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- Badary, Amr, et al.
(författare)
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Glycogen Production in Marine Cyanobacterial Strain Synechococcus sp NKBG 15041c
- 2018
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Ingår i: Marine Biotechnology. - : Springer Science and Business Media LLC. - 1436-2228 .- 1436-2236. ; 20:2, s. 109-117
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Tidskriftsartikel (refereegranskat)abstract
- An important feature offered by marine cyanobacterial strains over freshwater strains is the capacity to grow in seawater, replacing the need for often-limited freshwater. However, there are only limited numbers of marine cyanobacteria that are available for genetic manipulation and bioprocess applications. The marine unicellular cyanobacteria Synechococcus sp. strain NKBG 15041c (NKBG15041c) has been extensively studied. Recombinant DNA technologies are available for this strain, and its genomic information has been elucidated. However, an investigation of carbohydrate production, such as glycogen production, would provide information for inevitable biofuel-related compound production, but it has not been conducted. In this study, glycogen production by marine cyanobacterium NKBG15041c was investigated under different cultivation conditions. NKBG15041c yielded up to 399 mu g/ml/OD730 when cells were cultivated for 168 h in nitrogen-depleted medium (marine BG11(Delta N)) after medium replacement (336 h after inoculation). Cultivation under nitrogen-limited conditions also yielded an accumulation of glycogen in NKBG15041c cells (1 mM NaNO3, 301 mu g/ml/OD730; 3 mM NaNO3, 393 mu g/ml/OD730; and 5 mM NaNO3, 328 mu g/ml/OD730) under ambient conditions. Transcriptional analyses were carried out for 13 putative genes responsible for glycogen synthesis and catabolism that were predicted based on homology analyses with Synechocystis sp. PCC 6803 (PCC6803) and Synechococcus sp. PCC7002 (PCC7002). The transcriptional analyses revealed that glycogen production in NKBG15041c under nitrogen-depleted conditions can be explained by the contribution of both increased carbon flux towards glycogen synthesis, similar to PCC6803 and PCC7002, and increased transcriptional levels of genes responsible for glycogen synthesis, which is different from the conventionally reported phenomenon, resulting in a relatively high amount of glycogen under ambient conditions compared to PCC6803 and PCC7002.
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| 3. |
- Yoshimatsu, Keiichi, et al.
(författare)
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Uniform molecularly imprinted microspheres and nanoparticles prepared by precipitation polymerization: The control of particle size suitable for different analytical applications
- 2007
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 1873-4324 .- 0003-2670. ; 584:1, s. 112-121
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Tidskriftsartikel (refereegranskat)abstract
- Molecularly imprinted polymers (MIPs) are being increasingly used as selective adsorbents in different analytical applications. To satisfy the different application purposes, MEN with well controlled physical forms in different size ranges are highly desirable. For examples, MIP nanoparticles are very suitable to be used to develop binding assays and for microfluidic separations, whereas MIP beads with diameter of 1.5-3 mu m can be more appropriate to use in new analytical liquid chromatography systems. Previous studies have demonstrated that imprinted microspheres and nanoparticles can be synthesized using a simple precipitation polymerization method. Despite that the synthetic method is straightforward, the final particle size obtained has been difficult to adjust for a given template. In this work, we initiated to study new synthetic conditions to obtain MIP beads with controllable size in the nano- to micro-meter range, using racemic propranolol as a model template. Varying the composition of the cross-linking monomer allowed the particle size of the MIP beads to be altered in the range of 130 nm to 2.4 mu m, whereas the favorable binding property of the imprinted beads remained intact. The chiral recognition sites were further characterized with equilibrium binding analysis using tritium-labeled (S)-propranolol as a tracer. In general, the imprinted sites displayed a high chiral selectivity: the apparent affinity of the (S)-imprinted sites for (S)-propranolol was 20 times that of for (R)-propranolol. Compared to previously reported irregular particles, the chiral selectivity of competitive radioligand binding assays developed from the present imprinted beads has been increased by six to seven folds in an optimized aqueous solvent. (c) 2006 Elsevier B.V. All rights reserved.
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