| 1. |
- Butler, Samuel J., et al.
(författare)
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Transglycosylation by β-mannanase TrMan5A variants and enzyme synergy for synthesis of allyl glycosides from galactomannan
- 2022
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113. ; 112, s. 154-166
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Tidskriftsartikel (refereegranskat)abstract
- Retaining β-mannanases are glycoside hydrolases (GHs) that can potentially be applied for synthesis of glycosides by catalysis of transglycosylation reactions. A novel active-site double mutant (R171K/E205D) of the catalytic module (CM) of the family GH5 Trichoderma reesei β-mannanase (TrMan5A) was expressed in Pichia pastoris and purified. TrMan5A, CM and CM-variants R171K and R171K/E205D had pH optima between pH 4.0–5.3 and showed >80 % remaining activity after incubation at 40 °C for 48 h. The enzymes were screened for transglycosylation capacity toward oligomeric and polymeric donor substrates and alcohol acceptors using mass-spectrometry. Hydrolysis and transglycosylation products were analysed by a novel HPLC procedure using an NH2 column. R171K/E205D was superior in reactions with mannotetraose and the acceptor allyl alcohol, it had twice as high propensity for transglycosylation as wild-type TrMan5A. Wild-type TrMan5A produced the highest amounts of allyl β-mannosides (with 1–3 mannosyls) from locust bean galactomannan. Applying enzyme synergy, adding the GH27 guar α-galactosidase to the reaction (to cleave off galactomannan side-groups), gave a 2.1-fold increase of allyl mannosides and simultaneously a significant production of allyl galactopyranoside, increasing overall yield of allyl glycosides 4.4-fold, from 2.2% to 9.8%. The enzymatic synthesis of reactive allyl glycosides opens up for production of novel biomaterials and glycopolymers.
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| 2. |
- Campos, Joana, et al.
(författare)
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Fed-batch strategies for biodetoxification in production of optically pure lactic acid from softwood hydrolysate using Pediococcus acidilactici
- 2023
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113. ; 125, s. 162-170
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Tidskriftsartikel (refereegranskat)abstract
- Optically pure lactic acid (LA) is important for the development of specialized applications for poly-lactic acid (PLA). To pursue sustainable production, feedstocks such as lignocellulosic biomass need to be investigated. The present study focused on the production of L-LA from softwood hydrolysate with Pediococcus acidilactici TY112. One of the challenges when using this substrate is the presence of inhibitors, such as furfural and 5-hydroxymethylfurfural (HMF), formed during pretreatment. To investigate adaptation, fed-batch experiments on softwood hydrolysate and model media were conducted. Although LA production was still affected by the presence of other inhibitors in the hydrolysate, P. acidilactici TY112 was capable of converting HMF and furfural and partly detoxify both hydrolysate and synthetic media. The strain adapted to the inhibitors present, if fed at a low rate (30 mL·h−1 for model medium with inhibitors and 15 mL·h−1 for softwood hydrolysate, both with 30 g·L−1 glucose and 45 g·L−1 mannose). Regarding carbon source consumption, a feeding rate of 30 mL·h−1 limited the uptake of glucose, leading to improved mannose uptake, with LA yields higher than 0.86 g·g−1. This study shows the potential of P. acidilactici TY112 for the production of L-LA from softwood hydrolysate which is regarded as inhibitory.
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| 3. |
- 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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| 4. |
- Chavoshi, Hadi, et al.
(författare)
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Crocin-loaded liposomes sensitize MDA-MB 231 breast cancer cells to doxorubicin by inducing apoptosis
- 2023
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Ingår i: Process Biochemistry. - 1359-5113. ; 130, s. 272-280
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Tidskriftsartikel (refereegranskat)abstract
- Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer with high heterogeneity and poor therapeutic responses to standard treatments. The use of herbal medicine for treatment of TNBC is gaining in popularity worldwide due to their better anti-tumor efficacy and less side effects compared to chemotherapy agents. Previous studies have shown that crocin, a natural carotenoid from saffron, induced cell apoptosis in a concentration-dependent behavior in TNBC MDA-MB-231 breast cancer cells. To improve anti-cancer properties of crocin, liposome-based formulation was prepared by the thin layer hydration-sonication method. The formulation was characterized based on particle size, zeta potential, morphology, encapsulation efficiency (EE) and cellular uptake. The formulation showed monodisperse distribution with an average size of 80 nm, about 70% EE and 11% loading capacity. The effect of crocin, and crocin-loaded liposomes in combination with doxorubicin (DOX) were evaluated using the MDA-MB-231 cell line. The results showed that crocin significantly increased the cytotoxicity of DOX, and crocin loaded liposome enhanced the cytotoxicity further. Flow cytometric analysis revealed that crocin loaded liposome in combination with DOX increased the number of cells in Sub-G1 and G2/M phases. Real time qPCR analysis showed that survivin, cyclin-B1, Bcl-xl mRNA were significantly down-regulated, while Bax and Bid mRNA levels were up-regulated following treatment with crocin loaded liposome compared to control. This study suggested that formulation of crocin into liposomes can be considered as a promising approach against tumor cells, especially when combining with the chemotherapy agent, DOX.
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| 5. |
- El-Sayed, Ashraf S.A., et al.
(författare)
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Production, bioprocess optimization and anticancer activity of Camptothecin from Aspergillus terreus and Aspergillus flavus, endophytes of Ficus elastica
- 2021
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Ingår i: Process Biochemistry. - : Elsevier. - 1359-5113 .- 1873-3298. ; 107, s. 59-73
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Tidskriftsartikel (refereegranskat)abstract
- Attenuating the biosynthetic potency of camptothecin producing fungi with the multiple subculturing and storage is the major challenge that limits the scaling-up of this approach. Thus, screening for novel fungal isolates with reliable metabolic stability and sustainability for camptothecin production is the objective of this work. Among the recovered isolates, Aspergillus terreus (320 μg/l) and A. flavus (290 μg/l) "endophytes of Ficus elastica" were the most potent camptothecin producing isolates. The chemical identity of extracted camptothecin was resolved from the HPLC, NMR, FTIR and LC–MS analyses, with a strong antiproliferative activity against MCF7 (0.18 μM), LS174 T, HCT29 (0.29−0.43 μM), HEPG-2 (0.73 μM) cell lines. The yield of camptothecin was decreased by about > 60 % by the 7th subculturing for both fungal isolates. Upon using Blackett-Burman design to optimize their nutritional requirements by the fungal isolates, their yield of camptothecin were increased by approximately 2 folds, revealing the essentiality of some carbon, nitrogen and growth elicitors for biosynthesis of camptothecin. Interestingly, the biosynthetic machinery of camptothecin by the 7th generation fungal isolates were completely restored upon addition of 1% surface sterilized leaves of F. elastica, while all the other experimented plant extracts did not display any effect on camptothecin production. So, chemicals signals derived from the plant /or its entire microbiome "microbial communication" triggering the expression of camptothecin biosynthetic gene cluster of these fungi, could be the most conceivable hypothesis explaining the attenuation and restoration processes of camptothecin biosynthesis by target the fungal isolates. This is the first report describing the feasibility of A. terreus and A. flavus "endophytes of F. elastica" for camptothecin production with reliable metabolic and sustainable biosynthetic potency upon addition of the plant host's entire microbiome, that could be a preliminary platform for scaling-up of camptothecin production.
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| 6. |
- Gentili, Francesco
(författare)
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Performance of bleaching clays in dechlorophyllisation of microalgal oil: A comparative study
- 2023
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113. ; 129, s. 94-101
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Tidskriftsartikel (refereegranskat)abstract
- While clay has been extensively studied for its ability to remove chlorophyll from vegetable oil, its effects and suitability on microalgae oil have received far less attention. In this study, three different clay types are evaluated and compared for their ability to dechlorophyllise microalgae oil. The clays involved are kaolinite, Fuller's earth and bentonite clay which are activated by acid treatment. Bentonite clay is found to remove chlorophyll effectively (76.04%) than kaolinite and Fuller's earth due to the presence of porous materials that facilitate adsorption. Additionally, the conditions of high temperature (79.69%) and ultrasound treatment (84.24%) demonstrate satisfactory chlorophyll removal efficiency. Another promising finding is that chlorophyll can be adsorbed on the clays without affecting the lipid composition in the microalgae extract significantly. Spent bleaching clay disposal is a growing issue that poses an environmental burden. Reusing bleaching clay can lower expenses and increase oil recovery. In a single sequential run, using spent bentonite clay yields the outcomes comparable to those of virgin bentonite clay. This finding offers a useful green and environmentally friendly approach to remove chlorophyll from microalgae oil feedstock.
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| 7. |
- Hebal, Hakim, et al.
(författare)
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Inhibition of hyperthermostable xylanases by superbase ionic liquids
- 2020
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Ingår i: Process Biochemistry. - : Elsevier. - 1359-5113 .- 1873-3298. ; 95, s. 148-156
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Tidskriftsartikel (refereegranskat)abstract
- The use of enzymes in aqueous solutions of ionic liquids (ILs) could be useful for the enzymatic treatment of lignocellulose. Hydrophilic ILs that dissolve lignocellulose are harmful to enzymes. The toleration limits and enzyme-friendly superbase IL combinations were investigated for the hyperthermophilic Thermopolyspora flexuosa GH10 xylanase (endo-1,4-β-xylanase EC 3.2.1.8) TfXYN10A and Dictyoglomus thermophilum GH11 xylanase DtXYN11B. TfXYN10A was more tolerant than DtXYN11B to acetate or propionate-based ILs. However, when the anion of the ILs was bigger (guaiacolate), GH11 xylanase showed higher tolerance to ILs. 1-Ethyl-3-methylimidazolium acetate ([EMIM]OAc), followed by 1,1,3,3-tetramethylguanidine acetate ([TMGH]OAc), were the most enzyme-friendly ILs for TfXYN10A and [TMGH]+-based ILs were tolerated best by DtXYN11B. Double-ring cations and a large size anion were associated with the strongest enzyme inhibition. Competitive inhibition appears to be a general factor in the reduction of enzyme activity. However, with guaiacolate ILs, the denaturation of proteins may also contribute to the reduction in enzyme activity. Molecular docking with IL cations and anions indicated that the binding mode and shape of the active site affect competitive inhibition, and the co-binding of cations and anions to separate active site positions caused the strongest enzyme inhibition.
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| 8. |
- Mahboubi, Amir, et al.
(författare)
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Concentration-driven reverse membrane bioreactor for the fermentation of highly inhibitory lignocellulosic hydrolysate
- 2020
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Ingår i: Process Biochemistry. - : Elsevier Ltd. - 1359-5113 .- 1873-3298. ; 92, s. 409-416
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Tidskriftsartikel (refereegranskat)abstract
- Optimal production of lignocellulosic bioethanol is hindered due to commonly faced issues with the presence of inhibitory compounds and sequentially consumed sugars in the lignocellulosic hydrolysate. Therefore, in order to find a robust fermentation approach, this study aimed at enhancing simultaneous co-assimilation of sugars, and inhibitor tolerance and detoxification. Therefore, fermentation of toxic wheat straw hydrolysate containing up to 20 g/l furfural, using the concentration-driven diffusion-based technique of reverse membrane bioreactor (rMBR) was studied. The rMBR fermentation of the hydrolysate led to complete furfural detoxification and the conversion of 87 % of sugars into ethanol at a yield of 0.48 g/g. Moreover, when the toxicity level of the hydrolysate was increased to 9 g/l of initial furfural, the system responded exceptionally by reducing 89 % of the inhibitor while only experiencing about 25 % drop in the ethanol yield. In addition, using this diffusion-based set-up in extremely inhibitory conditions (16 g/l furfural), cells could detoxify 40 % of the furfural at a high initial furfural to cell ratio of 9.5:1. The rMBR set-up applied proved that by properly synchronizing the medium condition, membrane area, and inhibitor to cell ratio, some of the shortcomings with conventional lignocellulosic fermentation can be tackled, guaranteeing a robust fermentation.
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