| 1. |
- de Maré, Lena, et al.
(författare)
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A cultivation technique for E. coli fed-batch cultivations operating close to the maximum oxygen transfer capacity of the reactor
- 2005
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Ingår i: Biotechnology Letters. - : Springer Science and Business Media LLC. - 0141-5492 .- 1573-6776. ; 27:14, s. 983-990
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Tidskriftsartikel (refereegranskat)abstract
- A cultivation strategy combining the advantages of temperature-limited fed-batch and probing feeding control is presented. The technique was evaluated in fed-batch cultivations with E. coli BL21(DE3) producing xylanase in a 3 liter bioreactor. A 20% increase in cell mass was achieved and the usual decrease in specific enzyme activity normally observed during the late production phase was diminished with the new technique. The method was further tested by growing E. coli W3110 in a larger bioreactor (50 l). It is a suitable cultivation technique when the O2 transfer capacity of the reactor is reached and it is desired to continue to produce the recombinant protein.
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| 2. |
- Cicortas Gunnarsson, Lavinia, et al.
(författare)
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Evolution of a carbohydrate binding module into a protein-specific binder
- 2006
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Ingår i: Biomolecular Engineering. - : Elsevier BV. - 1389-0344 .- 1878-559X. ; 23:2-3, s. 111-117
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Tidskriftsartikel (refereegranskat)abstract
- A carbohydrate binding module, CBM4-2, derived front the xylanase (Xyn 10A) of Rhodothermus marinus has been used as a scaffold for molecular diversification. Its binding specificity has been evolved to recognise a quite different target, a human monoclonal IgG4. In order to understand the basis for this drastic change in specificity we have further investigated the target recognition of the IgG4-specific CBMs. Firstly, we defined that the structure target recognised by the selected CBM-variants was the protein and not the carbohydrates attached to the glycoprotein. We also identified key residues involved in the new specificity and/or responsible for the swap in specificity, from xylan to human IgG4. Specific changes present in all these CBMs included mutations not introduced in the design of the library from which the specific clones were selected. Reversion of such mutations led to a complete loss of binding to the target molecule, suggesting that they are critical for the recognition of human IgG4. Together with the mutations introduced at will, they had transformed the CBM scaffold into a protein binder. We have thus shown that the scaffold of CBM4-2 is able to harbour molecular recognition for either carbohydrate or protein structures. (c) 2005 Elsevier B.V. All rights reserved.
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| 3. |
- Cicortas Gunnarsson, Lavinia, et al.
(författare)
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Molecular engineering of a thermostable carbohydrate-binding module
- 2006
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Ingår i: Biocatalysis and Biotransformation. - : Informa UK Limited. - 1029-2446 .- 1024-2422. ; 24:1-2, s. 31-37
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Konferensbidrag (refereegranskat)abstract
- Structure-function studies are frequently practiced on the very diverse group of natural carbohydrate-binding modules in order to understand the target recognition of these proteins. We have taken a step further in the study of carbohydrate-binding modules and created variants with novel binding properties by molecular engineering of one such molecule of known 3D-structure. A combinatorial library was created from the sequence encoding a thermostable carbohydrate-binding module, CBM4-2 from a Rhodothermus marinus xylanase, and phage-display technology was successfully used for selection of variants with specificity towards different carbohydrate polymers (birchwood xylan, Avicel (TM), ivory nut mannan and recently also xyloglucan), as well as towards a glycoprotein (human IgG4). Our work not only generated a number of binders with properties that would suite a range of biotechnological applications, but analysis of selected binders also helped us to identify residues important for their specificities.
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| 4. |
- Gunnarsson, Lavinia Cicortas, 1977-, et al.
(författare)
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A carbohydrate binding module as a diversity-carrying scaffold
- 2004
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Ingår i: Protein Engineering Design & Selection. - : Oxford University Press. - 1741-0126 .- 1741-0134. ; 17:3, s. 213-221
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Tidskriftsartikel (refereegranskat)abstract
- The growing field of biotechnology is in constant need of binding proteins with novel properties. Not just binding specificities and affinities but also structural stability and productivity are important characteristics for the purpose of large-scale applications. In order to find such molecules, libraries are created by diversifying naturally occurring binding proteins, which in those cases serve as scaffolds. In this study, we investigated the use of a thermostable carbohydrate binding module, CBM4-2, from a xylanase found in Rhodothermus marinus, as a diversity-carrying scaffold. A combinatorial library was created by introducing restricted variation at 12 positions in the carbohydrate binding site of the CBM4-2. Despite the small size of the library (1.6 x 10(6) clones), variants specific towards different carbohydrate polymers (birchwood xylan, Avicel and ivory nut mannan) as well as a glycoprotein (human IgG4) were successfully selected for, using the phage display method. Investigated clones showed a high productivity (on average 69 mg of purified protein/l shake flask culture) when produced in Escherichia coli and they were all stable molecules displaying a high melting transition temperature (75.7 +/- 5.3 degrees C). All our results demonstrate that the CBM4-2 molecule is a suitable scaffold for creating variants useful in different biotechnological applications.
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| 5. |
- Mårtensson, Olof, et al.
(författare)
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Fermented, ropy, oat-based products reduce cholesterol levels and stimulate the bifidobacteria flora in humans
- 2005
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Ingår i: Nutrition Research. - : Elsevier BV. - 0271-5317. ; 25:5, s. 429-442
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Tidskriftsartikel (refereegranskat)abstract
- This investigation determined the effects of fermented oat-based products containing both native and microbial beta-glucans on plasma lipids and on fecal total bacterial count and Bifidobacterium ssp. The study was randomized, double blind with 3 parallel groups. Sixty-two free-living volunteers with moderately increased plasma cholesterol levels were recruited. In the final analysis, 56 subjects remained, as 6 subjects had left the study either due to lack of time (n = 2), unwillingness to continue the regimen (n = 2), or for other reasons (n = 2). During the first 3 weeks, all subjects received a fermented dairy-based product (control product, run-in period). On the following 5 weeks, I group continued with the control product, whereas the other 2 groups were given fermented oat-based products (intervention period, 3-3.5 g native beta-glucans per day). One of the oat products (ropy) was cofermented with an exopolysaccharide-producing strain, Pediococcus damnosus 2.6. A significant (P = .022) reduction in total cholesterol by 6% was observed in volunteers who had eaten the fermented, ropy, oat-based product compared with the control group. No other significant changes in plasma lipids were found. A significant increase in total bacterial count (P = .001) and Bifidobacterium ssp (P = .012) was observed in fecal samples from volunteers in the group who had eaten the fermented, ropy, oat-based product. This study shows that a fermented, ropy, oat-based product, containing both native and microbial glucans, can reduce the blood cholesterol level and also stimulate the bifidobacteria flora in the gastrointestinal tract. (c) 2005 Elsevier Inc. All rights reserved.
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| 6. |
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| 7. |
- Lindström, Cecilia, et al.
(författare)
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Oral administration of live exopolysaccharide-producing Pediococcus parvulus, but not purified exopolysaccharide suppressed Enterobacteriaceae without affecting bacterial diversity in caecum of mice.
- 2013
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 79:16, s. 5030-5037
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Tidskriftsartikel (refereegranskat)abstract
- Growing evidence indicates that the gut microbiota could have an important role in the development of diet and lifestyle induced diseases. It has been shown that modulation of the gut microbiota by means of probiotics and prebiotics could improve host health. An oat based product fermented by the exopolysaccharide (EPS)-producing Pediococcus parvulus 2.6 has been reported to have a bifidogenic effect. To find out whether the effect could be attributed to the EPS or the bacterium, mice were fed a diet supplemented with 2 % purified EPS or 10(8) CFU/g of live P. parvulus 2.6 for six weeks. Both supplementations altered the gut microbiota composition but in different directions. Purified EPS not only significantly lowered the microbial diversity (P < 0.001) but decreased the bifidobacterial population (P = 0.01). In contrast, the live EPS-producing P. parvulus 2.6 antagonized Enterobacteriaceae without disturbing the homeostasis of the caecal microbiota.
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| 8. |
- Martensson, O, et al.
(författare)
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Growth and exopolysaccharide formation by Pediococcus damnosus 2.6 in beta-glucan suspensions of oat and barley
- 2005
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Ingår i: LWT - Food Science and Technology. - : Elsevier BV. - 0023-6438. ; 38:2, s. 151-155
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Tidskriftsartikel (refereegranskat)abstract
- The formation of exopolysaccharides (EPS) by Pediococcus damnosus strain 2.6 was investigated in two different high P-glucan suspensions of oat (OBC) and barley (BBC). Bacterial growth was confirmed by measuring pH, colony forming units (cfu), viscosity and ropiness during growth. Growth and an increase in viscosity of the beta-glucan suspension based on oat were observed whereas only a minor growth and no significant effect on viscosity was seen in the beta-glucans suspension based on barley. Higher bacterial growth and higher final viscosity and ropiness were observed in samples that were mixed with the OBC and an ordinary commercial oat-base (Adavena(R) G40). These results show the potential of using a combination of a high beta-glucan suspension of cereals to generate fermented products containing both high levels of native beta-glucans from oats or barley and also microbial beta-glucans from the starter culture.
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| 9. |
- Mårtensson, O, et al.
(författare)
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Comparison of growth characteristics and exopolysaccharide formation of two lactic acid bacteria strains, Pediococcus damnosus 2.6 and Lactobacillus brevis G-77, in an oat-based, non-dairy medium.
- 2003
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Ingår i: LWT - Food Science and Technology. - 0023-6438. ; 36:3, s. 353-357
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Tidskriftsartikel (refereegranskat)abstract
- The fermentation characteristics of two strains of lactic acid bacteria (LAB), Lactobacillus brevis G-77 and Pediococcus damnosus 2.6 were compared in an oat-based, nondairy milk medium (Adavena® G40). Viscosity and ropiness were the main growth parameters studied. Both strains are reported to produce an exopolysaccharide (EPS) with a -glucan structure; in addition, the L. brevis strain produces also an EPS with an -glucan structure. Both strains were able to ferment and produce EPS in the oat-based, nondairy medium to the extent that an obvious change was observed in terms of viscosity and ropiness during the fermentation period. These results show the potential of both LAB strains as possible starter cultures in new kinds of fermented, nondairy milk products.
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| 10. |
- Mårtensson, Olof, et al.
(författare)
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Development of an oat-based sour milk-like product
- 2003
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Ingår i: Advances in Food Sciences. - 1431-7737. ; 25:3, s. 100-106
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Tidskriftsartikel (refereegranskat)abstract
- A fermented, oat-based product with properties resembling those of the traditional, Swedish, fermented milk product "filmjoelk" (sour milk) was developed. Com., mixed-strain, mesophilic starter cultures were grown in the oatbases M30, G40, and Oatly, which differed in the compn. of their carbohydrates. The exopolysaccharide-producer Pediococcus damnosus 2.6 was included to increase the viscosity of the G40 product. The CHN-19 culture chosen for the final product formulation produced a pleasant, buttery aroma, but a less sour taste than ordinary "filmjoelk". The addn. of glucose to M30 increased the acidification rate and gave a better aroma. A sensory anal. of two flavored products based on the G40 and M30 media, showed a higher acceptance of the M30 product. This study shows a potential for producing an oat-based "filmjoelk", but further work on consistency and taste is needed.
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