Crude Glycerol Research Articles

Systems Metabolic Engineering of Clostridium tyrobutyricum for 1,3-Propanediol Production From Crude Glycerol.

Clostridium tyrobutyricum has emerged as a non-pathogenic microbial cell factory capable of anaerobic production of various value-added products, such as butyrate, butanol, and butyl butyrate. This study reports the first systematic engineering of C. tyrobutyricum for the heterologous production of 1,3-propanediol (1,3-PDO) from industrial by-product crude glycerol. Initially, the glycerol reductive pathway for 1,3-PDO production was constructed, and the unique glycerol oxidation pathway in C. tyrobutyricum was elucidated. Subsequently, the glycerol metabolism and 1,3-PDO synthesis pathways were enhanced. Furthermore, the intracellular reducing power supply and the fermentation process were optimized to improve 1,3-PDO production. Consequently, 54.06 g/L 1,3-PDO with a yield of 0.64 mol/mol and a productivity of 1.13 g/L·h was obtained using crude glycerol and fish meal. The strategies described herein could facilitate the engineering of C. tyrobutyricum as a robust host for synthesizing valuable chemicals.

Modelling the long-term dynamics and inhibitory effects of crude glycerol impurities in a methanogenic and sulfidogenic UASB bioreactor.

Modelling the long-term dynamics and inhibitory effects of crude glycerol impurities in a methanogenic and sulfidogenic UASB bioreactor.

Engineered yeast Yarrowia lipolytica as a chassis for biosynthesis of fatty acids from mannitol and macroalgal biomass extracts

BackgroundYarrowia lipolytica possesses the capability to utilize many unconventional carbon sources, such as crude glycerol, alkanes and fatty acids. Despite producing polyols, such as erythritol, arabitol and mannitol, the re-utilization of mannitol is not as efficient as erythritol utilization. Genes involved in mannitol uptake and metabolism in Y. lipolytica remain undescribed. However, deletion of the EYD1 gene (YALI0F01650g), believed to encode erythritol dehydrogenase, has been found to result in a high rate of growth on media containing mannitol as the sole carbon source. Therefore this unique feature was used for further fermentation studies on media containing macroalgal mannitol extracts, obtained from the brown alga Fucus vesiculosus, to produce value-added products.ResultsThe obtained strain AJD Δeyd1Dga1 was able to uptake pure and algal mannitol efficiently and produce high amounts of lipids, thanks to overexpression of the DGA1 gene (YALI0E32769g), encoding diacylglycerol (DAG) acyltransferase. The lipid content reached almost 32% of the overall dry biomass as compared to the wild type strain, where this value was more than 4 times lower. Additionally, the biomass at the end of the experiment was the highest among all of the tested strains, reaching 12.67 g/L, more than 50% higher than the control strain.ConclusionsThe results of this study shed new light on the potential for the yeast Y. lipolytica to utilize macroalgae biomass as a carbon source for production of value-added products, including biomass and lipids. Moreover, the increased mannitol utilization capabilities can provide new insight into mannitol metabolism, including its uptake, which is especially crucial, as the metabolic pathways for all polyols produced by this organism seem to be closely intertwined.

Catalytic Hydrothermal Liquefaction of Grape Pomace Using Ni-ZrO2-MSS and Ni-HZSM5 in a Water-Crude Glycerol Cosolvent.

This study focused on the catalytic hydrothermal liquefaction (HTL) of grape pomace using Ni-HZSM5 and Ni-ZrO2-modified steel slag (MSS) catalysts, employing a water-crude glycerol cosolvent. The research aimed to understand how temperature, solvent ratios, and crude glycerol composition affect biocrude yield and properties, and to evaluate the stability of regenerated catalysts. The results revealed that when fatty acids/glycerides-rich crude glycerol was used, the highest biocrude yield of 76 wt %, HHV of 41 MJ/kg, H/C ratio of 1.81, and energy recovery of 90.9% was achieved at 320 °C with 75% crude glycerol concentration in the cosolvent. Catalytic HTL with Ni-HZSM5 significantly reduced the acid content of the biocrude by 44%. Although Ni-ZrO2-MSS increased the biocrude yield from 44.07 to 49.97 wt %, it promoted the production of acids and reduced the esters in biocrude. TGA refinery cut results showed that both catalysts enhance diesel production, with Ni-HZSM5 yielding the highest diesel fraction (41.24%) compared to Ni-ZrO2-MSS (37.51%) and the noncatalytic process (33.56%). Moreover, both catalysts significantly reduced the production of heavier fractions, such as residual fuel oil and bitumen. While the modification significantly enhanced the BET surface area of raw steel slag from 4.04 to 49.61 m2/g in Ni-ZrO2-MSS, the surface area of the regenerated catalyst after HTL dropped to 15.88 m2/g, aligning with decreased H2 uptake, indicating a loss of active sites. Similarly, the surface area of Ni-HZSM5 decreased from 522.25 to 387.37 m2/g after HTL, while the pore volume increased from 0.2095 to 0.3425 cm3/g. However, the spent Ni-HZSM5 catalyst displayed an increase in H2 uptake (269.49 μmol/g) with a shift in the reduction peaks to higher temperatures, suggesting the creation of new active sites or changes in the dispersion of NiO species during the reaction. The TPO graphs confirm the presence of coke with an intermediate structure between amorphous and graphitic carbon.

Metabolic engineering of Pseudomonas chlororaphis P3 for high-level and directed production of phenazine-1,6-dicarboxylic acid from crude glycerol.

Metabolic engineering of Pseudomonas chlororaphis P3 for high-level and directed production of phenazine-1,6-dicarboxylic acid from crude glycerol.

Progress in the conversion of biodiesel-derived crude glycerol into biofuels and other bioproducts

Progress in the conversion of biodiesel-derived crude glycerol into biofuels and other bioproducts

Use of Wastewaters from Ethanol Distilleries and Raw Glycerol for Microbial Oil Production

The production of biodiesel from single-cell oils (SCOs) utilizing industrial wastes as feedstock presents an economically viable approach. To date, studies have rarely reported the utilization of vinasse combined with industrial glycerol for the production of SCO. This study aimed to assess the performance of a Rhodotorula toruloides strain in vinasse from ethanol distilleries supplemented with pure/raw glycerol as an affordable carbon feedstock for SCO production. Several critical factors, including the C/N ratio, the impact of impurities in the crude glycerol, the proper nitrogen source, and the effects of the vinasse compositions, were evaluated. The results showed that the incorporation of urea and raw glycerol increased the lipid content to 51.8 ± 1.6% and the lipid productivity to 0.034 ± 0.001 g L−1h−1. Elevated biomass (42.5 g L−1) and lipid (11.0 g L−1) concentrations indicated that impurities in the raw glycerol positively affected the growth and lipid accumulation of this strain. Notably, supplementing raw glycerol to the vinasse led to a 16.1% increase in biomass concentration and a 25.7% rise in lipid content, significantly enhancing lipid productivity by 59.6%. The fatty acid profile predominantly featured unsaturated fatty acids (96.8%), including high percentages of stearic acid (41.8 ± 2.6%), palmitic acid (21.8 ± 1.5%), and oleic acid (18.3 ± 1.4%), aligning with the standards for vegetable-oil-based biodiesel manufacture. Fed-batch strategies using pulse-feeding turned out to be less effective than the constant-flow feeding strategy with vinasse supplemented with raw glycerol, which achieved a higher lipid productivity of 0.30 g L−1h−1.

Changes in a glycerol-degrading bacterial community in an upflow anaerobic reactor for 1,3-propanediol production

The evolution of the bacterial community in an up-flow anaerobic reactor with silicone support, continuously fed with pure glycerol (day 0–293) and crude glycerol (day 294–362), was studied. Biomass from a former glycerol-degrading reactor was used as inoculum. The maximum yield and productivity of 1,3-propanediol (PDO) (0.62 mol.mol-gly−1 and 14.7 g.L−1.d−1, respectively) were obtained with crude glycerol. The inoculum had low diversity, with dominance of Lactobacillus (70.6%) and Klebsiella/Raoultella (23.3%). After 293 days of feeding with pure glycerol, the abundance of both taxa decreased to less than 10%, either in the attached biofilm or in the biomass growing in suspension. The genus Clostridium and members of the Ruminococcaceae family then became the majority. In the period after feeding with crude glycerol, Clostridium remained as the majority genus in the biofilm; however, it was partially replaced in the suspension by Eubacterium, a non-glycerol degrading bacterium. This fact, together with the prevalence of other glycerol-degrading genera in the biofilm, such as Caproiciproducens and Lactobacillus, indicated that the bacteria attached to the silicone support were responsible for converting glycerol into 1,3-PDO. Therefore, to increase the 1,3-PDO productivity, a good approach would be to maximize the amount of reactor support. Other genera that do not degrade glycerol, such as Anaerobacter and Acetomaculum, thrived at the expense of cellular decay material. The Canonical Correspondence Analysis demonstrated that the origin of glycerol is an important variable to consider during the bioreactor operation for producing 1,3-PDO, while the glycerol loading rate is not.Graphical abstractKey points• Microbial community showed robustness in a range of operational conditions.• A significantly high 1,3-propanediol yield can be achieved using crude glycerol.• The attached biofilm appears to be key to the high production of 1,3-propanediol.

Crude glycerol as a sustainable source for carbon-based photoluminescent material

Crude glycerol as a sustainable source for carbon-based photoluminescent material

Expression of Concern: "Gram-scale synthesis of ZnS/NiO core-shell hierarchical nanostructures and their enhanced H2 production in crude glycerol and sulphide wastewater" [Environ. Res., 199 (2021) 111323

Expression of Concern: "Gram-scale synthesis of ZnS/NiO core-shell hierarchical nanostructures and their enhanced H2 production in crude glycerol and sulphide wastewater" [Environ. Res., 199 (2021) 111323

Model-based study of Yarrowia lipolytica cultivation on crude glycerol under different fermentation modes: Development of a membrane bioreactor process.

Model-based study of Yarrowia lipolytica cultivation on crude glycerol under different fermentation modes: Development of a membrane bioreactor process.

Synergistic effects of Tween 20 and ethephon on yeast oil and β-carotene co-production by Rhodosporidium toruloides using purified biodiesel-derived crude glycerol as an alternative carbon source.

Synergistic effects of Tween 20 and ethephon on yeast oil and β-carotene co-production by Rhodosporidium toruloides using purified biodiesel-derived crude glycerol as an alternative carbon source.

Non-sterile fermentation for enhanced lipid production by Cutaneotrichosporon oleaginosum using bifunctional benzamide as selective antibacterial agent and unique nitrogen source

Non-sterile fermentation for enhanced lipid production by Cutaneotrichosporon oleaginosum using bifunctional benzamide as selective antibacterial agent and unique nitrogen source

Multienzymatic Platform for Coupling a CCU Strategy to Waste Valorization: CO2 from the Iron and Steel Industry and Crude Glycerol from Biodiesel Production.

Ongoing climate crisis demands the development of carbon capture and utilization (CCU) technologies that emphasize simplicity, eco-sustainability, and cost-effectiveness. Enzymatic CO2 reduction emerges as an alternative to biotransforming this cheap raw material into high-value products under milder conditions. This work proposes a multienzymatic platform to reduce CO2 to formate by formate dehydrogenase (FDH) and oxidize glycerol to dihydroxyacetone (DHA) by glycerol dehydrogenase (GlyDH), allowing for efficient cofactor regeneration. Through studies such as pH operating range, enzyme stability, FDH/GlyDH ratio, and reaction medium engineering to achieve optimal soluble CO2 concentrations, the reaction with a gas mixture of 24% CO2 yielded 5.7 mM formate and 6 mM DHA after 30 h, achieving a 92.3% CO2 conversion. To evaluate the feasibility under industrially relevant conditions, a synthetic gas mixture mimicking the composition of the iron and steel industry off-gases (24.5% CO2) and crude glycerol (64% v/v) from biodiesel production was tested as substrates. The simultaneous production was successful, yielding 3.1 mM formate and 4.4 mM DHA. Formic acid was subsequently purified using liquid-liquid extraction, employing the green solvent 2-methyltetrahydrofuran (2-MTHF). For the first time to our knowledge, a CCU strategy has been successfully coupled with industrial waste valorization, obtaining two high-value molecules by means of a robust, profitable, and easily manageable multienzymatic system.

High-Yield Production of Polyhydroxybutyrate and Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from Crude Glycerol by a Newly Isolated Burkholderia Species Oh_219.

Crude glycerol (CG), a major biodiesel production by-product, is the focus of ongoing research to convert it into polyhydroxyalkanoate (PHA). However, few bacterial strains are capable of efficiently achieving this conversion. Here, 10 PHA-producing strains were isolated from various media. Among them, Burkholderia sp. Oh_219 exhibited the highest polyhydroxybutyrate (PHB) production from glycerol and was therefore characterized further. Burkholderia sp. Oh_219 demonstrated significant tolerance to major growth inhibitors in CG and metabolized the fatty acids present as impurities in CG. Furthermore, the Oh_219 strain was genetically engineered using phaCBP-M-CPF4 and phaJPa to enable the fatty acid-based production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), a component of CG. The resulting strain produced PHBHHx containing 1.0-1.3 mol% of 3HHx from CG. Further supplementation with capric and lauric acids increased the 3HHx molar fraction to 9.7% and 18%, respectively. In a 5 L fermenter, the Oh_219 strain produced 15.3 g/L PHB from 29.6 g/L biomass using a two-stage fermentation system. This is the highest yield reported for PHA production from glycerol by Burkholderia spp. Additionally, PHB produced from CG had a lower melting point than that from pure glycerol and fructose. Taken together, Burkholderia sp. Oh_219 is a promising new candidate strain for producing PHA from CG.

Comparative study of conventional and process intensification by reactive distillation designs for glycerol carbonate production from glycerol and diethyl carbonate

Glycerol carbonate (GC) can be produced from glycerol (GL), a low-value byproduct in the biodiesel industry. In this work, continuous processes of GC production via transesterification from crude GL and diethyl carbonate (DEC) were developed using Aspen Plus. Two cases were considered, and their process performances were compared. In Case I, a conventional design consisted of a continuously stirred tank reactor for the reaction section and a distillation column for the purification section. In Case II, a process intensification design consisted of a reactive distillation column that could accommodate both reaction and purification within a single column. In both cases, the process optimizations were carried out by connecting the process models in Aspen Plus to MATLAB, using the Genetic Algorithm as the optimizer. The results showed that Case II was superior to Case I in terms of energy utilization, CO2 emissions, and economics with the specific energy consumption of 1.92 kWh/kg of diethyl carbonate, % internal rate of return of 274, payback period of 1.44 years, and CO2 emissions of 0.26 kg CO2/kg DEC. Lastly, the proposed process in Case II was compared with the GC production using dimethyl carbonate (DMC). It was found that using DEC was superior to DMC due to easier separation and glycidol avoidance.

Enhancement of wheat straw pellet quality for bioenergy through additive blending

ABSTRACT Densification of biomass through pelletizing offers a promising approach to producing clean biofuels from renewable resources. This study, which investigates the impact of additive blends on wheat straw pellet making and upgrading the physiochemical properties, has revealed exciting possibilities. Five additives, including sawdust (SD), bentonite clay (BC), corn starch (S), crude glycerol (CG), and biochar (BioC), were chosen for this study. Pellets were made from seven different combinations using a laboratory-scale pellet mill. The resulting pellets’ physical and elemental properties were assessed against ISO 17,225-8 standards. Compared to control pellets, additive blends (T3-T7) exhibited significant improvements in mechanical durability (80% to 99%), tensile strength (0.36 MPa to 2.09 MPa), and bulk density (244 kg/m3 to 665.21 kg/m3), all meeting ISO standards. AdditionaUF000llylly, these blends maintained low fines content (<2%) and water absorption capacity (<2%, except T1 and T5). Furthermore, fixed carbon content increased from 11.1% to 30.90%, and energy content rose from 17.02 MJ/kg to 20.36 MJ/kg, which showed a significant synergistic effect of blending additives. These findings underscore the potential of wheat straw as a viable biomass source for bioenergy production through pelletization, offering a hopeful outlook for the future of renewable energy. However, further research is necessary to optimize additive mixing ratios for even greater pellet quality. Implications: The study successfully demonstrated that addingspecific materials during wheat straw pelletizing significantly improves thequality of the pellets as a biofuel. Here are the key implications of the statement. Wheat straw is a promising biofuel source: Densification through pelletizing makes wheat straw a viable option for renewable energy production. Additives enhance pellet quality: Sawdust, bentonite clay, corn starch, crude glycerol, and biochar improve the pellets’ durability, strength, density, and energy content. Improved pellet properties meet industry standards: The resulting pellets meet ISO standards for mechanical strength, bulk density, and fines content. Synergistic effect of blending: Combining different additives leads to a greater improvement than using them individually. Need for further research: Optimizing the ratios of these additives can potentially create even better biofuel pellets. Overall, the study highlights the potential ofwheat straw pelletizing with specific additives as a sustainable and efficientbiofuel option. There’s room for further improvement, but the initial findingsare promising.

Techno-economic assessment of biodiesel-derived crude glycerol purification processes

This study presents a comprehensive techno-economic assessment of three glycerol purification processes: Membrane Separation (MBP), Vacuum Distillation (VDP), and Ion Exchange Purification (IEP). The analysis evaluated these processes based on...

Examination of Xanthan Production on Biodiesel Industry Effluent-based Medium in Lab-scale Bioreactor

Xanthan is microbial polysaccharide with outstanding rheological properties, non-toxic nature, biodegradability, and biocompatibility. This biopolymer is widely used in food, biomedical, pharmaceutical, petrochemical, chemical and textile industry. Industrial xanthan production is generally conducted by aerobic submerged cultivation of Xanthomonas campestris strains on the media with glucose or sucrose under optimal conditions. Results from previous research indicate that xanthan can be successfully produced on media containing crude glycerol from biodiesel industry by different Xanthomonas species. The aim of this study was to examine the course of xanthan biosynthesis by the reference strain X. campestris ATCC 13951 in lab-scale bioreactor on medium containing crude glycerol generated in domestic biodiesel factory. The bioprocess was monitored by the analysis of cultivation medium samples taken in predetermined time intervals, and its success was estimated based on the xanthan concentration in the medium, separated biopolymer average molecular weight and degree of nutrients conversion. At the end of bioprocess, cultivation medium contained 12.34 g/L of xanthan with the average molecular weight of 3.04∙105 g/mol. Within this study, the achieved degree of glycerol, total nitrogen and total phosphorous conversion were 75.91%, 53.27% and 38.96%, respectively.

Sustainable production of a highly pure (R,R)-2,3-butanediol from crude glycerol using metabolically engineered Klebsiella pneumoniae GEM167 strain

BackgroundAmong 2,3-butanediol (2,3-BDO) stereoisomers, (R,R)-2,3-BDO is particularly noteworthy for its application in the agricultural industry. It is an eco-friendly plant immune system stimulant, promoting plant growth and enhancing resistance to biotic and abiotic stresses.ResultsThis study aimed to address the limitations of a previous study, which produced (R,R)-2,3-BDO with only 98% purity despite Kp-dhaD overexpression. First, BLi-gldA demonstrated significantly higher activity and selectivity in converting racemic acetoin to (R,R)-2,3-BDO compared to others among 2,3-BDO dehydrogenases (Kp-dhaD and Kp-gldA from Klebsiella pneumoniae, and BLi-gldA from Bacillus licheniformis). The K. pneumoniae GEM167 ΔadhEΔldhAΔbudC-BLi-gldA/pETM6 strain produced the highest (R,R)-2,3-BDO amount, with 99% purity (73.51 ± 1.69 g/L at 48 h), by isopropyl β-D-1-thiogalactopyranoside addition at the early exponential growth phase (6 h) compared to other cell growth phases. The availability of crude glycerol was investigated, and crude glycerol promoted cell growth resulting in efficient (R,R)-2,3-BDO in the early stage of culture [90.32 ± 1.12 g/L (R,R)-2,3-BDO with 99.0% purity after 60 h]. The productivity and yield remained comparable for crude glycerol (1.51 g/L/h, 0.41 g/g) and pure glycerol (1.53 g/L/h, 0.43 g/g).ConclusionsThis study successfully produced 99% enantiopure (R,R)-2,3-BDO from crude glycerol for the first time using the K. pneumoniae GEM167 ΔadhEΔldhAΔbudC-BLi-gldA/pETM6 strain. (R,R)-2,3-BDO production from crude glycerol, a biodiesel process byproduct, is expected to contribute to a sustainable and circular biomass supply chain and biodiesel production system by positively influencing the stable cultivation of biodiesel crops even under unpredictable climate conditions.Graphical abstract