Photoinduced reactive oxygen species(ROS)-based pollutant removal is one of the ideal solutions to achieve the conversion of solar energy into chemical energy and thus to address environmental pollution.Here,earthabun...Photoinduced reactive oxygen species(ROS)-based pollutant removal is one of the ideal solutions to achieve the conversion of solar energy into chemical energy and thus to address environmental pollution.Here,earthabundant CaCO_(3)-decorated g-C_(3)N_(4)(g-C_(3)N_(4)labeled as CN,CaCO_(3)-decorated g-C_(3)N_(4)sample labeled as CN-CCO)has been constructed by a facile thermal polymerization method for safe and efficient photocatalytic NO removal.The decorated CaCO_(3)as“transit hub”extends theπbonds of CN to deviate from the planes and steers the random charge carriers,which thus provides extra active sites and expedites spatial charge separation to facilitate adsorption/activation of reactants and promote formation of ROS participating in the removal of pollutant.Furthermore,boosted generation of ROS regulates the photocatalytic NO oxidation pathway and thus increases the selectivity of products.NO prefers to be directly oxidized into final product(nitrate)rather than toxic intermediates(NO_(2)),which is well demonstrated by theoretically simulated ROS-based reaction pathways and experimental characterization.The present work promotes the degradation of pollutant and simultaneously suppresses the formation of toxic by-product,which paves the way for ROS-based pollutant removal.展开更多
The purified D-hydantoinase was immobilized on EAH sepharose 4B via the carbodiimide method with a yield of enzyme activity up to 79.44%.The immobilized hydantoinase showed remarkable stability at 4℃.An integrated pr...The purified D-hydantoinase was immobilized on EAH sepharose 4B via the carbodiimide method with a yield of enzyme activity up to 79.44%.The immobilized hydantoinase showed remarkable stability at 4℃.An integrated process of N-carbamoyl-D-phenylalanine(N-D-Phe)synthesis from D,L-5-benzylhydantoin(D,L-BH)catalyzed by immobilized D-hydantoinase coupled with an ion-exchange unit for in situ product removal(ISPR)was established.The variation of pH and conversion in the fixed-bed reactor with or without ISPR was compared at different temperatures,initial substrate concentrations and volumes of adsorbent.Within 24 h,the pH value in the reactor with ISPR could be kept at the alkaline range,which was beneficial to the enzymatic conversion and racemization of L-5-benzyl hydantoinase.This led to a higher overall conversion of 62.725% under optimal operation conditions,an increase of 89.3% compared with the fixed-bed reactor without ISPR.展开更多
For the efficient conversion of L-tyrosine(L-Tyr)to tyrosol,which is an aromatic compound widely used in the pharmaceutical and chemical industries,a novel four-enzyme cascade pathway based on the Ehrlich pathway of S...For the efficient conversion of L-tyrosine(L-Tyr)to tyrosol,which is an aromatic compound widely used in the pharmaceutical and chemical industries,a novel four-enzyme cascade pathway based on the Ehrlich pathway of Saccharomyces cerevisiae was designed and reconstructed in Escherichia coli.Then,the expression levels of the relevant enzymes were coordinated using a modular approach and gene duplication after the identification of the pyruvate decarboxylase from Candida tropicalis(CtPDC)as the rate-limiting enzymatic step.In situ product removal(ISPR)strategy with XAD4 resins was explored to avoid product inhibition and further improve tyrosol yield.As a result,the titer and conversion rate of tyrosol obtained were 35.7 g·L^(-1) and 93.6%,respectively,in a 3-L bioreactor.Results presented here provide a potential enzymatic process for industrial production of tyrosol from cheap amino acids.展开更多
In order to get an industrial strain which can yield a high concentration of lactic acid for ISPR （in situ product removal）, the original strain Rhizopus oryzae RE3303 was mutated by low-energy ion beam implantation...In order to get an industrial strain which can yield a high concentration of lactic acid for ISPR （in situ product removal）, the original strain Rhizopus oryzae RE3303 was mutated by low-energy ion beam implantation. A mutant RK02 was screened, and the factors such as the substrate concentration, nitrogen source concentration, inoculum size, seed age, aeration and temperature that affect the production of lactic acid were studied in detail. Under optimal con- ditions, the maximum concentration of L（＋）-lactic acid reached 34.85 g/L after 30 h shake-flask cultivation without adding any neutralisation （5% Glucose added）, which was a 146% increase in lactic acid production after ion implantation compared with the original strain. It was also shown that RK02 can be used in ISPR to reduce the number of times of separation.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.21822601,21777011)the Fundamental Research Funds for the Central Universities(ZYGX2019Z021)+2 种基金the 111 Project(B20030)the Southwest Petroleum University Graduate Research Innovation Fund Project(2019cxzd008)Shanghai Tongji Gao Tingyao Environmental Science&Technology Development Foundation。
文摘Photoinduced reactive oxygen species(ROS)-based pollutant removal is one of the ideal solutions to achieve the conversion of solar energy into chemical energy and thus to address environmental pollution.Here,earthabundant CaCO_(3)-decorated g-C_(3)N_(4)(g-C_(3)N_(4)labeled as CN,CaCO_(3)-decorated g-C_(3)N_(4)sample labeled as CN-CCO)has been constructed by a facile thermal polymerization method for safe and efficient photocatalytic NO removal.The decorated CaCO_(3)as“transit hub”extends theπbonds of CN to deviate from the planes and steers the random charge carriers,which thus provides extra active sites and expedites spatial charge separation to facilitate adsorption/activation of reactants and promote formation of ROS participating in the removal of pollutant.Furthermore,boosted generation of ROS regulates the photocatalytic NO oxidation pathway and thus increases the selectivity of products.NO prefers to be directly oxidized into final product(nitrate)rather than toxic intermediates(NO_(2)),which is well demonstrated by theoretically simulated ROS-based reaction pathways and experimental characterization.The present work promotes the degradation of pollutant and simultaneously suppresses the formation of toxic by-product,which paves the way for ROS-based pollutant removal.
文摘The purified D-hydantoinase was immobilized on EAH sepharose 4B via the carbodiimide method with a yield of enzyme activity up to 79.44%.The immobilized hydantoinase showed remarkable stability at 4℃.An integrated process of N-carbamoyl-D-phenylalanine(N-D-Phe)synthesis from D,L-5-benzylhydantoin(D,L-BH)catalyzed by immobilized D-hydantoinase coupled with an ion-exchange unit for in situ product removal(ISPR)was established.The variation of pH and conversion in the fixed-bed reactor with or without ISPR was compared at different temperatures,initial substrate concentrations and volumes of adsorbent.Within 24 h,the pH value in the reactor with ISPR could be kept at the alkaline range,which was beneficial to the enzymatic conversion and racemization of L-5-benzyl hydantoinase.This led to a higher overall conversion of 62.725% under optimal operation conditions,an increase of 89.3% compared with the fixed-bed reactor without ISPR.
基金financially supported by the Fundamental Research Funds for the Central Universities (JUSRP21915)National Natural Science Foundation of China (22008089, 21878126)+2 种基金Provincial Natural Science Foundation of Jiangsu Province(BK20200622)the key technologies Research&Development Program of Jiangsu Province (BE2018623)the National First-Class Discipline Program of Light Industry Technology and Engineering(LITE2018-20)
文摘For the efficient conversion of L-tyrosine(L-Tyr)to tyrosol,which is an aromatic compound widely used in the pharmaceutical and chemical industries,a novel four-enzyme cascade pathway based on the Ehrlich pathway of Saccharomyces cerevisiae was designed and reconstructed in Escherichia coli.Then,the expression levels of the relevant enzymes were coordinated using a modular approach and gene duplication after the identification of the pyruvate decarboxylase from Candida tropicalis(CtPDC)as the rate-limiting enzymatic step.In situ product removal(ISPR)strategy with XAD4 resins was explored to avoid product inhibition and further improve tyrosol yield.As a result,the titer and conversion rate of tyrosol obtained were 35.7 g·L^(-1) and 93.6%,respectively,in a 3-L bioreactor.Results presented here provide a potential enzymatic process for industrial production of tyrosol from cheap amino acids.
基金the Eleventh Five-Year Planthe National 863 Program(No.2006AA020101)
文摘In order to get an industrial strain which can yield a high concentration of lactic acid for ISPR （in situ product removal）, the original strain Rhizopus oryzae RE3303 was mutated by low-energy ion beam implantation. A mutant RK02 was screened, and the factors such as the substrate concentration, nitrogen source concentration, inoculum size, seed age, aeration and temperature that affect the production of lactic acid were studied in detail. Under optimal con- ditions, the maximum concentration of L（＋）-lactic acid reached 34.85 g/L after 30 h shake-flask cultivation without adding any neutralisation （5% Glucose added）, which was a 146% increase in lactic acid production after ion implantation compared with the original strain. It was also shown that RK02 can be used in ISPR to reduce the number of times of separation.
