| 1. |
- Abouhmad, Adel, et al.
(författare)
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Exploring the enzymatic and antibacterial activities of novel mycobacteriophage lysin b enzymes
- 2020
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 21:9
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Tidskriftsartikel (refereegranskat)abstract
- Mycobacteriophages possess different sets of lytic enzymes for disruption of the complex cell envelope of the mycobacteria host cells and release of the viral progeny. Lysin B (LysB) enzymes are mycolylarabinogalactan esterases that cleave the ester bond between the arabinogalactan and mycolic acids in the mycolylarabinogalactan-peptidoglycan (mAGP) complex in the cell envelope of mycobacteria. In the present study, four LysB enzymes were produced recombinantly and characterized with respect to their enzymatic and antibacterial activities. Examination of the kinetic parameters for the hydrolysis of para-nitrophenyl ester substrates, shows LysB-His6 enzymes to be active against a range of substrates (C4-C16), with a catalytic preference towards p-nitrophenyl laurate (C12). With p-nitrophenyl butyrate as substrate, LysB-His6 enzymes showed highest activity at 37◦C. LysB-His6 enzymes also hydrolyzed different Tween substrates with highest activity against Tween 20 and 80. Metal ions like Ca2+ and Mn2+ enhanced the enzymatic activity of LysB-His6 enzymes, while transition metal ions like Zn2+ and Cu2+ inhibited the enzymatic activity. The mycolylarabinogalactan esterase activity of LysB-His6 enzymes against mAGP complex was confirmed by LC-MS. LysB-His6 enzymes showed marginal antibacterial activity when tested alone against Mycobacterium smegmatis, however a synergetic activity was noticed when combined with outer membrane permealizers. These results confirm that LysB enzymes are lipolytic enzymes with potential application as antimycobacterials.
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| 2. |
- Abouhmad, Adel, et al.
(författare)
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Immobilization to Positively Charged Cellulose Nanocrystals Enhances the Antibacterial Activity and Stability of Hen Egg White and T4 Lysozyme
- 2017
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 18:5, s. 1600-1608
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Tidskriftsartikel (refereegranskat)abstract
- Antibacterial bionanostructures were produced from cellulose nanocrystals (CNC) with immobilized lysozyme from hen egg white (HEW) and T4 bacteriophage, respectively. The nanocrystals were prepared from microcrystalline cellulose by ammonium persulfate oxidation with a yield of 68% and having an average size of 250 nm and low polydispersity index. HEW lysozyme (HEWL) and T4 lysozyme (T4L) were immobilized to CNC by different mechanisms including adsorption and covalent coupling to carbodiimide-activated carboxylate groups and to glutaraldehyde-activated aminated CNC (Am-CNC), respectively. The effect of immobilization on the enzymatic activity (both lytic and hydrolytic) and antibacterial activity of the lysozymes was studied using different methods. Am-CNC-lysozyme conjugates retained the highest lytic activity, 86.3% and 78.3% for HEWL and T4L, respectively. They also showed enhanced bactericidal activity with high potency against Gram-positive as well as Gram-negative bacteria in a relatively shorter time as compared to the free enzymes and resulted in extensive cellular damage, as shown by transmission electron microscopy. The enhanced antibacterial activity was correlated with the increase in zeta potential of Am-CNC-lysozyme conjugates. The immobilized lysozyme preparations further exhibited enhanced storage stability at 4 and 22 °C.
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| 3. |
- Alkhalili, Rawana N., et al.
(författare)
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Antimicrobial protein candidates from the thermophilic Geobacillus sp. Strain ZGt-1 : Production, proteomics, and bioinformatics analysis
- 2016
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 17:8
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Tidskriftsartikel (refereegranskat)abstract
- A thermophilic bacterial strain, Geobacillus sp. ZGt-1, isolated from Zara hot spring in Jordan, was capable of inhibiting the growth of the thermophilic G. stearothermophilus and the mesophilic Bacillus subtilis and Salmonella typhimurium on a solid cultivation medium. Antibacterial activity was not observed when ZGt-1 was cultivated in a liquid medium; however, immobilization of the cells in agar beads that were subjected to sequential batch cultivation in the liquid medium at 60 °C showed increasing antibacterial activity up to 14 cycles. The antibacterial activity was lost on protease treatment of the culture supernatant. Concentration of the protein fraction by ammonium sulphate precipitation followed by denaturing polyacrylamide gel electrophoresis separation and analysis of the gel for antibacterial activity against G. stearothermophilus showed a distinct inhibition zone in 15-20 kDa range, suggesting that the active molecule(s) are resistant to denaturation by SDS. Mass spectrometric analysis of the protein bands around the active region resulted in identification of 22 proteins with molecular weight in the range of interest, three of which were new and are here proposed as potential antimicrobial protein candidates by in silico analysis of their amino acid sequences. Mass spectrometric analysis also indicated the presence of partial sequences of antimicrobial enzymes, amidase, and DD-carboxypeptidase.
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| 4. |
- Cavero-Olguin, Victor Hugo, et al.
(författare)
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Membrane-based continuous fermentation with cell recycling for propionic acid production from glycerol by Acidipropionibacterium acidipropionici
- 2023
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Background: Microbial production of propionic acid (PA) from renewable resources is limited by the slow growth of the producer bacteria and product-mediated inhibition. The present study evaluates high cell density continuous PA fermentation from glycerol (Gly) using Acidipropionibacterium acidipropionici DSM 4900 in a membrane-based cell recycling system. A ceramic tubular membrane filter of 0.22 μm pore size was used as the filtering device for cell recycling. The continuous fermentations were run sequentially at dilution rates of 0.05 and 0.025 1/h using varying glycerol concentrations and two different yeast extract concentrations.Results: PA volumetric productivity of 0.98 g/L.h with a product yield of 0.38 gPA/gGly was obtained with 51.40 g/L glycerol at a yeast extract concentration of 10 g/L. Increasing the glycerol and yeast extract concentrations to 64.50 g/L and 20 g/L, respectively, increased in PA productivity, product yield, and concentration to 1.82 g/L.h, 0.79 gPA/gGly, and 38.37 g/L, respectively. However, lowering the dilution rate to 0.025 1/h reduced the production efficiency. The cell density increased from 5.80 to 91.83 gCDW/L throughout the operation, which lasted for a period of 5 months. A tolerant variant of A. acidipropoinici exhibiting growth at a PA concentration of 20 g/L was isolated at the end of the experiment.Conclusions: Applying the current approach for PA fermentation can overcome several limitations for process industrialization.
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| 5. |
- Cavero-Olguin, Victor Hugo, et al.
(författare)
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Propionic acid production from glycerol in immobilized cell bioreactor using an acid-tolerant strain of Propionibacterium acidipropionici obtained by adaptive evolution
- 2021
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113. ; 110, s. 223-230
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Tidskriftsartikel (refereegranskat)abstract
- Propionic acid (PA) production from agro-industrial residues using propionibacteria has gained interest as an alternative to fossil-based process. Microbial production is however characterized by product inhibition, lowering the product titers and productivity. In this study, Propionibacterium acidipropionici DSMZ4900 was subjected to adaptive evolution to tolerate higher acid concentrations. The strain adapted to growth in medium spiked with 20 g/L PA exhibited improved product titer (16.8 vs 8.72 g/L) and productivity (0.52 vs 0.17 g/L·h) with glycerol as carbon source in batch fermentations. It was immobilized on polyethyleneimine coated recycled glass beads Poraver® and used for fermentations in recycle batch mode with increasing glycerol concentration and decreasing pH, respectively. Doubling yeast extract concentration raised PA yield and productivity by >1.5 fold. Glycerol at 100 g/L was completely consumed to give ∼58 g/L PA at yield of 0.64 mol/mol and productivity of 0.28 g/L·h at pH 6.5. Decreasing fermentation pH to 5.0 increased PA productivity to 0.23 g/L·h from 0.14 g/L·h at pH 6.0 with 20 g/L glycerol, while immobilized cells exhibited no growth. The study shows combination of adaptive evolution and immobilization of cells to result in a robust system for PA fermentation at high glycerol concentration and lower pH.
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| 6. |
- Dishisha, Tarek
(creator_code:cre_t)
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3-hydroxypropionaldehyde detection and extraction
- 2018
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- The present invention relates to a method of extg. 3-hydroxypropionaldehyde (3-HPA) and/or derivs. thereof from an aq. soln. comprising 3-HPA. This method comprises (a) contacting the aq. soln. comprising 3-HPA with chitosan and/or chitosan comprising polymers, (b) sepg. the 3-HPA bound chitosan and/or chitosan comprising polymers, and (c) washing the 3-HPA bound chitosan and/or chitosan comprising polymers at least once with a washing medium (wherein 3-HPA and/or derivs. thereof is in the washing medium).
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| 7. |
- Dishisha, Tarek, et al.
(författare)
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An economical biorefinery process for propionic acid production from glycerol and potato juice using high cell density fermentation.
- 2013
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 135, s. 504-512
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Tidskriftsartikel (refereegranskat)abstract
- An economically sustainable process was developed for propionic acid production by fermentation of glycerol using Propionibacterium acidipropionici and potato juice, a by-product of starch processing, as a nitrogen/vitamin source. The fermentation was done as high-cell-density sequential batches with cell recycle. Propionic acid production and glycerol consumption rates were dependent on initial biomass concentration, and reached a maximum of 1.42 and 2.30gL(-1)h(-1), respectively, from 50gL(-1) glycerol at initial cell density of 23.7g(CDW)L(-1). Halving the concentration of nitrogen/vitamin source resulted in reduction of acetic and succinic acids yields by ∼39% each. At glycerol concentrations of 85 and 120gL(-1), respectively, 43.8 and 50.8gL(-1) propionic acid were obtained at a rate of 0.88 and 0.29gL(-1)h(-1) and yield of 84 and 78mol%. Succinic acid was 13g% of propionic acid and could represent a potential co-product covering the cost of nitrogen/vitamin source.
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| 8. |
- Dishisha, Tarek, et al.
(författare)
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Batch- and continuous propionic acid production from glycerol using free and immobilized cells of Propionibacterium acidipropionici
- 2012
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 118C, s. 553-562
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Tidskriftsartikel (refereegranskat)abstract
- Propionicacid production from glycerol was studied using Propionibacterium acidipropionici DSM 4900 cells immobilized on polyethylenimine-treated Poraver (PEI-Poraver) and Luffa (PEI-Luffa), respectively. Using PEI-Luffa, the average productivity, yield and concentration of propionicacid from 40 g.L-1 glycerol were 0.29 g.L-1.h-1, 0.74 mol.mol-1 and 20.09 g.L-1, respectively, after four consecutive recycle-batches. PEI-Poraver supported attachment of 31 times higher amount of cells than PEI-Luffa and produced 20, 28 and 35 g.L-1propionicacid from 40, 65 and 85 g.L-1 glycerol, respectively (0.61 molPA.molGly-1). The corresponding production rates were 0.86, 0.43 and 0.35 g.L-1.h-1, which are the highest reported from glycerol via batch or fed-batch fermentations for equivalent propionicacid concentrations. Using a continuous mode of operation at a dilution rate of 0.1 h-1, cell washout was observed in the bioreactor with free cells; however, propionicacid productivity, yield and concentration were 1.4 g.L-1.h-1, 0.86 molPA.molGly-1, and 14.5 g.L-1, respectively, using immobilized cells in the PEI-Poraver bioreactor. The choice of the immobilization matrix can thus significantly influence the fermentation efficiency and -profile. The bioreactor using cells immobilized on PEI-Poraver allowed the fermentation of higher glycerol concentrations and provided stable and higher fermentation rates than that using free cells or the cells immobilized on PEI-Luffa.
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| 9. |
- Dishisha, Tarek, et al.
(författare)
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Bio-based 3-hydroxypropionic- and acrylic acid production from biodiesel glycerol via integrated microbial and chemical catalysis
- 2015
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Background 3-Hydroxypropionic acid (3HP) and acrylic acid (AA) are industrially important platform- and secondary chemical, respectively. Their production from renewable resources by environment-friendly processes is desirable. In the present study, both chemicals were almost quantitatively produced from biodiesel-derived glycerol by an integrated process involving microbial and chemical catalysis. Results Glycerol was initially converted in a fed-batch mode of operation to equimolar quantities of 3HP and 1,3-propanediol (1,3PDO) under anaerobic conditions using resting cells of Lactobacillus reuteri as a biocatalyst. The feeding rate of glycerol was controlled at 62.5 mg/gCDW.h which is half the maximum metabolic flux of glycerol to 3HP and 1,3PDO through the L. reuteri propanediol-utilization (pdu) pathway to prevent accumulation of the inhibitory intermediate, 3-hydroxypronionaldehyde (3HPA). Subsequently, the cell-free supernatant containing the mixture of 3HP and 1,3PDO was subjected to selective oxidation under aerobic conditions using resting cells of Gluconobacter oxydans where 1,3PDO was quantitatively converted to 3HP in a batch system. The optimum conditions for the bioconversion were 10 g/L substrate and 5.2 g/L cell dry weight. Higher substrate concentrations led to enzyme inhibition and incomplete conversion. The resulting solution of 3HP was dehydrated to AA over titanium dioxide (TiO2) at 230 °C with a yield of >95 %. Conclusions The present study represents the first report on an integrated process for production of acrylic acid at high purity and -yield from glycerol through 3HP as intermediate without any purification step. The proposed process could have potential for industrial production of 3HP and AA after further optimization.
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| 10. |
- Dishisha, Tarek, et al.
(författare)
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Flux analysis of the Lactobacillus reuteri propanediol-utilization pathway for production of 3-hydroxypropionaldehyde, 3-hydroxypropionic acid and 1,3-propanediol from glycerol
- 2014
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background Lactobacillus reuteri converts glycerol to 3-hydroxypropionic acid (3HP) and 1,3-propanediol (1,3PDO) via 3-hydroxypropionaldehyde (3HPA) as an intermediate using enzymes encoded in its propanediol-utilization (pdu) operon. Since 3HP, 1,3PDO and 3HPA are important building blocks for the bio-based chemical industry, L. reuteri can be an attractive candidate for their production. However, little is known about the kinetics of glycerol utilization in the Pdu pathway in L. reuteri. In this study, the metabolic fluxes through the Pdu pathway were determined as a first step towards optimizing the production of 3HPA, and co-production of 3HP and 1,3PDO from glycerol. Resting cells of wild-type (DSM 20016) and recombinant (RPRB3007, with overexpressed pdu operon) strains were used as biocatalysts. Results The conversion rate of glycerol to 3HPA by the resting cells of L. reuteri was evaluated by in situ complexation of the aldehyde with carbohydrazide to avoid the aldehyde-mediated inactivation of glycerol dehydratase. Under operational conditions, the specific 3HPA production rate of the RPRB3007 strain was 1.9 times higher than that of the wild-type strain (1718.2 versus 889.0 mg/gCDW.h, respectively). Flux analysis of glycerol conversion to 1,3PDO and 3HP in the cells using multi-step variable-volume fed-batch operation showed that the maximum specific production rates of 3HP and 1,3PDO were 110.8 and 93.7 mg/gCDW.h, respectively, for the wild-type strain, and 179.2 and 151.4 mg/gCDW.h, respectively, for the RPRB3007 strain. The cumulative molar yield of the two compounds was ~1 mol/mol glycerol and their molar ratio was ~1 mol3HP/mol1,3PDO. A balance of redox equivalents between the glycerol oxidative and reductive pathway branches led to equimolar amounts of the two products. Conclusions Metabolic flux analysis was a useful approach for finding conditions for maximal conversion of glycerol to 3HPA, 3HP and 1,3PDO. Improved specific production rates were obtained with resting cells of the engineered RPRB3007 strain, highlighting the potential of metabolic engineering to render an industrially sound strain. This is the first report on the production of 3HP and 1,3PDO as sole products using the wild-type or mutant L. reuteri strains, and has laid ground for further work on improving the productivity of the biotransformation process using resting cells.
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| 11. |
- Dishisha, Tarek, et al.
(författare)
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High cell density sequential batch fermentation for enhanced propionic acid production from glucose and glycerol/glucose mixture using Acidipropionibacterium acidipropionici
- 2024
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Ingår i: Microbial Cell Factories. - 1475-2859. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Propionic acid fermentation from renewable feedstock suffers from low volumetric productivity and final product concentration, which limits the industrial feasibility of the microbial route. High cell density fermentation techniques overcome these limitations. Here, propionic acid (PA) production from glucose and a crude glycerol/glucose mixture was evaluated using Acidipropionibacterium acidipropionici, in high cell density (HCD) batch fermentations with cell recycle. The agro-industrial by-product, heat-treated potato juice, was used as N-source. Results: Using 40 g/L glucose for nine consecutive batches yielded an average of 18.76 ± 1.34 g/L of PA per batch (0.59 gPA/gGlu) at a maximum rate of 1.15 gPA/L.h, and a maximum biomass of 39.89 gCDW/L. Succinic acid (SA) and acetic acid (AA) were obtained as major by-products and the mass ratio of PA:SA:AA was 100:23:25. When a crude glycerol/glucose mixture (60 g/L:30 g/L) was used for 6 consecutive batches with cell recycle, an average of 35.36 ± 2.17 g/L of PA was obtained per batch (0.51 gPA/gC-source) at a maximum rate of 0.35 g/L.h, and reaching a maximum biomass concentration of 12.66 gCDW/L. The PA:SA:AA mass ratio was 100:29:3. Further addition of 0.75 mg/L biotin as a supplement to the culture medium enhanced the cell growth reaching 21.89 gCDW/L, and PA productivity to 0.48 g/L.h, but also doubled AA concentration. Conclusion: This is the highest reported productivity from glycerol/glucose co-fermentation where majority of the culture medium components comprised industrial by-products (crude glycerol and HTPJ). HCD batch fermentations with cell recycling are promising approaches towards industrialization of the bioprocess.
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| 12. |
- Dishisha, Tarek, et al.
(författare)
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Improved propionic acid production from glycerol: combining cyclic batch-and sequential batch fermentations with optimal nutrient composition
- 2015
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 176, s. 80-87
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Tidskriftsartikel (refereegranskat)abstract
- Propionic acid was produced from glycerol using Propionibacterium acidipropionici. In this study, the impact of the concentrations of carbon and nitrogen sources, and of different modes of high cell density fermentations on process kinetics and -efficiency was investigated. Three-way ANOVA analysis and batch cultivations at varying C/N ratios at pH 6.5 revealed that propionic acid production rate is significantly influenced by yeast extract concentration. Glycerol to yeast extract ratio (w w−1) of 3:1 was required for complete glycerol consumption, while maintaining the volumetric productivity. Using this optimum C/N ratio for propionic acid production in cyclic batch fermentation gave propionate yield up to 93 mol% and productivity of 0.53 g L−1 h−1. Moreover, sequential batch fermentation with cell recycling resulted in production rates exceeding 1 g L−1 h−1 at initial glycerol up to 120 g L−1, and a maximum of 1.63 g L−1 h−1 from 90 g L−1 glycerol.
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| 13. |
- Dishisha, Tarek, et al.
(författare)
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Lactobacillus reuteri NAD(P)H oxidase : Properties and coexpression with propanediol-utilization enzymes for enhancing 3-hydroxypropionic acid production from 3-hydroxypropionaldehyde
- 2019
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 0168-1656. ; 289, s. 135-143
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus reuteri metabolizes glycerol through propanediol-utilization (Pdu) pathway to 1,3-propanediol (1,3-PD) via 3-hydroxypropionaldehyde (3-HPA) as intermediate. In the resting cells, the oxidized co-factor obtained in the reaction is regenerated by simultaneous oxidation of 3-HPA to 3-hydroxypropionic acid (3-HP) using propionaldehyde dehydrogenase (PduP), phosphotransacylase (PduL) and propionate kinase (PduW). We have earlier shown that the use of resting cells of recombinant Escherichia coli expressing the oxidative pathway gives the highest theoretical yield of 1 mol 3-HP per mol 3-HPA but is limited by cofactor depletion. In the present study, the gene encoding the enzyme NAD(P)H oxidase (LreuNox) that utilizes molecular oxygen as substrate, was isolated from L. reuteri and heterologously overexpressed in E. coli. LreuNox has a pH optimum of 6 and exhibits Vmax of 101.1 ± 2.2 U/mg with NADH, which is 30% higher than that for NADPH. Co-expression of LreuNox with PduP, PduL and PduW in E. coli enhances the biocatalytic lifetime as well as productivity at least two-fold compared to that achieved without co-factor regeneration.
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| 14. |
- Dishisha, Tarek
(författare)
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Microbial Production of Bio-Based Chemicals: A Biorefinery Perspective
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A shift from fossil- to renewable biomass feedstock for the emerging bio-based economy requires the development and adoption of new sustainable technologies that are more suited for transformation of biomass components to chemicals, materials and energy. This thesis presents investigations on the development of processes based on industrial biotechnology as a key element for the production of chemicals from agro-/industrial by-products. The chemicals of interest are the ones that could potentially serve as building blocks, platforms, for other chemicals and polymers. Glycerol, a by-product of biodiesel production, was used as raw material for the production of propionic acid, 3-hydroxypropionaldehyde (3HPA) and 3-hydroxypropionic acid (3HP), while methacrylic acid (MA) was produced from 2-methyl-1,3-propanediol, a by-product of butanediol production. Different strategies to overcome the bottlenecks such as product inhibition existing in the bioprocesses for production of the chemicals were studied. Fermentation of glycerol to propionic acid was studied using Propionibacterium acidipropionici. High cell density cultivations were used to overcome the low production rate caused by slow microbial growth and product-mediated toxicity. Increasing the cell density by immobilization and sequential batch recycling improved the production rates by 2- and 6-fold, respectively, over that obtained using conventional batch fermentation. Potato juice, a by-product of potato starch processing, was shown to be a promising, inexpensive nitrogen/vitamin source for the growth of the organism and propionic acid production. Lactobacillus reuteri was employed as a whole cell biocatalyst for the conversion of glycerol to 3HPA and 3HP in aqueous solution. Production of 3HPA using glycerol dehydratase activity of the cells, limited by substrate inhibition and product toxicity, was performed in a fed-batch mode with in situ complexation of the hydroxyaldehyde with bisulfite, and subsequent removal through binding to an anion exchanger. This resulted in increase in production of 3HPA from 0.45 g/g biocatalyst in a batch process to 5.4 g/g. 3HP is formed as an oxidation product of 3HPA, however its accumulation as a product of glycerol metabolism in wild-type L. reuteri has not been reported earlier. The metabolic fluxes through the glycerol reductive and oxidative pathways were calculated using variable volume fed-batch operation. The glycerol feeding strategies were optimized to yield complete conversion of 3HPA into equimolar mixture of 3HP and 1,3PDO, the products that can be easily separated from each other. MA was quantitatively produced at high purity from 2-methyl-1,3-propanediol by a novel process involving integrated biological and chemical catalysis. Whole resting cells of Gluconobacter oxydans were used for selective oxidation of the substrate to the corresponding hydroxycarboxylic acid, which upon dehydration over TiO2 at 210 degree Celsius yielded MA. This process offers a potential, significantly greener alternative to the acetone-cyanohydrin process used for MA production, involving highly toxic substrates, large amounts of waste and greenhouse gas emissions.
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| 15. |
- Hatti-Kaul, Rajni, et al.
(författare)
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Lactic acid bacteria : From starter cultures to producers of chemicals
- 2018
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Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 0378-1097 .- 1574-6968. ; 365:20
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Forskningsöversikt (refereegranskat)abstract
- Lactic acid bacteria constitute a diverse group of industrially significant, safe microorganisms that are primarily used as starter cultures and probiotics, and are also being developed as production systems in industrial biotechnology for biocatalysis and transformation of renewable feedstocks to commodity- and high-value chemicals, and health products. Development of strains, which was initially based mainly on natural approaches, is also achieved by metabolic engineering that has been facilitated by the availability of genome sequences and genetic tools for transformation of some of the bacterial strains. The aim of this paper is to provide a brief overview of the potential of lactic acid bacteria as biological catalysts for production of different organic compounds for food and non-food sectors based on their diversity, metabolicand stress tolerance features, as well as the use of genetic/metabolic engineering tools for enhancing their capabilities.
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| 16. |
- Hatti-Kaul, Rajni, et al.
(författare)
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Microbial production of platform chemicals from glycerol
- 2015
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Konferensbidrag (refereegranskat)abstract
- The chemical industry is primarily dependent on fossil oil and gas as raw materials. With increasing demands on reducing the greenhouse gas emissions and carbon footprint attributed to fossil based production, the industry looks for alternative renewable cleaner resources to secure the supplies for future chemical and material products. The current trend in the shift to bio-based economy aims at using the residues and wastes from agricultural-, forest- and marine biomass and related industries as industrial feedstocks. In order to match the efficiency of the petrochemical industry, the biobased industry requires a set of platform chemicals from which a vast range of products can be derived. Organic acids and diols are among the important platform chemicals, many of which are found as intermediates or end products of metabolic pathways in several microbes. In a project sponsored by the Swedish Governmental Agency for Innovation Systems at Lund University, glycerol obtained as a byproduct of biodiesel production, was used as a feedstock for the production of propionic acid (PA), 3-hydroxypropionaldehyde (3HPA), 3-hydroxypropionic acid (3HP) and 1,3-propanediol (1,3PDO), which are potential platforms for important chemicals like methacrylic acid, acrylic acid as well as polymers used in coatings, adhesives, automotive, construction, food, pharmaceuticals, and other industries. PA was produced using Propionibacterium acidipropionici cells. Different strategies for high cell density fermentations have been studied using immobilized cells, sequential batch fermentation and continuous fermentation with cell recycle, resulting in considerable enhancement in volumetric productivities. Heat-treated potato juice turned out to be an inexpensive and efficient nitrogen source for the fermentation. Glycerol is used as an electron acceptor by Lactobacillus reuteri and is metabolized through propanediol-utilization (Pdu) pathway involving initial dehydration to 3HPA, which is subsequently oxidized into 3HP and simultaneously reduced into 1,3PDO. Production of 3HPA by the resting L. reuteri cells was possible by in situ removal of the inhibitory product. Flux analysis of the Pdu pathway was done to determine the optimal conditions for production of 3HPA, and co-production of 3HP and 1,3PDO by the cells. Furthermore, an integrated system for the conversion of glycerol to 3HP and then to acrylic acid was demonstrated.The pdu pathway enzymes catalysing the oxidation of 3HPA were also expressed in Escherichia coli for the production of 3HP. Use of the resting cells led to the quantitative conversion of 3HPA to 3HP while the growing cells gave a mixture of 3HP and 1,3PDO due to the intrinsic 1,3-PD oxidoreductase activity of the E. coli cells. Copexpression of L. reuteri NADH oxidase allowed regeneration of NADH to allow continuous production of 3HP by the resting E. coli cells.ReferencesDishisha T, Alvarez MT, Hatti-Kaul R (2012) Bioresour. Technol. 118, 553-562 Dishisha T, Ståhl Å, Lundmark S, Hatti-Kaul R (2013) Bioresour. Technol. 135, 504-512 Sardari RRR, Dishisha T, Pyo S-H, Hatti-Kaul R (2013) J. Biotechnol. 168, 534-542 Sardari RRR, Dishisha T, Pyo S-H, Hatti-Kaul R (2014) J. Biotechnol. 192, 223-230 Dishisha T, Pereyra LP, Pyo S-H, Britton RA, Hatti-Kaul R (2014) Microb. Cell Fact. 13, 76 Sabet-Azad R, Sardari RRR, Linares-Pastén JA, Hatti-Kaul R (2015) Bioresource Technology 180, 214-221
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| 17. |
- Korany, Ahmed H., et al.
(författare)
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Comparative structural analysis of different mycobacteriophage-derived mycolylarabinogalactan esterases (Lysin B)
- 2019
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Ingår i: Biomolecules. - : MDPI AG. - 2218-273X. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Mycobacteriophage endolysins have emerged as a potential alternative to the current antimycobacterial agents. This study focuses on mycolylarabinogalactan hydrolase (LysB) enzymes of the α/β-hydrolase family, which disrupt the unique mycolic acid layer of mycobacterium cell wall. Multiple sequence alignment and structural analysis studies showed LysB-D29, the only enzyme with a solved three-dimensional structure, to share several common features with esterases (lacking lid domain) and lipases (acting on long chain lipids). Sequence and structural comparisons of 30 LysB homology models showed great variation in domain organizations and total protein length with major differences in the loop-5 motif harboring the catalytic histidine residue. Docking of different p-nitrophenyl ligands (C4-C18) to LysB-3D models revealed that the differences in length and residues of loop-5 contributed towards wide diversity of active site conformations (long tunnels, deep and superficial funnels, shallow bowls, and a narrow buried cave) resembling that of lipases, cutinases, and esterases. A set of seven LysB enzymes were recombinantly produced; their activity against p-nitrophenyl esters could be related to their active site conformation and acyl binding site. LysB-D29 (long tunnel) showed the highest activity with long chain p-nitrophenyl palmitate followed by LysB-Omega (shallow bowl) and LysB-Saal (deep funnel).
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| 18. |
- Pyo, Sang-Hyun, et al.
(författare)
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A new route for the synthesis of methacrylic acid from 2-methyl-1,3-propanediol by integrating biotransformation and catalytic dehydration
- 2012
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Ingår i: Green Chemistry. - 1463-9270. ; 14:7, s. 1942-1948
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Tidskriftsartikel (refereegranskat)abstract
- Methacrylic acid was produced in high yield by an integrated process involving bioconversion of 2-methyl-1,3-propanediol (2M1,3PD) to 3-hydroxy-2-methylpropionic acid (3H2MPA) via 3-hydroxy-2-methylpropanal (3H2MPAL), and catalytic dehydration of the resulting acid. Whole cells of Gluconobacter oxydans grown on glycerol-based culture medium were used as the catalyst for oxidative biotransformation that involved alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) enzymes in the organism. The effect of several reaction parameters on bioconversion in a batch system was investigated to obtain 95–100% conversion of 2M1,3PD with over 95% selectivity to 3H2MPA. The optimum conditions for bioconversion were pH 6–7.5, 25–30 °C, 5–10 g substrate and 2.6 g cell (dry weight) per liter. Higher substrate concentrations led to enzyme inhibition and incomplete conversion. Loss of catalytic activity was noted during recycling of the cells. The cells were active for a longer period when used for biotransformation of 20 g per L of substrate in a continuous reactor with cell retention. The product of the bio-oxidation, 3H2MPA, was converted using titanium dioxide at 210 °C to give methacrylic acid (MA) with a yield of over 85%. The integrated process provides a new environmentally benign route for production of methacrylic acid from 2-methyl-1,3-propanediol, an industrial by-product, compared with the conventional acetone-cyanohydrin (ACH) process.
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| 19. |
- Rezaei, Roya, et al.
(författare)
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Semicarbazide-functionalized resin as a new scavenger for in situ recovery of 3-hydroxypropionaldehyde during biotransformation of glycerol by Lactobacillus reuteri
- 2014
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 192:A, s. 223-230
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Tidskriftsartikel (refereegranskat)abstract
- 3-Hydroxypropionaldehyde (3HPA), a potential C3-platform chemical for a biobased industry, is produced from glycerol using Lactobacillus reuteri through its glycerol dehydratase activity. However, the process is characterized by low yield and productivity due to toxic effects of 3HPA on the biocatalyst activity. In this study, a semicarbazide-functionalized resin was prepared, evaluated for adsorption and in situ recovery of 3HPA during biotransformation of glycerol. Adsorption of 3HPA onto the resin was characterized as “S-curve model”, increasing with increasing initial 3HPA concentration, and reached a maximum of 9.48 mmol/gresin at 71.54 mM 3HPA used. Desorption of 3HPA was evaluated using water and different acids, and was enhanced by acetic acid with organic modifiers. Repeated adsorption–desorption of 3HPA in batch resulted in elution of 13–66.5% of the bound 3HPA during at least three sequential cycles using water and acetic acid, respectively as eluants. Using the resin for in situ product removal led to more than 2 times higher productivity of 3HPA.
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| 20. |
- Romero Soto, Luis, et al.
(författare)
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Metabolic potential of the moderate halophile Yangia sp. ND199 for co-production of polyhydroxyalkanoates and exopolysaccharides
- 2021
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Ingår i: MicrobiologyOpen. - : Wiley. - 2045-8827. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Yangia sp. ND199 is a moderately halophilic bacterium isolated from mangrove samples in Northern Vietnam, which was earlier reported to grow on several sugars and glycerol to accumulate poly(hydroxyalkanoates) (PHA). In this study, the potential of the bacterium for co-production of exopolysaccharides (EPS) and PHA was investigated. Genome sequence analysis of the closely related Yangia sp. CCB-M3 isolated from mangroves in Malaysia revealed genes encoding enzymes participating in different EPS biosynthetic pathways. The effects of various cultivation parameters on the production of EPS and PHA were studied. The highest level of EPS (288 mg/L) was achieved using sucrose and yeast extract with 5% NaCl and 120 mM phosphate salts but with modest PHA accumulation (32% of cell dry weight, 1.3 g/L). Growth on fructose yielded the highest PHA concentration (85% of CDW, 3.3 g/L) at 90 mM phosphate and higher molecular weight EPS at 251 mg/L yield at 120 mM phosphate concentration. Analysis of EPS showed a predominance of glucose, followed by fructose and galactose, and minor amounts of acidic sugars.
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| 21. |
- Sardari, Roya, et al.
(författare)
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Biotransformation of glycerol to 3-hydroxypropionaldehyde: Improved production by in situ complexation with bisulfite in a fed-batch mode and separation on anion exchanger.
- 2013
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 168:4, s. 534-542
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Tidskriftsartikel (refereegranskat)abstract
- 3-Hydroxypropionaldehyde (3HPA) is an important C3 chemical that can be produced from renewable glycerol by resting whole cells of Lactobacillus reuteri. However the process efficiency is limited due to substrate inhibition, product-mediated loss of enzyme activity and cell viability, and also formation of by-products. Complex formation of 3HPA with sodium bisulfite and subsequent binding to Amberlite IRA-400 was investigated as a means of in situ product recovery and for overcoming inhibition. The adsorption capacity and -isotherm of the resin were evaluated using the Langmuir model. The resin exhibited maximum capacity of 2.92mmol complex/g when equilibrated with 45mL solution containing an equilibrium mixture of 2.74mmol 3HPA-bisulfite complex and 2.01mmol free 3HPA. The dynamic binding capacity based on the breakthrough curve of 3HPA and its complex on passing a solution with 2.49mmol complex and 1.65mmol free 3HPA was 2.01mmol/g resin. The bound 3HPA was desorbed from the resin using 0.20M NaCl with a high purity as a mixture of complexed- and free 3HPA at a ratio of 0.77mol/mol. Fed-batch biotransformation of glycerol (818.85mmol) with in situ 3HPA complexation and separation on the bisulfite-functionalized resin resulted in an improved process with consumption of 481.36mmol glycerol yielding 325.54mmol 3HPA at a rate of 17.13mmol/h and a yield of 68 mol%. Also, the cell activity was maintained for at least 28h.
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| 22. |
- Sardari, Roya, et al.
(författare)
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Improved production of 3-Hydroxypropionaldehyde by complex formation with bisulfite during biotransformation of glycerol
- 2013
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 110:4, s. 1243-1248
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Tidskriftsartikel (refereegranskat)abstract
- 3-Hydroxypropionaldehyde (3HPA) is an important specialty chemical which can be produced from glycerol using resting cells of Lactobacillus reuteri. This biocatalytic route, however, suffers from substrate- and product-mediated loss of enzyme activity within 2 h of biotransformation. In order to overcome the inhibitory effects of 3HPA, complex formation with sodium bisulfite was investigated, optimized and applied for in situ capture of the aldehyde during biotransformation of glycerol in a fed-batch process. As a result, the activity of the cells was maintained for at least 18 h. The 3HPA produced per gram cell dry weight was increased 5.7 times compared to the batch production process, and 2.2 times compared to fed-batch process without in situ complex formation. This approach may have potential for production and in situ removal of 3HPA after further process development. Biotechnol. Bioeng. © 2012 Wiley Periodicals, Inc.
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| 23. |
- Sayed, Mahmoud, et al.
(författare)
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Enhanced selective oxidation of trimethylolpropane to 2,2-bis(hydroxymethyl)butyric acid using Corynebacterium sp. ATCC 21245
- 2017
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113. ; 63, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- 2,2-Bis(hydroxymethyl)butyric acid (BHMB) is an important multifunctional chemical for the emerging bio-based polymer industry. It can be produced from trimethylolpropane (TMP) by selective oxidation using growing cells of Corynebacterium sp. ATCC 21245. However, this process is limited by the low volumetric productivity and low concentration of the final product. In the present study, we performed sequential batch operation with cell recycling in media containing glycerol, acetic acid, and increasing concentrations of yeast extract. This approach enhanced the conversion of 10 and 15g/L TMP to 11.0 and 16.3g/L BHMB at rates of 0.50 and 0.20g/L.h, respectively. Applying a cell bleeding strategy resulted in an overall 10-fold improvement in productivity. The consequently prolonged biocatalyst viability resulted in a quantitative conversion of 20g/L TMP to 22.3g/L BHMB and a yield of 1.10gBHMB/gTMP (100% molar yield). This work facilitates further studies of the selective oxidation on other industrially important polyols.
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| 24. |
- Sayed, Mahmoud, et al.
(författare)
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Selective oxidation of trimethylolpropane to 2,2-bis(hydroxymethyl)butyric acid using growing cells of Corynebacterium sp. ATCC 21245.
- 2016
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 221, s. 62-69
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Tidskriftsartikel (refereegranskat)abstract
- Multifunctional chemicals including hydroxycarboxylic acids are gaining increasing interest due to their growing applications in the polymer industry. One approach for their production is a biological selective oxidation of polyols, which is difficult to achieve by conventional chemical catalysis. In the present study, trimethylolpropane (TMP), a trihydric alcohol, was subjected to selective oxidation using growing cells of Corynebacterium sp. ATCC 21245as a biocatalyst and yielding the dihydroxy-monocarboxylic acid, 2,2-bis(hydroxymethyl)butyric acid (BHMB). The study revealed that co-substrates are crucial for this reaction. Among the different evaluated co-substrates, a mixture of glucose, xylose and acetate at a ratio of 5:5:2 was found optimum. The optimal conditions for biotransformation were pH 8, 1v/v/m airflow and 500rpm stirring speed. In batch mode of operation, 70.6% of 5g/l TMP was converted to BHMB in 10 days. For recovery of the product the adsorption pattern of BHMB to the anion exchange resin, Ambersep(®)900 (OH(-)), was investigated in batch and column experiments giving maximum static and dynamic binding capacities of 135 and 144mg/g resin, respectively. BHMB was separated with 89.7% of recovery yield from the fermentation broth. The approach is applicable for selective oxidation of other highly branched polyols by biotransformation.
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| 25. |
- Zaushitsyna, Oksana, et al.
(författare)
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Crosslinked, cryostructured Lactobacillus reuteri monoliths for production of 3-hydroxypropionaldehyde, 3-hydroxypropionic acid and 1,3-propanediol from glycerol
- 2017
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 0168-1656. ; 241, s. 22-32
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Tidskriftsartikel (refereegranskat)abstract
- Crosslinked, cryostructured monoliths prepared from Lactobacillus reuteri cells were evaluated as potential immobilized whole-cell biocatalyst for conversion of glycerol, to potentially important chemicals for the biobased industry, i.e. 3-hydroxypropionaldehyde (3HPA), 3-hydroxypropionic acid (3HP) and 1,3-propanediol (1,3PDO). Glutaraldehyde, oxidized dextran and activated polyethyleneimine/modified polyvinyl alcohol (PEI/PVA) were evaluated as crosslinkers; the latter gave highly stable preparations with maintained viability and biocatalytic activity. Scanning electron microscopy of the PEI/PVA monoliths showed high density of crosslinked cells with wide channels allowing liquid flow through. Flux analysis of the propanediol-utilization pathway, incorporating glycerol/diol dehydratase, propionaldehyde dehydrogenase, 1,3PDO oxidoreductase, phosphotransacylase, and propionate kinase, for conversion of glycerol to the three chemicals showed that the maximum specific reaction rates were −562.6, 281.4, 62.4 and 50.5 mg/gCDW h for glycerol consumption, and 3HPA (extracellular), 3HP and 1,3PDO production, respectively. Under optimal conditions using monolith operated as continuous plug flow reactor, 19.7 g/L 3HPA was produced as complex with carbohydrazide at a rate of 9.1 g/Lh and a yield of 77 mol%. Using fed-batch operation, 1,3PDO and 3HP were co-produced in equimolar amounts with a yield of 91 mol%. The monoliths embedded in plastic carriers showed high mechanical stability under different modes in a miniaturized plug flow reactor.
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