Glutaric acid is a promising alternative chemical to phthalate plasticizer since it can be produced by the bioconversion of lysine. Though, recent studies have enabled the high‐yield production of ...its precursor, 5‐aminovaleric acid (AMV), glutaric acid production via the AMV pathway has been limited by the need for cofactors. Introduction of NAD(P)H oxidase (Nox) with GabTD enzyme remarkably diminished the demand for oxidized nicotinamide adenine dinucleotide (NAD+). Supply of oxygen through vigorous shaking had a significant effect on the conversion of AMV with a reduced requirement of NAD
+. A high conversion rate was achieved in Nox coupled GabTD reaction under optimized expression vector, terrific broth (TB), and pH 8.5 at high cell density. Supplementary expression of GabD resulted in the production of 353 ± 35 mM glutaric acid with 88.3 ± 8.7% conversion from 400 mM AMV. Moreover, the reaction with a higher concentration of AMV could produce 528 ± 21 mM glutaric acid with 66.0 ± 2.7% conversion. In addition, the co‐biotransformation strategy of GabTD and DavBA whole cells could produce 282 mM glutaric acid with 70.8% conversion from lysine, compared to the 111 mM glutaric acid yield from the combined GabTD–DavBA system.
Glutaric acid is a promising alternative chemical to phthalate plasticizer since it can be produced by the bioconversion of lysine. Though, recent studies have enabled the high‐yield production of its precursor, 5‐aminovaleric acid (AMV), glutaric acid production via the AMV pathway has been limited by the need for cofactors.
5-Aminovaleric acid (5AVA) is an important five-carbon platform chemical that can be used for the synthesis of polymers and other chemicals of industrial interest. Enzymatic conversion of L-lysine to ...5AVA has been achieved by employing lysine 2-monooxygenase encoded by the davB gene and 5-aminovaleramidase encoded by the davA gene. Additionally, a recombinant Escherichia coli strain expressing the davB and davA genes has been developed for bioconversion of L-lysine to 5AVA. To use glucose and xylose derived from lignocellulosic biomass as substrates, rather than L-lysine as a substrate, we previously examined direct fermentative production of 5AVA from glucose by metabolically engineered E. coli strains. However, the yield and productivity of 5AVA achieved by recombinant E. coli strains remain very low. Thus, Corynebacterium glutamicum, a highly efficient L-lysine producing microorganism, should be useful in the development of direct fermentative production of 5AVA using L-lysine as a precursor for 5AVA. Here, we report the development of metabolically engineered C. glutamicum strains for enhanced fermentative production of 5AVA from glucose.
Various expression vectors containing different promoters and origins of replication were examined for optimal expression of Pseudomonas putida davB and davA genes encoding lysine 2-monooxygenase and delta-aminovaleramidase, respectively. Among them, expression of the C. glutamicum codon-optimized davA gene fused with His
-Tag at its N-Terminal and the davB gene as an operon under a strong synthetic H
promoter (plasmid p36davAB3) in C. glutamicum enabled the most efficient production of 5AVA. Flask culture and fed-batch culture of this strain produced 6.9 and 19.7 g/L (together with 11.9 g/L glutaric acid as major byproduct) of 5AVA, respectively. Homology modeling suggested that endogenous gamma-aminobutyrate aminotransferase encoded by the gabT gene might be responsible for the conversion of 5AVA to glutaric acid in recombinant C. glutamicum. Fed-batch culture of a C. glutamicum gabT mutant-harboring p36davAB3 produced 33.1 g/L 5AVA with much reduced (2.0 g/L) production of glutaric acid.
Corynebacterium glutamicum was successfully engineered to produce 5AVA from glucose by optimizing the expression of two key enzymes, lysine 2-monooxygenase and delta-aminovaleramidase. In addition, production of glutaric acid, a major byproduct, was significantly reduced by employing C. glutamicum gabT mutant as a host strain. The metabolically engineered C. glutamicum strains developed in this study should be useful for enhanced fermentative production of the novel C5 platform chemical 5AVA from renewable resources.
A novel Gram-negative, obligate anaerobe, non-motile, flagella-lacking, catalase- and oxidase-negative, coccobacilli-shaped bacterial strain designated AGMB02718
was isolated from swine feces. The ...16S rRNA gene analysis indicated that strain AGMB02718
belonged to the genus
with the highest similarity to
4NBBH2
(= DSM 106860
) (sequence similarity of 96.2%), forming a distinct phylogenetic lineage. Its growth occurred at 25-45°C (optimal 37°C) and in 0.5-1% NaCl (optimal 0.5%). Strain AGMB02718
was asaccharolytic and contained menaquinone 6 (MK-6) and methylmenaquinone 6 (MMK-6) as the predominant respiratory quinones. The major cellular fatty acids in the isolate were C
9
and C
. Based on the whole-genome sequencing analysis, strain AGMB02718
had a 2,606,253 bp circular chromosome with a G + C content of 62.2%. The average nucleotide identity value between strain AGMB02718
and
4NBBH2
was 72.1%, while the digital DNA-DNA hybridization value was 20.9%. Interestingly, genome analysis suggested that strain AGMB02718
possessed a low-toxicity lipopolysaccharide (LPS) because the genome of the isolate does not include
and
genes for Kdo
-Lipid A (KLA) assembly, which confers high toxicity to LPS. Moreover,
macrophage stimulation assay confirmed that AGMB02718
produced LPS with low toxicity. Because the low-toxicity LPS produced by the
family is involved in regulating host immunity and low-toxicity LPS-producing strains can help maintain host immune homeostasis, we evaluated the anti-inflammatory activity of strain AGMB02718
against inflammatory bowel disease (IBD). As a result, strain AGMB02718
was able to prevent the inflammatory response in a dextran sulfate sodium (DSS)-induced colitis model. Therefore, this strain represents a novel species of
that has a protective effect against DSS-induced colitis, and the proposed name is
sp. nov. The type strain is AGMB02718
(=GDMCC 1.2717
= KCTC 25541
).
We report a new class of metal-organic framework (MOF) inks with a water-repellent, photocurable fluoropolymer (PFPE) having up to 90 wt % MOF loading. These MOF inks are enabled to process various ...MOFs through spray coating, pen writing, stencil printing, and molding at room temperature. Upon UV curing, the hydrophobic PFPE matrix efficiently blocks water permeation but allows accessibility of chemicals into the MOF pores, thereby freeing the MOF to perform its unique function. Moreover, by introducing functional MOFs we successfully demonstrated a water-tolerant chemosensor for a class of aromatic pollutants in water and a chemical-resistant thermosensor for visualizing temperature image. This approach would open up innumerable opportunities for those MOFs that are otherwise dormant.
A wide band CMOS LC-tank voltage controlled oscillator (VCO) with small VCO gain ( KVCO ) variation was developed. For small KVCO variation, serial capacitor bank was added to the LC-tank with ...parallel capacitor array. Implemented in a 0.18 mum CMOS RF technology, the proposed VCO can be tuned from 4.39 GHz to 5.26 GHz with the VCO gain variation less than 9.56%. While consuming 3.5 mA from a 1.8 V supply, the VCO has -113.65 dBc/Hz phase noise at 1 MHz offset from the carrier.
Certain plant cells synthesize secondary cell walls besides primary cell walls. This biosynthesis is strictly controlled by an array of transcription factors. Here, we show that SND1, a regulator of ...cell-wall biosynthesis, regulates abscisic acid (ABA) biosynthesis to ensure optimal plant growth. In Arabidopsis, the lack of SND1 and its homolog NST1 leads to the deficiency of secondary cell walls, preventing snd1nst1 double mutant seedlings from growing upright. Compared to wild type seedlings, the snd1 knockout mutant seedlings accumulated less anthocyanin and exhibited low tolerance to salt stress. Compared to wild type seedlings, the snd1 knockout seedlings were more sensitive to salt stress. Although SND1 can bind to the promoter of Myb46, we observed that SND1 binds directly to the promoter of the ABI4 gene, thereby reducing ABA levels under normal growth conditions. Thus, plants adjust secondary cell wall thickening and growth via SND1. SND1 has a dual function: it activates the Myb46 pathway, fostering lignin biosynthesis to produce sufficient cell wall components for growth, while maintaining a low ABA concentration, as it inhibits growth. This dual function of SND1 may help plants modulate their growth efficiently.
With a 17.6 wt% hydrogen content, ammonia is a non-carbon-emitting, easy to store and transport, carrier of hydrogen energy. In this study, an anion-exchange-membrane-based (AEM-based) ...electrochemical cell was used to electrochemically synthesize ammonia from water and nitrogen under ambient conditions. The electrochemical cell was fabricated by attaching Pt/C to both sides of the AEM, and ammonia was generated by supplying nitrogen gas to the cathodic chamber of the cell. AC impedance and current-voltage (I–V) properties were analyzed in relation to the externally applied voltage, and ammonia-formation rates and faradaic efficiencies were determined. The maximum ammonia-formation rate was 1.96×10
−11
mol·s
−1
·cm
−2
at an applied voltage of 2V, with a faradaic efficiency of 0.18%.
Interspecific hybridization occurs among birds, and closely related sister taxa tend to hybridize at a high rate. Genomic hybridization markers are useful for understanding the patterns and processes ...of hybridization and for conserving endangered species in captivity and the wild. In this study, we developed genomic hybridization markers for the F1 progeny of the sister taxa feral pigeons (Columba livia var. domestica) and endangered hill pigeons (Columba rupestris) (family Columbidae). Using whole-genome re-sequencing data, we performed genome-wide analysis for insertion/deletion (InDel) polymorphisms and validated using primers. We conducted polymerase chain reaction (PCR) and agarose gel electrophoresis to identify species-specific InDels. We produced eight F1 hybrids of hill and feral pigeons, and their samples were tested by re-performing analyses and sequencing using 11 species-specific InDel polymorphisms. Eight InDel markers simultaneously amplified two DNA fragments from all F1 hybrids, and there was no abnormality in the sequencing results. The application of genomic tools to detect hybrids can play a crucial role in the assessment of hybridization frequency in the wild. Moreover, systematic captive propagation efforts with hybrids can help control the population decline of hill pigeons.
Cells cultured as monolayers proliferate well, but do not sustain their differentiation characteristics. Previous studies have investigated the interactions between cells and growth factors or ...cytokines by establishing either in vivo or in vitro three-dimensional (3D) cultures. Using porcine uterine epithelial cells and endometrial cells, the current study was designed to develop a 3D uterine culture system and investigate the response to hormone treatment. Formation of the 3D uterine model was similar to that of uterus from the group supplemented with calcium and magnesium, and the addition of these ions altered the spectrum of basement membrane degrading enzyme expression and activity. In particular, the epithelial cell junctions in the 3D model most closely resembled those of an actual uterus when the medium was supplemented with calcium and magnesium; the intercellular basement membrane structure was also tall under these conditions. The study confirmed that Casp-3 expression was lowest in the P4 (progesterone) treatment group, and this hormone was the most potent stimulus for formation of the endometrial cell layer. Therefore, the addition of calcium and magnesium plays an important role in the formation of a 3D uterine model, and the addition of P4 hormone mimics uterine thickening by stimulating growth of the epithelial cell layer.
This paper presents an analysis of magnetic resonance coupling effects that can be considered for realizing a wireless power transfer (WPT) system. In this study, numerical analysis is applied to ...investigate the power transfer characteristics affected by coil inductance and placement. The simulations and experiments, using various coils and positions, are conducted to find the optimum power transfer condition. The experiment shows that the frequency bandwidth of the wireless power transfer at the optimum coupling condition is enlarged to 0.73 MHz and the transfer efficiency is maintained at over 80%.
PDF
