Efficient hydrogenation of diethyl malonate to 1,3-propanediol over CuGa/SiO2 bimetallic catalysts.

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.

Reaction of KHP with excess NaOH or TRIS as standard reactions for calibration of titration calorimeters from 0 to 60 °C.

Calibration of titration calorimeters is an ongoing problem, particularly with calorimeters with reaction vessel volumes < 10 mL in which an electrical calibration heater is positioned outside the calorimetric vessel. Consequently, a chemical reaction with a known enthalpy change must be used to accurately calibrate these calorimeters. This work proposes the use of standard solutions of potassium acid phthalate (KHP) titrated into solutions of excess sodium hydroxide (NaOH) or excess tris(hydroxymethyl)aminomethane (TRIS) as standard reactions to determine the collective accuracy of the relevant variables in a determination of the molar enthalpy change for a reaction. KHP is readily available in high purity, weighable for easy preparation of solutions with accurately known concentrations, stable in solution, not compromised by side reactions with common contaminants such as atmospheric CO2, and non-corrosive to materials used in calorimeter construction. Molar enthalpy changes for these reactions were calculated from 0 to 60 °C from reliable literature data for the pKa of KHP, the molar enthalpy change for protonation of TRIS, and the molar enthalpy change for ionization of water. The feasibility of using these reactions as enthalpic standards was tested in several calorimeters; a 50 mL CSC 4300, a 185 µL NanoITC, a 1.4 mL VP-ITC, and a TAM III with 1 mL reaction vessels. The results from the 50 mL CSC 4300, which was accurately calibrated with an electric heater, verified the accuracy of the calculated standard values for the molar enthalpy changes of the proposed reactions.

Kinetics-based development of two-stage continuous fermentation of 1,3-propanediol from crude glycerol by Clostridium butyricum.

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.

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.

Safety Assessment of Alkane Diols as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 10 alkane diol ingredients as used in cosmetics. The alkane diols are structurally related to each other as small diols, and most are reported to function in cosmetics as solvents. The Panel reviewed the relevant data for these ingredients, and concluded that seven alkane diols are safe in cosmetics in the present practices of use and concentration described in this safety assessment, but that the available data are insufficient to make a determination of safety for three ingredients, namely 1,4-Butanediol, 2,3-Butanediol, and Octanediol.

Dynamic flux balance analysis of 1,3-propanediol production by clostridium butyricum fermentation.

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.

Biological Activity of Poly(1,3-propanediol citrate) Films and Nonwovens: Mechanical, Thermal, Antimicrobial, and Cytotoxicity Studies.

Polymers are of great interest for medical and cosmeceutical applications. The current trend is to combine materials of natural and synthetic origin in order to obtain products with appropriate mechanical strength and good biocompatibility, additionally biodegradable and bioresorbable. Citric acid, being an important metabolite, is an interesting substance for the synthesis of materials for biomedical applications. Due to the high functionality of the molecule, it is commonly used in biomaterials chemistry as a crosslinking agent. Among citric acid-based biopolyesters, poly(1,8-octanediol citrate) is the best known. It shows application potential in soft tissue engineering. This work focuses on a much less studied polyester, poly(1,3-propanediol citrate). Porous and non-porous materials based on the synthesized polyesters are prepared and characterized, including mechanical, thermal, and surface properties, morphology, and degradation. The main focus is on assessing the biocompatibility and antimicrobial properties of the materials.

Recent Progress in Catalyst Development of the Hydrogenolysis of Biomass-Based Glycerol into Propanediols-A Review.

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.

One versus two-stage codigestion of sugarcane vinasse and glycerol: Assessing combinations at mesophilic and (hyper) thermophilic conditions.

Sugarcane vinasse exits the distillation process at high temperatures, which may differ from the optimal temperatures for dark fermentation and anaerobic digestion. A 15 °C temperature increase, for example, stops sugarcane vinasse methane generation, making distillery vinasse digestion complicated. Conversely, in other aspects, co-digesting vinasse and glycerol has been proven to stabilize methane production from vinasse because of sulfate dilution. However, glycerol has not been tested to stabilize vinasse digestion under temperature changes. Thus, this study compared the effects of different temperature settings on the co-digestion of 10 g COD L-1 of vinasse and glycerol (50 %:50 % on a COD basis) in anaerobic fluidized bed reactors (AFBR), i.e., an acidogenic and a methanogenic one-stage AFBRs operated at 55, 60, and 65 °C, and two methanogenic AFBRs fed both with acidogenic effluent (one operated at room temperature (25 °C) and the other at 55, 60, and 65 °C). The co-digestion provided steady methane generation at all AFBRs, with methane production rates ranging from 2.27 to 2.93 L CH4 d-1 L-1, whether in one or two stages. A feature of this research was to unravel the black box of the role of sulfate in the digestion of sugarcane vinasse, which was rarely studied. Desulfovibrio was the primary genus degrading 1,3-propanediol into 3-hydroxypropanoate after genome sequencing. Phosphate acetyltransferase (EC: 2.3.1.8, K00625) and acetate kinase (EC: 2.7.2.1, K00925) genes were also found, suggesting propionate was metabolized. In practical aspects, regarding the two-stage systems, the thermophilic-mesophilic (acidogenic-methanogenic) configuration is best for extracting additional value-added products because 1,3-propanediol may be recovered at high yields with steady methane production at reduced energy expenditure in a reactor operated at room temperature. However, the one-stage design is best for methane generation per system volume since it remained stable with rising temperatures, and all systems presented similar methane production rates.

Pt-Loaded Nb─W Metal Composite Oxide for Selective Cleavage of Secondary C─O Bonds.

Selective hydrogenolysis of glycerol to 1,3-propanediol (1,3-PDO) is recognized as one of the most promising reactions for the valorization of biomass. Precise activation of C─O bonds of glycerol molecule is the key step to realize the high yield of catalytic conversion. Here, a Pt-loaded Nb-W composite oxides with crystallographic shear phase for the precise activation and cleavage of secondary C─O (C(2)─O) bonds are first reported. The developed Nb14 W3 O44 with uniform structure possesses arrays of W-O-Nb active sites that totally distinct from individual WOx or NbOx species, which is superior to the adsorption and activation of C(2)─O bonds. The Nb14 W3 O44 support with rich reversible redox couples also promotes the electron feedback ability of Pt and enhances its interaction with Pt nanoparticles, resulting in high activity for H2 dissociation and hydrogenation. All these favorable factors confer the Pt/Nb14 W3 O44 excellent performance for selective hydrogenolysis of glycerol to 1,3-PDO with the yield of 75.2% exceeding the record of 66%, paying the way for the commercial development of biomass conversion. The reported catalysts or approach can also be adopted to create a family of Nb-W metal composite oxides for other catalytic reactions requiring selective C─O bond activation and cleavage.

Enhancing 1,3-Propanediol Productivity in the Non-Model Chassis Clostridium beijerinckii through Genetic Manipulation.

Biotechnological processes at biorefineries are considered one of the most attractive alternatives for valorizing biomasses by converting them into bioproducts, biofuels, and bioenergy. For example, biodiesel can be obtained from oils and grease but generates glycerol as a byproduct. Glycerol recycling has been studied in several bioprocesses, with one of them being its conversion to 1,3-propanediol (1,3-PDO) by Clostridium. Clostridium beijerinckii is particularly interesting because it can produce a range of industrially relevant chemicals, including solvents and organic acids, and it is non-pathogenic. However, while Clostridium species have many potential advantages as chassis for synthetic biology applications, there are significant limitations when considering their use, such as their limited genetic tools, slow growth rate, and oxygen sensitivity. In this work, we carried out the overexpression of the genes involved in the synthesis of 1,3-PDO in C. beijerinckii Br21, which allowed us to increase the 1,3-PDO productivity in this strain. Thus, this study contributed to a better understanding of the metabolic pathways of glycerol conversion to 1,3-PDO by a C. beijerinckii isolate. Also, it made it possible to establish a transformation method of a modular vector in this strain, therefore expanding the limited genetic tools available for this bacterium, which is highly relevant in biotechnological applications.

A genome-scale metabolic model of the effect of dissolved oxygen on 1,3-propanediol fermentation by Klebsiella pneumoniae.

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.

Biosynthesis of 1,3-Propanediol via a New Pathway from Glucose in Escherichia coli.

1,3-Propanediol (1,3-PDO), an important dihydric alcohol, is widely used in textiles, resins, and pharmaceuticals. More importantly, it can be used as a monomer in the synthesis of polytrimethylene terephthalate (PTT). In this study, a new biosynthetic pathway is proposed to produce 1,3-PDO using glucose as a substrate and l-aspartate as a precursor without the addition of expensive vitamin B12. We introduced a 3-HP synthesis module derived from l-aspartate and a 1,3-PDO synthesis module to achieve the de novo biosynthesis. The following strategies were then pursued that included screening key enzymes, optimizing the transcription and translation levels, enhancing the precursor supply of l-aspartate and oxaloacetate, weakening the tricarboxylic acid (TCA) cycle, and blocking competitive pathways. We also used transcriptomic methods to analyze the different gene expression levels. Finally, an engineered Escherichia coli strain produced 6.41 g/L 1,3-PDO with a yield of 0.51 mol/mol glucose in a shake flask and 11.21 g/L in fed-batch fermentation. This study provides a new pathway for production of 1,3-PDO.

Process engineering towards an oxidative cellular state improves 3-hydroxypropionic acid production with Lentilactobacillus diolivorans.

3-hydroxypropionic acid (3-HP) is among the top platform chemicals proposed for bio based production by microbial fermentation from renewable resources. A promising renewable substrate for 3-HP production is crude glycerol. Only a few microorganisms can efficiently convert glycerol to 3-HP. Among the most promising organisms is Lentilactobacillus diolivorans. In this study, an already established fed-batch process, accumulating 28 g/L 3-HP, was used as a starting point for process engineering. The engineering approaches focused on modulating the cellular redox household towards a more oxidized state, as these conditions favour 3-HP production. Variations of oxygen and glucose availability (controlled by the glucose/glycerol ratio in the feed medium) individually already improved 3-HP production. However, the combination of both optimal parameters (30% O2, 0.025 mol/mol glu/gly) led to the production of 67.7 g/L 3-HP after 180 h of cultivation, which is so far the highest titer reported for 3-HP production using Lactobacillus spp.

Heterologous 1,3-Propanediol Production Using Different Recombinant Clostridium beijerinckii DSM 6423 Strains.

1,3-propanediol (1,3-PDO) is a valuable basic chemical, especially in the polymer industry to produce polytrimethylene terephthalate. Unfortunately, the production of 1,3-PDO mainly depends on petroleum products as precursors. Furthermore, the chemical routes have significant disadvantages, such as environmental issues. An alternative is the biobased fermentation of 1,3-PDO from cheap glycerol. Clostridium beijerinckii DSM 6423 was originally reported to produce 1,3-PDO. However, this could not be confirmed, and a genome analysis revealed the loss of an essential gene. Thus, 1,3-PDO production was genetically reinstalled. Genes for 1,3-PDO production from Clostridium pasteurianum DSM 525 and Clostridium beijerinckii DSM 15410 (formerly Clostridium diolis) were introduced into C. beijerinckii DSM 6423 to enable 1,3-PDO production from glycerol. 1,3-PDO production by recombinant C. beijerinckii strains were investigated under different growth conditions. 1,3-PDO production was only observed for C. beijerinckii [pMTL83251_Ppta-ack_1,3-PDO.diolis], which harbors the genes of C. beijerinckii DSM 15410. By buffering the growth medium, production could be increased by 74%. Furthermore, the effect of four different promoters was analyzed. The use of the constitutive thlA promoter from Clostridium acetobutylicum led to a 167% increase in 1,3-PDO production compared to the initial recombinant approach.

Recent advances in metabolic engineering of microorganisms for the production of monomeric C3 and C4 chemical compounds.

Bio-based C3 and C4 bi-functional chemicals are useful monomers in biopolymer production. This review describes recent progresses in the biosynthesis of four such monomers as a hydroxy-carboxylic acid (3-hydroxypropionic acid), a dicarboxylic acid (succinic acid), and two diols (1,3-propanediol and 1,4-butanediol). The use of cheap carbon sources and the development of strains and processes for better product titer, rate and yield are presented. Challenges and future perspectives for (more) economical commercial production of these chemicals are also briefly discussed.

Enhanced 1,3-propanediol production with high yield from glycerol through a novel Klebsiella-Shewanella co-culture.

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.

Production of 1,3-propanediol using enzymatic hydrolysate derived from pretreated distillers' grains.

To minimize environmental pollution and waste of resources, distillers' grains (DG) was used to produce 1,3-propanediol. Biological, physical, and chemical methods were used for pretreatment. The correlation between features of pretreated samples and enzymatic digestibility was analyzed. The results showed that the glucan and xylan conversion of dilute sulfuric acid pretreated DG increased by 69.59% and 413.68%, respectively. The glucan conversion of microwave pretreated and xylan conversion of laccase pretreated DG increased by 14.22% and 34.19%, respectively. Pretreatment enhanced enzymatic digestibility through changing the dense structure and features of DG making them conductive to enzymatic hydrolysis. The production of 1,3-propanediol using enzymatic hydrolysate of pretreated DG and glycerol in shake-flask was 17 g/L. The utilization of DG not only provides plentiful raw materials replacing fossil fuels to produce biofuels and other chemicals but efficiently reduces environmental waste.

Optimization and Modeling of Citrobacter freundii AD119 Growth and 1,3-Propanediol Production Using Two-Step Statistical Experimental Design and Artificial Neural Networks.

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.

Electrochemically mediated bioconversion and integrated purification greatly enhanced co-production of 1,3-propanediol and organic acids from glycerol in an industrial bioprocess.

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%.