ABSTRACT
6-(N-hydroxyethyl) amino-6-deoxy-l-sorbofuranose (6NSL) is the direct precursor of miglitol for diabetes therapy. The regio- and stereo-selective dehydrogenation offered by the membrane-bound d-sorbitol dehydrogenase (mSLDH) from Gluconobacter oxydans provides an elegant enzymatic method for 6NSL production. In this study, two subunits sldA and sldB of mSLDH were introduced into G. oxydans ZJB-605, and the specific enzyme activity of mSLDH towards NHEG was enhanced by 2.15-fold. However, the endogenous PQQ level was dramatically reduced in the recombinant strain and became a bottleneck to support the holo-enzyme activity. A combined supplementation of four amino acids (Glu, Ile, Ser, Arg) involved in biosynthesis of PQQ in conventional media effectively increased extracellular accumulation of PQQ by 1.49-fold, which further enhanced mSLDH activity by 1.33-fold. The synergic improvement of mSLDH activity provided in this study supports the superior high dehydrogenate activity towards substrate N-2-hydroxyethyl-glucamine, 184.28 g·L-1 of 6NSL was produced after a repeated bioconversion process catalyzed by the resting cells of G. oxydans/pBB-sldAB, all of which presenting a great potential of their industrial application in 6NSL biosynthesis.
Subject(s)
Bacterial Proteins/metabolism , Gluconobacter oxydans/metabolism , L-Iditol 2-Dehydrogenase/metabolism , PQQ Cofactor/biosynthesis , Sorbose/analogs & derivatives , 1-Deoxynojirimycin/analogs & derivatives , 1-Deoxynojirimycin/metabolism , Amino Acids/analysis , Bacterial Proteins/genetics , Bioreactors , Culture Media/chemistry , Fermentation , Gene Expression , Gluconobacter oxydans/enzymology , Gluconobacter oxydans/genetics , Hypoglycemic Agents/metabolism , L-Iditol 2-Dehydrogenase/genetics , PQQ Cofactor/metabolism , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Sorbitol/metabolism , Sorbose/biosynthesisABSTRACT
The aim of this research was to determine the chemical composition of the essential oils of Dahlia pinnata, their insecticidal activity against Sitophilus zeamais and Sitophilusoryzae and to isolate insecticidal constituents. Based on bioactivity-guided fractionation, active constituents were isolated and identified as D-limonene, 4-terpineol and α-terpineol. Essential oils and active compounds tested exhibited contact toxicity, with LD50 values ranging from 132.48 to 828.79 µg/cm(2) against S. zeamais and S. oryzae. Essential oils possessed fumigant toxicity against S. zeamais and S. oryzae with LC50 from 14.10 to 73.46 mg/L. d-Limonene (LC50 = 4.55 and 7.92 mg/L) showed stronger fumigant toxicity against target insects. 4-Terpineol (88 ± 8%) and d-limonene (87 ± 5%) showed the strongest repellency against S. zeamais and S. oryzae, respectively. The results indicate that essential oils and insecticidal constituents have potential for development into natural fumigants, insecticides or repellents for control of the stored-product insect pests.
Subject(s)
Dahlia/chemistry , Insecticides/chemistry , Oils, Volatile/chemistry , Plant Oils/chemistry , Weevils , Animals , Cyclohexane Monoterpenes , Cyclohexenes/chemistry , Cyclohexenes/isolation & purification , Limonene , Menthol/analogs & derivatives , Menthol/chemistry , Menthol/isolation & purification , Monoterpenes/chemistry , Monoterpenes/isolation & purification , Terpenes/chemistry , Terpenes/isolation & purificationABSTRACT
2,4-Dichlorophenol (2,4-DCP) is considered as an important pollutant because of its high toxicity and wide distribution in wastewaters. Innocuous remediation technologies have been studied for the removal of this pollutant. This study investigated the feasibility of using garlic roots as a plant system for the removal of 2,4-DCP. The optimal conditions for its removal were established based on orthogonal experiments (OA25 matrix). Significant factors that affect removal efficiency, arranged from high to low importance, include pH, reaction time, 2,4-DCP concentration, and H2O2 concentration. In addition, garlic roots could be re-used for as much as three consecutive cycles. The decrease in pH and the increase of Cl(-) ion content in the post-removal solutions indicated that 2,4-DCP dehalogenation occurred during transformation. Changes in the deposition pattern of lignin in roots exposed to 2,4-DCP suggested that several of the products deposited were lignin-type polymers. The acute toxicity test revealed that the post-removal solutions were less toxic than the parent solutions. Therefore, garlic roots have considerable potential to effectively and safely remove 2,4-DCP from wastewater.
Subject(s)
Biodegradation, Environmental , Chlorophenols/metabolism , Garlic/metabolism , Plant Roots/metabolism , Water Pollutants, Chemical/metabolism , Biotransformation , Lignin/metabolism , Solutions/metabolismABSTRACT
A cDNA encoding an O-methyltransferase (namely FGCOMT1) was identified from the medicinal plant Trigonella foenum-graecum L. The FGCOMT1 enzyme is a functional caffeic acid O-methyltransferase (COMT) and is localized in the cytosol. Kinetic analysis indicated that FGCOMT1 protein exhibited the highest catalyzing efficiency towards 5-hydroxy ferulic acid and caffeic acid as substrates, but did not possess the abilities to methylate either quercetin or tricetin in vitro. Furthermore, transformation of Arabidopsis loss-of-function Atomt1 mutant with a FGCOMT1 cDNA partially complements accumulation of sinapoyl derivatives but did not function to produce the major methylated flavonol isorhamnetin in seeds. The results from this study indicated that FGCOMT1 is a COMT with substrate preference to monomeric lignin precursors but is not involved in the flavonoid methylation in T. foenum-graecum L.
Subject(s)
Methyltransferases/genetics , Models, Molecular , Phylogeny , Trigonella/enzymology , Amino Acid Sequence , Base Sequence , Caffeic Acids/metabolism , Chromatography, High Pressure Liquid , Cloning, Molecular , Coumaric Acids/metabolism , DNA Primers/genetics , DNA, Complementary/genetics , Flavonoids/biosynthesis , Flavonoids/chemistry , Genetic Complementation Test , Kinetics , Lignin/biosynthesis , Lignin/chemistry , Methyltransferases/chemistry , Methyltransferases/metabolism , Molecular Sequence Data , Molecular Structure , Seeds/metabolism , Sequence Analysis, DNAABSTRACT
Flavonoids belong to a group of plant natural products with variable phenolic structures and play important roles in protection against biotic and abiotic stress. Fenugreek (Trigonella foenum-graecum L.) seeds and stems contain flavonol glycosides and isoflavone derivatives. Up to now, the molecular features of fenugreek flavonoid biosynthesis have not been characterized. Here we present cloning of a cDNA encoding a chalcone isomerase (namely TFGCHI-1) from the leaves of T. foenum-graecum which convert chalcones to flavanones in vitro. Transformation of Arabidopsis loss-of-function TT5 (CHI) mutant with a TFGCHI-1 cDNA complemented TT5 and produced higher levels of flavonol glycosides than wild-type Col-0.
Subject(s)
Intramolecular Lyases/genetics , Plant Proteins/genetics , Trigonella/enzymology , Amino Acid Sequence , Arabidopsis/genetics , Base Sequence , Cloning, Molecular , DNA, Complementary/genetics , Escherichia coli/genetics , Escherichia coli/metabolism , Flavonoids/biosynthesis , Genetic Vectors/genetics , Glycosides/biosynthesis , Intramolecular Lyases/metabolism , Models, Molecular , Molecular Sequence Data , Phylogeny , Plant Proteins/metabolism , Seeds/chemistry , Trigonella/geneticsABSTRACT
A new saponin, malonylginsenoside Ra3, was isolated from the fresh root of Panax ginseng, along with four known ginsenosides. The new compound was identified as (20S)-protopanaxadiol-3-O-(6-O-malonyl-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranoside-20-O-beta-D-xylopyranosyl(1-->3)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranoside on the basis of extensive 1D and 2D NMR as well as HRESI-MS spectroscopic data analysis.