Propionic Acid Synthesis Research Articles

Biomanufacturing of propionic acid

Propionic acid as an important C3 platform chemical has been widely used in food, pharmaceutical, and chemical fields. The chemical synthesis of propionic acid from petroleum and other chemical products has serious environmental pollution and is not sustainable. In recent years, the production of propionic acid by microbial transformation of renewable resources has received extensive attention. Focusing on the biomanufacturing of propionic acid, this paper firstly reviews the studies about the metabolic engineering of Propionibacterium and the pathway reconstruction in heterogeneous hosts such as Escherichia coli and Saccharomyces cerevisiae. Secondly, this paper reviews the recent progress in the synthesis of high-purity propionic acid from L-threonine or bio-based 1, 2-propanediol by the design and modification of the pathway of Pseudomonas putida KT2440 based on synthetic biology.

Enhancing propionic acid production in the anaerobic fermentation of high-strength starch wastewater facilitated by hydraulic retention time and FeCl3 under alkaline pH

With increasing market demand, anaerobic fermentation for propionic acid production has been attracting lots of interests. However, oriented propionic acid refining in an open environment is typically challenging because of the diversity of microorganisms involved and the complexity of the process. This study examined the effects of varying the pH, FeCl3 dosage, and operational hydraulic retention time (HRT) on the synthesis of propionic acid from fermentative wastewater containing high-strength starch in an anaerobic sequencing batch reactor. The results showed that the most favorable operational conditions for the enrichment of propionic acid were an HRT of 24 h, and pH of 8.0 with a FeCl3 dosage of 960 mg/L. Under this condition, the long-term fermentation system produced a maximum of 7009 mg COD/L of propionic acid, which accounted for approximately 70.74 % of the total VFAs (volatile fatty acids). Microbial analysis showed that the combined regulating strategy not only significantly enriched genera associated with propionic acid production, such as norank_f__Propionibacteriaceae, Bacteroides, Corynebacterium, Bifidobacterium, but also shifted to lactate-propionate for production of propionic acid. These results will guide enhancing propionic acid products' yield from anaerobic fermentation.

Primer Design of Volatile Synthesis Coding Genes in Ralstonia syzygii subsp. celebesensis

Microbes produce various types of volatile organic compounds (VOCs) through metabolism, which can be used for diagnostic purposes. Microbes' types and classes of VOCs are very wide, including fatty acid derivatives (hydrocarbons, alcohols, and ketones), aromatic compounds, nitrogen-containing compounds, and volatile sulfur compounds. Microbial volatile organic compounds (VOCs) can also be divided into several chemical classes: alkenes, alcohols, ketones, benzos, pyrazines, sulfides, acids, esters, and terpenes. This study aimed to design primers for genes encoding volatile synthesis in Ralstonia syzygii subsp. celebesensis, which causes blood disease in the banana plant. Some of the genes involved are adc (acetone synthesis), adhP (ethanol synthesis), ilvA, nirBD (ammonia synthesis), mdcA (propionic acid synthesis), cysI (hydrogen sulfide synthesis), and speBC (putrescine synthesis). Primers were designed and examined for specificity in silico using Primer3Plus, Geneious Prime, and BLAST programs. The numbers of nine pairs designed primers were successfully amplifying the related nine VOC genes of R. syzygii subsp. celebesensis for qPCR.

The effectiveness of cobalt succinate in propylene glycol and glycerin composition to replenishment of energy demands for caws

As activators of digestive processes and energy metabolism, the possibility of using succinates, in particular cobalt succinate, is justified. This is a well-known drug in veterinary medicine and dairy farming.. The indication for its use is most often due to the perversion of appetite and not only. The fact is that cobalt chloride is part of the cobalamines-that is, vitamin B-12. Just with a deficiency of vitamin B-12, the synthesis of propionic acid, the main precursor of glucose formation, that is, energy, significantly worsens. In our experiments, cobalt succinate (succinic acid salt) was used in combination with feed energetics propylene glycol and glycerin. In the course of biochemical studies, it was found that this combination provides a well-pronounced clinical effect, qualitatively improves the metabolic function of the liver. This is indicated by the positive results of normalization of triglycerides, ketone bodies, transamination enzymes- AsAt and AlAt. Normalization of the reserve alkalinity index indicated that the energy exchange goes on without accumulation of problematic lactate and ketoacids substrates. It is quite obvious that this effect is achieved by activating the aerobic pathway of energy synthesis. Activation of the aerobic pathway of energy synthesis is the most effective approach to filling the energy deficit in the body. The aerobic energy synthesis pathway is 19 times more powerful than anaerobic glycolysis. As for the application of the development in production? Then here, everything is technologically simple, economically affordable, environmentally safe and absolutely harmless to the body of animals.

Electrochemical synthesis of propionic acid from reduction of ethanol and carbon dioxide at various applied potentials

The synthesis of value-added compounds other than acetate at high rates while utilizing cheap electrode materials is one of the current difficulties faced in microbial electrosynthesis. The present study investigated the production of higher chain volatile fatty acids from the reduction of ethanol and CO2 using unmodified carbon felt at different negative cathode potentials viz. −0.8, −1.0 and −1.2 V vs Ag/AgCl. Propionic acid was produced as secondary main product after acetic acid. The applied voltage of −1.2 V reported the highest amount of acetic acid with production rates of 949 mg L−1 d−1 (15.81 mM d−1). The increased cathode potential from −0.8 to − 1.2 V enhanced the maximum acetic acid production. The maximum acetic acid production achieved at a voltage of −1.2 V was 1.72 and 1.17 folds higher than MES operation at −0.8 and −1.0 V, respectively. Highest amount of propionic acid with the production rates of 322 mg L−1 d−1 (4.34 mM d−1) was obtained at −1.0 V, which was 1.20 and 2.12 times higher than the MES operation at −0.8 and −1.2 V, respectively. Scanning electron microscopy revealed dense biofilm and strong attachment of diverse microorganisms on the biocathode.

Probiotic microorganisms – Propionibacterium ssp

Propionic acid bacteria belong to probiotic microorganisms, probiotic properties of which have not yet been thoroughly investigated. The research describes the probiotic features of milk propionic acid bacteria, including growth at high acidity, tolerance to bile acid, ability to suppress pathogenic microorganisms, and antibiotic susceptibility, as well as the ability to extend the shelf life of various fermented milk products due to the synthesis of propionic acid. Propionic acid bacteria have a robust nature, which makes it easy to overcome technological difficulties in the process of optimizing production. This enables them to be used in the future for the production of various fermented probiotic foods.

Effects of Mulberry Branch and Leaves Silage on Microbial Community, Rumen Fermentation Characteristics, and Milk Yield in Lactating Dairy Cows

This study investigated the effects of mulberry branch and leaves (MBL) silage on milk yield, ruminal fermentation, and bacteria composition in dairy cows. Thirty-six mid-lactation cows were selected and randomly allocated into three groups. The control group (C) was fed on a total mixed ratio (TMR) diet, while the experimental groups were fed on TMR supplemented with 5% (L) and 10% (H) MBL silage. The experiment lasted for eight weeks, including two weeks of adaption. The results showed that Group H had an increased milk yield, milk fat content (p < 0.05), and 4% feed conversion ratio (p = 0.10). In addition, rumen propionic acid was significantly increased (p < 0.05), while acetate/propionate was significantly decreased (p < 0.05) in the high MBL silage group. The microbiome analysis showed that Bacteroides, Firmicutes, and Proteobacteria were the predominant phyla. Compared with Group C, the abundance of Bacteroides was significantly decreased (p < 0.01), while the Firmicutes and Proteobacteria were increased but not significantly different in Groups L and H. Prevotella was significantly decreased (p < 0.05) in the MBL silage groups, and Succinivibrionaceae_UCG-001 was increased in Group H. The correlation analysis showed that eight bacterial species belonging to Firmicutes were positively correlated with propionic acid. However, four bacterial species belonging to the Bacteroides group were negatively correlated with propionic acid. In conclusion, feed supplementation with about 5–10% of MBL silage could modulate the rumen microbiota and fermentation, and increase the abundance of fiber-digesting, propionic acid synthesis and milk fat-related microorganisms, thus improving milk yield in dairy cows.

Metabolic profiling analysis of the vitamin B12 producer Propionibacterium freudenreichii.

Vitamin B12 (VB12) is an indispensable cofactor of metabolic enzymes and has been widely used in the food and pharmaceutical industries. In this study, the effects of medium composition on VB12 production by Propionibacterium freudenreichii were evaluated and optimized based on statistical experiments. The results showed that glucose, yeast extract, KH2PO4, and glycine have significant effects on VB12 production. The final titer of VB12 reached 8.32 ± 0.02 mg/L, representing a 120% increase over the non‐optimized culture medium. We employed a metabolomics approach to analyze the differences of metabolite concentrations in P. freudenreichii cells cultivated in the original medium and optimized fermentation medium. Using multivariate data analysis, we identified a range of correlated metabolites, illustrating how metabolomics can be used to explain VB12 production changes by corresponding differences in the overall cellular metabolism. The concentrations of many metabolic intermediates of glycolysis, the Wood–Werkman cycle, the TCA cycle, and amino acid metabolism were increased, which contributed to the synthesis of propionic acid and VB12 due to an improved supply of energy and precursors.

Metabolic Flux Analysis of Simultaneous Production of Vitamin B12 and Propionic Acid in a Coupled Fermentation Process by Propionibacterium freudenreichii.

The metabolic processes involved in simultaneous production of vitamin B12 and propionic acid by Propionibacterium freudenreichii are very complicated. To further investigate the regulatory mechanism of this metabolism, a simplified metabolic network was established. The effects of glucose feeding, propionic acid removal, and 5,6-dimethylbenzimidazole (DMB) addition on the metabolic flux distribution were investigated. The results showed that synthesis of propionic acid can be increased by increasing the metabolic flux through the oxaloacetate and methylmalonyl-CoA branches in the early and middle stages of the coupled fermentation. After DMB addition, the synthesis of vitamin B12 was significantly enhanced via increased metabolic flux through the δ-aminolevulinate branch, which promoted the synthesis of uroporphyrinogen III, a precursor of vitamin B12. Therefore, the analysis of metabolic flux at key nodes can provide theoretical guidance for the optimization of P. freudenreichii fermentation processes. In an experimental coupled fermentation process, the concentrations of vitamin B12 and propionic acid reached 21.6 and 50.12 g/L respectively, increased by 105.71% and 73.91% compared with batch fermentation, which provides a new strategy for industrial production.

Increasing Biogas Yield from Fodder by Microbial Stimulation of Propionic Acid Synthesis in Grass Silages

A new direction in the use of lactic acid bacteria inoculants is their application for renewable raw materials ensiling for biogas production. The aim of the study was to demonstrate the possibility of stimulating the synthesis of propionic acid in the process of co-fermentation of selected strains of Lactobacillus buchneri and L. diolivorans as well as L. buchneri and Pediococcus acidilactici. L. buchneri KKP 2047p and P. acidilactici KKP 2065p were characterized by the special capabilities for both synthesis and metabolism of 1,2-propanediol. L. diolivorans KKP 2057p stands out for the ability to metabolize 1,2-propanediol to propionic acid. As a result of the co-fermentation a concentration of propionic acid was obtained at least 1.5 times higher in the final stage of culture in comparison to cultivating individual species of bacteria separately. The results of in vitro experiments were applied in agricultural practice, by application of two lactic acid bacteria inoculants in ensiling of grass silage and improving its suitability for biogas production. Grass silages made with the addition of the inoculant were characterized by the content of 1,2-propanediol, 1-propanol and propionic acid ensured extension of the aerobic stability from 4 to 7 days in comparison to untreated silages. It was found that the use of both inoculants resulted in an approximately 10–30% increase in biogas yield from this raw material.

Transcriptomics and Proteomics Analyses of the Responses of Propionibacterium acidipropionici to Metabolic and Evolutionary Manipulation.

We first performed a combination of metabolic engineering (deletion of ldh and poxB and overexpression of mmc) with evolutionary engineering (selection under oxygen stress, acid stress and osmotic stress) in Propionibacterium acidipropionici. The results indicated that the mutants had superior physiological activity, especially the mutant III obtained from P. acidipropionici-Δldh-ΔpoxB+mmc by evolutionary engineering, with 1.5–3.5 times higher growth rates, as well as a 37.1% increase of propionic acid (PA) titer and a 37.8% increase PA productivity compared to the wild type. Moreover, the integrative transcriptomics and proteomics analyses revealed that the differentially expressed genes (DEGs) and proteins (DEPs) in the mutant III were involved in energy metabolism, including the glycolysis pathway and tricarboxylic acid cycle (TCA cycle). These genes were up-regulated to supply increased amounts of energy and precursors for PA synthesis compared to the wild type. In addition, the down-regulation of fatty acid biosynthesis and fatty acid metabolism may indicate that the repressed metabolic flux was related to the production of PA. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was performed to verify the differential expression levels of 16 selected key genes. The results offer deep insights into the mechanism of high PA production, which provides the theoretical foundation for the construction of advanced microbial cell factories.

Metabolic perturbation of acrylate pathway in Lactobacillus plantarum

Engineering microbes with heterologous pathway for production of bio-based products has received considerable attention. Reconstituting such non-native pathway in addition to desired product formation often brings an allosteric modulation in enzymes competing at fragile nodes that result in by-product redistribution, in order to retain energy and redox balance. This work, Lactobacillus plantarum engineered with acrylate pathway for propionate production was studied under similar perspectives. Upon expression, the heterologous pathway did not result in propionic acid production under standard glucose concentration of 20 g/L, but 0.01 mM of propionate was formed when grown under low glucose concentration of 1 g/L. Further analysis of secreted metabolites with increased glucose concentration of 10 and 30 g/L remained futile towards propionate formation but showed reorientation in pyruvate metabolism which was related to the control imposed by the host to regulate the hidden constraints caused by gene perturbation. Further, it was ensured that the limitation of supplements did not play any functional role in inhibiting propionic acid synthesis but still followed similar metabolic pattern which was quite unclear though interpreted to certain extent. Thus, the findings gave insights into physiological and metabolic capabilities of Lactobacillus plantarum that at least in principle can be used to enhance the strain performance for increased propionic acid production.

Evaluation of the ability to metabolize 1,2-propanediol by heterofermentative bacteria of the genus Lactobacillus

Background. New directions of research on lactic acid bacteria include investigation of metabolic pathways for the synthesis and/or metabolism of 1,2-propanediol, commonly used in the food and chemical industry, medicine, pharmacy and cosmetology as well as agriculture. The objective of this study was to compare the capacity of strains representing three diverse heterofermentative species belonging to the genus Lactobacillus to synthesize and/or transform 1,2-PD as well as to suggest new directions of research aimed at commercial use of this metabolite. Results. The novel strain of Lactobacillus buchneri A KKP 2047p, characterized as exhibiting an unusual trait for that species in the form of capacity to metabolize 1,2-PD, grew poorly in a medium containing 1,2-PD as a sole carbon source. The supplementation with glucose facilitated rapid growth of bacteria and use of 1,2-PD for the synthesis of propionic acid. A similar observation was noted for Lactobacillus reuteri . On the other hand, Lactobacillus diolivorans effectively metabolized 1,2-PD which was the sole carbon source in the medium, and the addition of glucose inhibited the synthesis of propionic acid. The experiments also investigated the effect of cobalamin as a diol dehydratase coenzyme involved in the propionic acid synthesis from 1,2-PD whose addition promoted the yield of the reaction in the case of all tested strains. Conclusions: All tested isolates showed the ability to effectively metabolize 1,2-PD (in the presence of cobalamin) and its conversion to propionic acid, which reveals that investigated bacteria meet the essential requirements of microorganisms with a potential application. Normal 0 false false false PL X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Times New Roman; mso-bidi-theme-font:minor-bidi; mso-ansi-language:PL;}

Chemoselective synthesis of propionic acid from biomass and lactic acid over a cobalt catalyst in aqueous media

A new non-fermentative process for the transformation of biomass carbohydrates and lactic acid (LA) into propionic acid (PA) was first reported over a cobalt catalyst in water.

Production of propionic acid via hydrodeoxygenation of lactic acid over FexOy catalysts

Efficient synthesis of propionic acid from lactic acid using FeyOx catalyst via hydrodeoxygenation has been achieved.

Hydrogen production using an anaerobic baffled reactor – Mass balances for pathway analysis and gas composition profiles

This study investigated pathways for anaerobic hydrogen production from biomass at low pH values, also known as dark fermentation. A 200 l bench scale anaerobic baffled reactor with four internal compartments was used for hydrogen production from wheat starch. The liquid fermentation products and hydrodynamic characteristics were analyzed using high performance liquid chromatography, tracer studies, and gas analysis. A mean residence time of 29 h and a feed strength of 4 gCOD/l resulted in a total gas production of 230 l/d containing 42% hydrogen and 11% methane. The gas collected from the different compartments highly differed in composition showing a partial phase separation, with maximum H2 concentrations of up to 60% observed in the first compartment. 49% and 44% of the total H2 produced were derived during the formation of acetic and butyric acid respectively. Just 8% of the H2 was produced during propionic acid synthesis. Concentrations up to 1 g/l lactic acid built by the bifidum pathway was also observed.

Synthesis of propionic acid at a gold electrode by electrochemical technique

In recent years, catalytic properties of gold have played a major role in the chemistry of environmentally safe substances. In this study, propionic acid was synthesized using electrochemical oxidation on a gold plate electrode in potassium hydroxide. Five hours of electrochemical reaction at a constant voltage was carried out using the chronocuolom- etry method. Propionaldehyde was oxidized electrochemically to propionic acid as verified by the characterization data from high performance liquid chromatography and Fourier transform infrared spectroscopy. The proposed mechanism of the reaction showed the importance of the OH - species in the synthesis reaction.

Improved production of propionic acid in Propionibacterium jensenii via combinational overexpression of glycerol dehydrogenase and malate dehydrogenase from Klebsiella pneumoniae.

Microbial production of propionic acid (PA), an important chemical building block used as a preservative and chemical intermediate, has gained increasing attention for its environmental friendliness over traditional petrochemical processes. In previous studies, we constructed a shuttle vector as a useful tool for engineering Propionibacterium jensenii, a potential candidate for efficient PA synthesis. In this study, we identified the key metabolites for PA synthesis in P. jensenii by examining the influence of metabolic intermediate addition on PA synthesis with glycerol as a carbon source under anaerobic conditions. We also further improved PA production via the overexpression of the identified corresponding enzymes, namely, glycerol dehydrogenase (GDH), malate dehydrogenase (MDH), and fumarate hydratase (FUM). Compared to those in wild-type P. jensenii, the activities of these enzymes in the engineered strains were 2.91- ± 0.17- to 8.12- ± 0.37-fold higher. The transcription levels of the corresponding enzymes in the engineered strains were 2.85- ± 0.19- to 8.07- ± 0.63-fold higher than those in the wild type. The coexpression of GDH and MDH increased the PA titer from 26.95 ± 1.21 g/liter in wild-type P. jensenii to 39.43 ± 1.90 g/liter in the engineered strains. This study identified the key metabolic nodes limiting PA overproduction in P. jensenii and further improved PA titers via the coexpression of GDH and MDH, making the engineered P. jensenii strain a potential industrial producer of PA.

Comparative metabolomics analysis of the key metabolic nodes in propionic acid synthesis in Propionibacterium acidipropionici

Propionic acid (PA) is an important platform chemical used in the agriculture, food, and pharmaceutical industries. The biosynthesis of PA by propionibacteria has become an attractive alternative to traditional petrochemical processes owing to the environmentally friendly features of biorefinery. In a previous study, we significantly increased PA production in Propionibacterium acidipropionici by improving acid tolerance via genome shuffling. In this study, we undertook metabolomics analysis of parental P. acidipropionici and its genome-shuffled mutant to find the key metabolic nodes influencing PA production. In total, 142 intracellular metabolites were identified, of which those produced in amounts of greater than twofold difference between the two strains were further investigated with principal components analysis. The regulatory functions of key metabolites involved in the PA biosynthetic pathway were also forecast and analyzed according to their potential impact on metabolism. The results indicated that the amounts of metabolic intermediates of glycolysis, the Wood–Werkman cycle, and amino acid metabolism differed markedly between parental P. acidipropionici and its mutants. Based on the results of comparative metabolomics analysis, exogenous addition of key metabolites (precursors and amino acids) was performed to improve PA production. Under optimized conditions, 105 mM lactate, 20 mM fumarate, and 30 mM succinate were added to the culture of P. acidipropionici CGMCC 1.2230 in a 3-L anaerobic fermenter, and the PA titer increased from 23.1 ± 12 to 35.8 ± 1.0 g/L. This study revealed the key metabolic nodes of PA synthesis in P. acidipropionici through comparative metabolomics analysis, which may be helpful for the metabolic engineering of P. acidipropionici for improved PA production.

The physiological state of Lactoccocus lactis and Propionibacterium freudenreichii strains in co-cultures induced by low temperature and osmotic stress

The bacterial physiological state, type of interactions and changes in metabolism ofLactococcus lactis and Propionibacterium freudenreichii strains in co-culture were studied in skimmed milk in response to osmotic [3% (w/v) NaCl] and low temperature (10°C) stress during long-term incubation. Changes in the integrity of cell membrane were examined by LIVE/DEAD® BacLight™ staining, and culture viability and bacterial interactions studies were performed with the use of the plate count technique. The profiles of volatile organic compounds were assessed by static headspace-gas chromatography. During the stationary growth phase, the number of LIVE cells with intact membranes was reduced in the presence of NaCl in comparison with control conditions, and a longer adaptation phase was observed at 10°C. The viability of starter cultures was high at ~108to 109 CFU/ml at the end of the experiment in all tested conditions. Our results point to the possibility of commensalisms interactions between lactic acid and propionic acid bacteria. Prolonged culture incubation contributed to the accumulation of acetoin, and it enhanced acetic acid and propionic acid synthesis during the stationary growth phase of propionic acid bacteria. Key words: Lactococcus lactis, Propionibacterium freudenreichii, viability, volatiles compounds, osmotic stress, low temperature stress.