Removal of noxious dyes is gaining public and technological attention. Herein grafting polymerization was employed to produce a novel adsorbent using acrylic acid and carboxymethyl cellulose for dye removal. Scanning ...Removal of noxious dyes is gaining public and technological attention. Herein grafting polymerization was employed to produce a novel adsorbent using acrylic acid and carboxymethyl cellulose for dye removal. Scanning electron microscopy and Fourier-transform infrared spectroscopy verified the adsorbent formed under optimized reaction conditions. The removal ratio of adsorbent to Methyl Orange, Disperse Blue 2BLN and malachite green chloride reached to 84.2%, 79.6% and 99.9%, respectively. The greater agreement between the calculated and experimental results suggested that pseudo second-order kinetic model better represents the kinetic adsorption data. Equilibrium adsorptions of dyes were better explained by the Temkin isotherm. The results implied that this new cellulose-based absorbent had the universaiity for removal of dyes through the chemical adsorption mechanism.展开更多
The production ofβ-amyrin in Saccharomyces cerevisiae is still low due to the inability of effectively regulating the endogenous metabolic pathway for competitive synthesis ofβ-amyrin precursors.In this study,we foc...The production ofβ-amyrin in Saccharomyces cerevisiae is still low due to the inability of effectively regulating the endogenous metabolic pathway for competitive synthesis ofβ-amyrin precursors.In this study,we focused on two branches ofβ-amyrin synthetics pathway that consumeβ-amyrin precursors(2,3-oxidosqualene and cytosolic acetyl-CoA)and regulated related genes(ADH1,ADH4,ADH5,ADH6,CIT2,MLS2 and ERG7).We developed a CRISPRi method by constructing a multi-gRNA plasmid to down-regulate the seven genes simultaneously,which is reported for the first time in S.cerevisiae.The average transcription inhibition efficiency of the seven genes reached as high as 75.5%.Furthermore,by optimizing the fermentation condition(including pH,inoculum size,initial glucose concentration and feed of glucose or ethanol)and increasing extracellular transportation via supplying methyl-β-cyclodextrin,β-amyrin concentration of engineered strain SGibSdCg increased by 44.3%compared with the parent strain SGib,achieving 156.7 mg/L which was the highest concentration ofβ-amyrin reported in yeast.The one-step down-regulation of multiple genes using CRISPRi showed high efficiency and promising future in improving the yields of natural products.展开更多
基金supported by the National High Technology Research and Development Program of China(863 Program,2015AA034601)the Natural Science Foundation of Yunnan Province(2016FB084)+1 种基金the Scientific Research Foundation of the Department of Education of Yunnan Province(2015Z003)the Open Fund of Yunnan Key Laboratory for Micro/nano Materials&Technology(ZZ2016006)~~
基金financially supported by the National Natural Science Foundation of China(No.21104047)the Outstanding Young Innovative Fund of Xinjiang Bingtuan,China(No.2010JC25)
文摘Removal of noxious dyes is gaining public and technological attention. Herein grafting polymerization was employed to produce a novel adsorbent using acrylic acid and carboxymethyl cellulose for dye removal. Scanning electron microscopy and Fourier-transform infrared spectroscopy verified the adsorbent formed under optimized reaction conditions. The removal ratio of adsorbent to Methyl Orange, Disperse Blue 2BLN and malachite green chloride reached to 84.2%, 79.6% and 99.9%, respectively. The greater agreement between the calculated and experimental results suggested that pseudo second-order kinetic model better represents the kinetic adsorption data. Equilibrium adsorptions of dyes were better explained by the Temkin isotherm. The results implied that this new cellulose-based absorbent had the universaiity for removal of dyes through the chemical adsorption mechanism.
基金the funds support from National Natural Science Foundation of China(21576027,21425624,21736002,21566032).
文摘The production ofβ-amyrin in Saccharomyces cerevisiae is still low due to the inability of effectively regulating the endogenous metabolic pathway for competitive synthesis ofβ-amyrin precursors.In this study,we focused on two branches ofβ-amyrin synthetics pathway that consumeβ-amyrin precursors(2,3-oxidosqualene and cytosolic acetyl-CoA)and regulated related genes(ADH1,ADH4,ADH5,ADH6,CIT2,MLS2 and ERG7).We developed a CRISPRi method by constructing a multi-gRNA plasmid to down-regulate the seven genes simultaneously,which is reported for the first time in S.cerevisiae.The average transcription inhibition efficiency of the seven genes reached as high as 75.5%.Furthermore,by optimizing the fermentation condition(including pH,inoculum size,initial glucose concentration and feed of glucose or ethanol)and increasing extracellular transportation via supplying methyl-β-cyclodextrin,β-amyrin concentration of engineered strain SGibSdCg increased by 44.3%compared with the parent strain SGib,achieving 156.7 mg/L which was the highest concentration ofβ-amyrin reported in yeast.The one-step down-regulation of multiple genes using CRISPRi showed high efficiency and promising future in improving the yields of natural products.
