reduced to 9 mM and 11 mM PDO due to the accumulation of 3-HPA and the growth was severely hampered. In addition, combined overexpression of dhaB and aldH (KpMSN12DK) produced 33 mM 3-HP and 25 mM PDO. The lower lipopolysaccharide content in the KpMSN12 strain was confirmed by comparing 2-keto3-deoxyoctonate content (KpMSN12—3.8 µg/mL; Kp109—5.14 µg/mL). In addition, this new strain exhibited enhanced sedimentation characteristics and higher susceptibility to a variety of antibiotics when compared to Kp109 strain. These potential characteristics of KpMSN12 would shape it as a desirable host for the production of industrial chemicals. [ABSTRACT FROM AUTHOR]

The use of biomass-based glycerol to produce chemicals with high added value is of great significance for solving the problem of glycerol surplus and thus reducing the production cost of biodiesel. The production of 1,2-propanediol (abbreviated as 1,2-PDO) and 1,3-propanediol (abbreviated as 1,3-PDO) via the hydrogenolysis of glycerol is one of the most representative and highest-potential processes for the comprehensive utilization of biomass-based glycerol. Glycerol hydrogenolysis may include several parallel and serial reactions (involving broken C–O and C–C bonds), and therefore, the catalyst is a key factor in improving the rate of glycerol hydrogenolysis and the selectivities of the target products. Over the past 20 years, glycerol hydrogenolysis has been extensively investigated, and until now, the developments of catalysts for glycerol hydrogenolysis have been active research topics. Non-precious metals, including Cu, Ni, and Co, and some precious metals (Ru, Pd, etc.) have been used as the active components of the catalysts for the hydrogenolysis of glycerol to 1,2-PDO, while precious metals such as Pt, Rh, Ru, Pd, and Ir have been used for the catalytic conversion of glycerol to 1,3-PDO. In this article, we focus on reviewing the research progress of the catalyst systems, including Cu-based catalysts and Pt-, Ru-, and Pd-based catalysts for the hydrogenolysis of glycerol to 1,2-PDO, as well as Pt-WOx-based and Ir-ReOx-based catalysts for the hydrogenolysis of glycerol to 1,3-PDO. The influence of the properties of active components and supports, the effects of promoters and additives, and the interaction and synergic effects between active component metals and supports are also examined. [ABSTRACT FROM AUTHOR]

A one-pot, one-step protocol combining hydrogen transfer initiated dehydration (HTID) of 1,3-propanediol (1,3-PDO), catalysed by [Cp*IrCl2(NHC)] (Cp* = pentamethylcyclopentadienyl; NHC = carbene ligand) complexes (1-5H and 1-3F), and self-aldol condensation (SAC) of propanal (2), allowed selective production of C6 aldehyde 2-methyl-pent-2-enal (3), in ionic liquids with high substrate conversion. This shows, for the first time, the conversion of 1,3-propanediol to C6 aldehydes in one pot via a catalytic hydrogen borrowing methodology. The Ir(III) pre-catalysts and the ionic liquids were recyclable. C6 aldehyde 2-methyl-pent-2-enal could also be selectively produced in the presence of water and in neat 1,3-PDO. The efficient, selective delivery of a value-added chemical from 1,3-PDO, a major product of many whole-cell bacterial fermentation processes, shows that the combination of chemo-catalytic processing of the chemical platform via Cp*IrCl2(NHC)-catalysed HTID/SAC with bio-catalysis has the potential to allow direct valorisation of the bio-renewable feedstocks, such as waste glycerol and sugars, into valuable chemicals.

The individual ingredients of 1,3-Propanediol, Soline, and Fucocert® (PSF) are often used as cosmetic formulations in skin care. In addition, the mixture of Lecigel, Cetiol®CC, Activonol-6, and Activonol-M (LCAA) is often used as a cosmetic base. However, whether the combination of LCAA with PSF (LCAA-PSF) exerts a therapeutic effect on psoriasis remains unclear. In this study, mice induced with imiquimod (IMQ) were divided into three groups and administered 100 mg/day of LCAA, 100 mg/day of LCAA-PSF, or Vaseline on the dorsal skin of each mouse. Weight-matched mice treated with Vaseline alone were used as controls. Hematoxylin and eosin (H&E) staining and enzyme-linked immunosorbent assay(ELISA) were used to assess tissue morphology and inflammatory cytokines. RNA sequencing analysis was used to predict the mechanism underlying the action of LCAA-PSF against psoriasis, while immunohistochemical analysis validation was used to identify pertinent molecular pathways. The results demonstrated that LCAA-PSF alleviated IMQ-induced keratinocyte differentiation/ proliferation bydecreasingthe serum levels of inflammatory cytokines such as IL-6, TNF-α, IL-23, and IL-17A and the epidermisof TGFβ, Ki67, CK5/6, and VEGF expression, which is associated with angiogenesis and keratinocyte differentiation/ proliferation. These findings highlight the antipsoriatic activity of LCAA-PSF in a psoriasis-like mouse model and suggest this may occurvia the inhibition of inflammatory factor secretionand the TGFβ-related signal pathway.

The adverse effects of climate change, predominantly propelled by greenhouse gas emissions from fossil fuels, underscore the urgency of seeking sustainable alternatives to fossil fuel use. Amid growing concerns about climate change caused by fossil fuels and petrochemicals, this review focuses on sustainable solutions through the conversion of glycerol into value-added biochemicals. Glycerol, as the main byproduct of biodiesel production, is a particularly attractive chemical due to its potential to be upgraded into value-added building blocks and biochemicals. This review provides a detailed analysis of different thermochemical (catalytic) and synthetic biology (fermentative) pathways for the conversion of glycerol into 1,2-propanediol and 1,3-propanediol, which have proven industrial and commercial applications globally. The synthesis of propanediol from glycerol hydrogenolysis and other catalytic processes using different active metals and acidic oxides is reviewed. The reaction mechanism involved in hydrogenolysis reactions concerning the surface reaction mechanism is systematically discussed. The metabolic activities of promising microorganisms in fermenting glycerol, as the carbon source used to produce propanediol, are illustrated and elaborated. Combining these insights, this review is a comprehensive resource that can foster a better understanding of glycerol transformation into propanediol and its implications for sustainable chemistry and industrial practices. This exploration of alternative methods emphasizes the potential of sustainable approaches to reshape production practices and contribute to climate change mitigation. [ABSTRACT FROM AUTHOR]

The self‐administration of nicotine using e‐cigarettes involves the use of liquids containing both solvent and aroma. The vaping appeal is enhanced by the sensory perception of flavours. Thus, an important attention may be paid to the choice of the refill liquid. For this purpose, this study aimed to evaluate the potential of 1,3‐propanediol (PDO, vegetal solvent) and 1,3‐butanediol (BDO, vegetal solvent), in replacing the chemical one such 1,2‐propanediol (PG) while maintaining sensory pleasure and ensuring the wellbeing. The work was conducted with 30 participants accustomed to vaping. Three flavours have been selected, menthol, vanillin and pyrazine, respectively, to provide the most preferred perceptions which are respectively mint, sweet and tobacco. The Rate‐All‐That‐Apply (RATA) method was chosen since it is rapid and robust. Menthol/PDO and menthol/PG exhibited a close olfactive profile, described as minty, cold and sweet. A similar finding has been observed for vanillin/PDO and vanillin/PG. The use of BDO provided different perceptions in comparison with PDO and PG regardless of the type of flavour. It was found to be the most suitable for pyrazine perception. These results were enhanced by the application of the agglomerative hierarchical clustering (AHC). The obtained dendrogram was composed of three groups according to their similarities, where e‐liquids containing PDO, and PG belongs to the same groups for both menthol and vanillin. [ABSTRACT FROM AUTHOR]

Long-term operation of four in-series horizontal anaerobic reactors with fixed bed (HARFB) R1, R2, R3, and R4 was conducted to evaluate the co-digestion of domestic sewage (DS) with different proportions of crude glycerol (CG) from biodiesel production. The main objective was to examine the effect of the increase of CG in the influent with the proportions of 1.5%, 2%, and 3% (v/v). The anaerobic co-digestion was conducted in sequential reactors with increasing diameters to favor the fermentation in the R1 and R2 and the methanogenesis in the R3 and R4. The increase in CG proportions in the influent resulted in mean OLRs of 18.06, 26.75, and 37.85 kg COD/(m3 day) for 1.5%, 2%, and 3% of CG, respectively. The highest hydrogen production was (L H2 /(m3 day)) 277.88 (R1, at the 1.5% CG) and 84.43 (R2, at the 2% CG). The highest methane volumetric production occurred during the 1.5% CG in R3 (306.7 L CH4/(m3 day)), with a 98% COD removal. The configuration of four in-series reactors could promote total removals of CG, even at the 3% CG. Reactor R1 produced 4 g/L of 1,3-propanediol and 2.8 g/L of propionic acid. The changes in the microbiota were verified, mainly on how the Lactobacillales and Selenomonadales orders were favored, respectively, in the fermentative reactor (R1) and the methanogenic reactor (R3). The inhibition of the methanogens verified in the in-series reactors selected the Methanosarcinales order. Even though CG increased caused some instabilities in the reactor parameters, no toxic effect was reached and the HARFB in-series system showed robustness to removing CG continuously for extended times. [ABSTRACT FROM AUTHOR]

Although 1,3-propanediol (1,3-PD) is usually considered an anaerobic fermentation product from glycerol by Klebsiella pneumoniae, microaerobic conditions proved to be more conducive to 1,3-PD production. In this study, a genome-scale metabolic model (GSMM) specific to K. pneumoniae KG2, a high 1.3-PD producer, was constructed. The iZY1242 model contains 2090 reactions, 1242 genes and 1433 metabolites. The model was not only able to accurately characterise cell growth, but also accurately simulate the fed-batch 1,3-PD fermentation process. Flux balance analyses by iZY1242 was performed to dissect the mechanism of stimulated 1,3-PD production under microaerobic conditions, and the maximum yield of 1,3-PD on glycerol was 0.83 mol/mol under optimal microaerobic conditions. Combined with experimental data, the iZY1242 model is a useful tool for establishing the best conditions for microaeration fermentation to produce 1,3-PD from glycerol in K. pneumoniae. [ABSTRACT FROM AUTHOR]

The deactivation of Pt/WOx/Al2O3 and Pt-Ru/WOx/Al2O3 catalysts in the glycerol hydrogenolysis to 1,3-propanediol (1,3-PDO) was investigated in autoclave. The selectivity of both catalysts toward 1,3-PDO was within 50–56% after the first five usages at 170 °C for 12 h with a H2 pressure of 9 MPa. With Pt/WOx/Al2O3, the conversion of glycerol decreased from 44.3% (1st reaction) to 27.2% (5th reaction), whereas a conversion of 52.4%, 48.0%, and 48.4% was obtained in the 1st, 5th, and 20th reactions, respectively, when Pt-Ru/WOx/Al2O3 was used. The characterizations of the catalysts showed that the pore structure of the catalyst changed because of the crystal structure of the catalyst support changing from γ-Al2O3 to pseudo-boehmite. However, the changes of the catalyst morphology were not responsible for the catalyst deactivation. Simultaneously, the acidity of catalysts was not shown to be a factor in their deactivation. On the other side, catalysts were not deactivated as a result of the loss of active components. Catalyst deactivation during glycerol hydrogenolysis was finally caused by the aggregation of active metal particles (Pt or Pt-Ru). [ABSTRACT FROM AUTHOR]

The H2O–3-amino-1-propanol (3AP) system at 300 K was studied by molecular dynamics, graph theory, and Delaunay simplex methods. All the molecules were shown to be bound into a three-dimensional network of hydrogen bonds over the entire range of concentrations in the system. The characteristics of the networks and their concentration dependences were determined. The frequency at which the environment of molecules changes is discussed. The results were compared with those for mixed networks in aqueous solutions of 1,3-propanediol and monoethanolamine. [ABSTRACT FROM AUTHOR]

Abstract Extractive adsorption is an integrated separation method employing a novel resin with both particle and liquid characteristics in terms of adsorption and extraction. In this study, the novel extractive adsorption polystyrene-divinylbenzene (PS-DVB) macroporous resin was synthesized by suspension polymerization, in which n-octanol (OL-PS-DVB) or mixed alcohols of n-octanol, undecyl alcohol, and tetradecyl alcohol (MA-PS-DVB) were added as porogen and enclosed in the resin skeleton after the reaction. The characterization of the two novel resins of OL-PS-DVB and MA-PS-DVB showed that they have large specific surface areas of 48.7 and 17.4 m2/g, respectively. Additionally, the two synthesized resins have much higher static adsorption capacities of 1,3-propanediol (511 and 473 mg/g) and dynamic adsorption capacities (312 and 267 mg/g) than traditional resins, because extractants enclosed in the resin can increase the adsorption capacity. Through Langmuir equation, the theoretical static maximum adsorption capacity of the mixed alcohols resin is 515 mg/g at 298 K and Gibbs free energy change of adsorption was -3781 J/mol, indicating that the adsorption process was spontaneous. In addition, the sorbent concentration effect in the resin was generated at high 1,3-propanediol (1,3-PDO) concentrations. The fitting of the Flocculation model can reveal that there is a possible relation between adsorption and flocculation. Compared to OL-PS-DVB, MA-PS-DVB showed better performance in the recovery yield of 1,3-PDO and other byproducts, the removal rates of the inorganic salt and protein, and the efficiency of recycled resin. For MA-PS-DVB, the recovery of 1,3-PDO, butyrate acid, acetic acid, and residual glycerol was 97.1%, 94.7%, 93.3%, and 90.3%, respectively. Simultaneously, the resin of MA-PS-DVB could remove 93.8% of inorganic salts and 90.9% of proteins in the concentrated fermentation broth. The two synthesized resins of OL-PS-DVB and MA-PS-DVB still had 90% or 92% of capacity for extractive adsorption of 1,3-propanediol after 10 times of recycling, which exhibited potential application in the separation of 1,3-propanediol from fermentation broth.

Abstract Background 1,3-Propanediol (1,3-PDO) is a platform compound, which has been widely used in food, pharmaceutical and cosmetic industries. Compared with chemical methods, the biological synthesis of 1,3-PDO has shown promising applications owing to its mild conditions and environmental friendliness. However, the biological synthesis of 1,3-PDO still has the problem of low titer and yield due to the shortage of reducing powers. Results In this study, Klebsiella sp. strain YT7 was successfully isolated, which can synthesize 11.30 g/L of 1,3-PDO from glycerol in flasks. The intracellular redox regulation strategy based on the addition of electron mediators can increase the 1,3-PDO titer to 28.01 g/L. Furthermore, a co-culturing system consisting of strain YT7 and Shewanella oneidensis MR-1 was established, which can eliminate the supplementation of exogenous electron mediators and reduce the by-products accumulation. The 1,3-PDO yield reached 0.44 g/g and the final titer reached 62.90 g/L. The increased titer and yield were attributed to the increased redox levels and the consumption of by-products. Conclusions A two-bacterium co-culture system with Klebsiella sp. strain YT7 and S. oneidensis strain MR-1 was established, which realized the substitution of exogenous electron mediators and the reduction of by-product accumulation. Results provided theoretical basis for the high titer of 1,3-PDO production with low by-product concentration.

[Display omitted] • Glycerol C-O cleavage via protonation dehydration mechanism at reaction condition. • Brønsted acid generated in-situ by H spill over from Pt to WO x across Pt-WO x interface. • Primary/secondary C-O cleavage: linear/non-monotonic relation with NH 3 binding. • Brønsted acid strength is a descriptor for catalyst activity and selectivity. • Increasing strong Brønsted acid sites likely to enhance 1,3-PDO yield. DFT simulations predicted the C-O bond cleavage in glycerol on Brønsted acidic Pt-WO x catalyst under a hydrogen atmosphere to be via a "protonation dehydration" mechanism. Interfacial Pt-WO x sites facilitate Brønsted acid (BA) site formation by hydrogen spillover and synergistic activity of Pt and WO x. At strong BA sites, selective formation of 1,3-PDO is likely due to the large difference of over 40 kJ/mol in primary and secondary C-O bond cleavage barriers. The secondary C-O bond cleavage has a linear relation with NH 3 binding energy while there is a non-monotonic trend for the primary C-O cleavage. Hence, Brønsted acid strength is a potential descriptor for the catalyst activity and 1,3-PDO selectivity. Synthetic strategies enabling fine dispersion of WO x to trimeric units on the Pt nanoparticles, while preventing W doping and agglomeration of WO x to 3D WO 3 on small Pt nanoparticles are desirable for high BA strength and thereby 1,3-PDO yield. [ABSTRACT FROM AUTHOR]

The ability of some bacteria to perform Extracellular Electron Transfer (EET) has been explored in bioelectrochemical systems (BES) to obtain energy or chemicals from pure substances or residual substrates. Here, a new pyoverdine-producing Pseudomonas aeruginosa strain was isolated from an MFC biofilm oxidizing glycerol, a by-product of biodiesel production. Strain EL14 was investigated to assess its electrogenic ability and products. In an open circuit system (fermentation system), EL14 was able to consume glycerol and produce 1,3-propanediol, an unusual product from glycerol oxidation in P. aeruginosa. The microbial fuel cell (MFC) EL14 reached a current density of 82.4 mA m−2 during the first feeding cycle, then dropped sharply as the biofilm fell off. Cyclic voltammetry suggests that electron transfer to the anode occurs indirectly, i.e., through a redox substance, with redox peak at 0.22 V (vs Ag/AgCl), and directly probably by membrane redox proteins, with redox peak at 0.05 V (vs Ag/AgCl). EL14 produced added-value bioproducts, acetic and butyric acids, as well as 1,3 propanediol, in both fermentative and anodic conditions. However, the yield of 1,3-PDO from glycerol was enhanced from 0.57 to 0.89 (mol of 1,3-PDO mol−1 of glycerol) under MFC conditions compared to fermentation. This result was unexpected, since successful 1,3-PDO production is not usually associated with P. aeruginosa glycerol metabolism. By comparing EL14 genomic sequences related to the 1,3-PDO biosynthesis with P. aeruginosa reference strains, we observed that strain EL14 has three copies of the dhaT gene (1,3-propanediol dehydrogenase a different arrangement compared to other Pseudomonas isolates). Thus, this work functionally characterizes a bacterium never before associated with 1,3-PDO biosynthesis, indicating its potential for converting a by-product of the biodiesel industry into an emerging chemical product. [ABSTRACT FROM AUTHOR]

BACKGROUND: Previously, Escherichia coli NSK015 was developed for high yield of 1,3‐propanediol (1,3‐PDO) production. To further improve 1,3‐PDO concentration, parameters including kLa values with different agitations and impeller numbers, concentrations of coenzyme B12 and feeding strategies during fed‐batch fermentation were investigated. RESULTS: In this study, aerobic conditions at 300 rpm agitation and 1 vvm aeration with two Rushton turbine impellers (kLa = 33.6 h−1) and the concentration of coenzyme B12 at 7.5 μmol L−1 were identified as the best optimized conditions to improve 1,3‐PDO production by the strain. With a two‐pulsed continuous feeding, E. coli NSK015 produced 1,3‐PDO up to 60.3 g L−1 with the 1,3‐PDO yield approaching a theoretical maximum of 0.97 g g−1 and productivity of 0.42 g L−1 h−1 in fed‐batch fermentation, in which concentration was improved about 60% compared to that of batch fermentation. CONCLUSION: The result indicated the efficiency of E. coli NSK015 in producing 1,3‐PDO under optimal aerobic conditions. The strain could even enhance growth and maintain enzymatic activities involved in the 1,3‐PDO pathway without utilizing antibiotics, isopropyl β‐d‐1‐thiogalactopyranoside (IPTG) or enriching nutrients. Plasmid instability, high production cost related to medium preparation and purification, and waste disposal were not of concern. This may provide a new insight for large‐scale 1,3‐PDO production by E. coli NSK015. Additionally, E. coli NSK015 could be a microbial host model for further developing new 1,3‐PDO‐producing microorganisms regardless of plasmid, inducer, antibiotics and rich nutrients in fermentation medium. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Abstract Background Climate change caused by greenhouse gas emission has become a global hot topic. Although biotechnology is considered as an environmentally friendly method to produce chemicals, almost all biochemicals face carbon dioxide emission from inevitable respiration and energy metabolism of most microorganisms. To cater for the broad prospect of biochemicals, bioprocess optimization of diverse valuable products is becoming increasingly important for environmental sustainability and cleaner production. Based on Ca(OH)2 as a CO2 capture agent and pH regulator, a bioprocess was proposed for co-production of 1,3-propanediol (1,3-PDO), biohydrogen and micro-nano CaCO3 by Clostridium butyricum DL07. Results In fed-batch fermentation, the maximum concentration of 1,3-PDO reached up to 88.6 g/L with an overall productivity of 5.54 g/L/h. This productivity is 31.9% higher than the highest value previously reports (4.20 g/L/h). In addition, the ratio of H2 to CO2 in exhaust gas showed a remarkable 152-fold increase in the 5 M Ca(OH)2 group compared to 5 M NaOH as the CO2 capture agent. Green hydrogen in exhaust gas ranged between 17.2% and 20.2%, with the remainder being N2 with negligible CO2 emissions. During CO2 capture in situ, micro-nano calcite particles of CaCO3 with sizes in the range of 300 nm to 20 µm were formed simultaneously. Moreover, when compared with 5M NaOH group, the concentrations of soluble salts and proteins in the fermentation broth of 5 M Ca(OH)2 group were notably reduced by 53.6% and 44.1%, respectively. The remarkable reduction of soluble salts and proteins would contribute to the separation of 1,3-PDO. Conclusions Ca(OH)2 was used as a CO2 capture agent and pH regulator in this study to promote the production of 1,3-PDO. Meanwhile, micro-nano CaCO3 and green H2 were co-produced. In addition, the soluble salts and proteins in the fermentation broth were significantly reduced. Graphical Abstract

Extractive adsorption is an integrated separation method employing a novel resin with both particle and liquid characteristics in terms of adsorption and extraction. In this study, the novel extractive adsorption polystyrene-divinylbenzene (PS-DVB) macroporous resin was synthesized by suspension polymerization, in which n-octanol (OL-PS-DVB) or mixed alcohols of n-octanol, undecyl alcohol, and tetradecyl alcohol (MA-PS-DVB) were added as porogen and enclosed in the resin skeleton after the reaction. The characterization of the two novel resins of OL-PS-DVB and MA-PS-DVB showed that they have large specific surface areas of 48.7 and 17.4 m2/g, respectively. Additionally, the two synthesized resins have much higher static adsorption capacities of 1,3-propanediol (511 and 473 mg/g) and dynamic adsorption capacities (312 and 267 mg/g) than traditional resins, because extractants enclosed in the resin can increase the adsorption capacity. Through Langmuir equation, the theoretical static maximum adsorption capacity of the mixed alcohols resin is 515 mg/g at 298 K and Gibbs free energy change of adsorption was -3781 J/mol, indicating that the adsorption process was spontaneous. In addition, the sorbent concentration effect in the resin was generated at high 1,3-propanediol (1,3-PDO) concentrations. The fitting of the Flocculation model can reveal that there is a possible relation between adsorption and flocculation. Compared to OL-PS-DVB, MA-PS-DVB showed better performance in the recovery yield of 1,3-PDO and other byproducts, the removal rates of the inorganic salt and protein, and the efficiency of recycled resin. For MA-PS-DVB, the recovery of 1,3-PDO, butyrate acid, acetic acid, and residual glycerol was 97.1%, 94.7%, 93.3%, and 90.3%, respectively. Simultaneously, the resin of MA-PS-DVB could remove 93.8% of inorganic salts and 90.9% of proteins in the concentrated fermentation broth. The two synthesized resins of OL-PS-DVB and MA-PS-DVB still had 90% or 92% of capacity for extractive adsorption of 1,3-propanediol after 10 times of recycling, which exhibited potential application in the separation of 1,3-propanediol from fermentation broth. Highlights: The novel extractive adsorption PS-DVB macroporous resin was synthesized The structure of the synthesized resins was characterized The static and dynamic adsorption behavior of synthesized resins was investigated The sorbent concentration effect was generated at high 1,3-PDO concentrations Synthesized resins showed excellent performance in separation 1,3-PDO from broth [ABSTRACT FROM AUTHOR]

In this study, we show how electrochemically mediated bioconversion can greatly increase the co-production of 1,3-propanediol and organic acids from glycerol in an industrial bioprocess using a Clostridum pasteurianum mutant. Remarkably, an enhanced butyrate formation was observed due to a weakened butanol pathway of the mutant. This allowed the strain to have a higher ATP generation for an enhanced growth, higher glycerol consumption and PDO production. The PDO titer reached as high as 120.67 g/L at a cathodic current of -400 mA, which is 33% higher than that without electricity, with a concurrent increase of butyric acid by 80%. To fully recover the increased PDO and organic acids, a novel downstream process combining thin film evaporation of PDO and esterification of organic acids with ethanol was developed. This enables the efficient co-production of PDO, ethyl acetate and ethyl butyrate with a high overall carbon use of 87%. [ABSTRACT FROM AUTHOR]

Background: 1,3-Propanediol (1,3-PDO) is a platform compound, which has been widely used in food, pharmaceutical and cosmetic industries. Compared with chemical methods, the biological synthesis of 1,3-PDO has shown promising applications owing to its mild conditions and environmental friendliness. However, the biological synthesis of 1,3-PDO still has the problem of low titer and yield due to the shortage of reducing powers. Results: In this study, Klebsiella sp. strain YT7 was successfully isolated, which can synthesize 11.30 g/L of 1,3-PDO from glycerol in flasks. The intracellular redox regulation strategy based on the addition of electron mediators can increase the 1,3-PDO titer to 28.01 g/L. Furthermore, a co-culturing system consisting of strain YT7 and Shewanella oneidensis MR-1 was established, which can eliminate the supplementation of exogenous electron mediators and reduce the by-products accumulation. The 1,3-PDO yield reached 0.44 g/g and the final titer reached 62.90 g/L. The increased titer and yield were attributed to the increased redox levels and the consumption of by-products. Conclusions: A two-bacterium co-culture system with Klebsiella sp. strain YT7 and S. oneidensis strain MR-1 was established, which realized the substitution of exogenous electron mediators and the reduction of by-product accumulation. Results provided theoretical basis for the high titer of 1,3-PDO production with low by-product concentration. [ABSTRACT FROM AUTHOR]

The effects of propanol and 1, 3-propanediol on fatty acid and biomass accumulation in Schizochytrium ATCC 20888 were explored. Propanol increased the contents of saturated fatty acids and total fatty acids by 55.4 and15.3%, while 1, 3-propanediol elevated the polyunsaturated fatty acids, total fatty acids and biomass contents by 30.7, 17.0, and 6.89%. Although both of them quench ROS to increase fatty acids biosynthesis, the mechanisms are different. The effect of propanol did not reflect on metabolic level while 1, 3-propanediol elevated osmoregulators contents and activated triacylglycerol biosynthetic pathway. The triacylglycerol content and the ratio of polyunsaturated fatty acids to saturated fatty acids were significantly increased by 2.53-fold, which explained the higher PUFA accumulation in Schizochytrium after adding 1, 3- propanediol. At last, the combination of propanol and 1, 3-propanediol further elevated total fatty acids by approximately 1.2-fold without compromising cell growth. These findings are valuable for scale-up production of designed Schizochytrium oil for various application purposes. [ABSTRACT FROM AUTHOR]

1,3-propanediol (1,3-PD) has a wide range of industrial applications. The most studied natural producers capable of fermenting glycerol to 1,3-PD belong to the genera Klebsiella, Citrobacter, and Clostridium. In this study, the optimization of medium composition for the biosynthesis of 1,3-PD by Citrobacter freundii AD119 was performed using the one-factor-at-a-time method (OFAT) and a two-step statistical experimental design. Eleven mineral components were tested for their impact on the process using the Plackett–Burman design. MgSO4 and CoCl2 were found to have the most pronounced effect. Consequently, a central composite design was used to optimize the concentration of these mineral components. Besides minerals, carbon and nitrogen sources were also optimized. Partial glycerol substitution with other carbon sources was found not to improve the bioconversion process. Moreover, although yeast extract was found to be the best nitrogen source, it was possible to replace it in part with (NH4)2SO4 without a negative impact on 1,3-PD production. As a part of the optimization procedure, an artificial neural network model of the growth of C. freundii and 1,3-PD production was developed as a predictive tool supporting the design and control of the bioprocess under study. [ABSTRACT FROM AUTHOR]