已经提出了由木质纤维素生物质生产化学品的替代品。然而,生物质利用的一个固有挑战是底物的异质性,导致水解后存在混合糖。混合糖的发酵通常导致差的产量和多种副产物的产生,因此使随后的下游加工复杂化。因此,近年来已经开发了系统生物催化来应对这一挑战。在这项工作中,使用基于序列的发现方法,鉴定了几种具有广泛底物混杂的新型酶,这些酶是D-木糖和L转化的合适生物催化剂。-阿拉伯糖,植物生物量中半纤维素的两个主要成分。这些混杂酶使得D-木糖和L-阿拉伯糖能够同时进行生物转化,从而以最大的3 g L -1 h -1的产率和> 95%的产率产生1,4-丁二醇(BDO)。使用O 2作为辅因子循环的辅助底物,该模型系统进一步适应于由戊糖生产α-酮戊二酸(2-KG)的最大生产率,达到4.2 g L -1 h -1和99%的产率。为了验证我们系统的潜在适用性,我们尝试扩大D-木糖和L的BDO和2-KG产量-阿拉伯糖。
已经提出了由木质纤维素生物质生产化学品的替代品。然而,生物质利用的一个固有挑战是底物的异质性,导致水解后存在混合糖。混合糖的发酵通常导致差的产量和多种副产物的产生,因此使随后的下游加工复杂化。因此,近年来已经开发了系统生物催化来应对这一挑战。在这项工作中,使用基于序列的发现方法,鉴定了几种具有广泛底物混杂的新型酶,这些酶是D-木糖和L转化的合适生物催化剂。-阿拉伯糖,植物生物量中半纤维素的两个主要成分。这些混杂酶使得D-木糖和L-阿拉伯糖能够同时进行生物转化,从而以最大的3 g L -1 h -1的产率和> 95%的产率产生1,4-丁二醇(BDO)。使用O 2作为辅因子循环的辅助底物,该模型系统进一步适应于由戊糖生产α-酮戊二酸(2-KG)的最大生产率,达到4.2 g L -1 h -1和99%的产率。为了验证我们系统的潜在适用性,我们尝试扩大D-木糖和L的BDO和2-KG产量-阿拉伯糖。
Kinetics and mechanism of the oxidation of some hexoses by sodium N-chlorobenzenesulphonamide in the presence of sodium hydroxide
作者:Tirumala A. Iyengar、Puttaswamy、Dandinasivara S. Mahadevappa
DOI:10.1016/0008-6215(90)84135-h
日期:1990.3
Abstract The kinetics of the oxidation of d -glucose, d -mannose, d -galactose and d -fructose by sodium N -chlorobenzenesulphonamide or Chloramine-B (CAB) in the presence of alkali at 35° has been investigated, and the rate = k [CAB][hexose][HO − ] was observed. The product, benzensulphonamide, had no influence, increase of ionic strength increased the rate, and the rate decreased when the dielectric
Synthesis of 1,2,4-butanetriol enantiomers from carbohydrates
申请人:Frost W. John
公开号:US20060234363A1
公开(公告)日:2006-10-19
A bioengineered synthesis scheme for the production of L-1,2,4-butanetriol, D-1,2,4-butanetriol and racemic mixtures thereof from a carbon source is provided. Methods of producing L-1,2,4-butanetriol, D-1,2,4-butanetriol and racemic mixtures thereof are also provided. Methods are also provided for converting D-1,2,4-butanetriol and L-1,2,4,-butanetriol to D,L-1,2,4-butanetriol trinitrate.
Provided is a method for producing xylonic acid from xylose with a recombinant fungal strain that is genetically modified to express a xylose dehydrogenase gene, which is able to convert xylose to xylonolactone, which is spontaneously or enzymatically hydrolysed to xylonic acid. The xylonic acid is excreted outside the host cell. Xylonate production may be coupled with xylitol production. Alternatively, if xylitol production is not desired, its production is reduced by removing the aldose reductase (or specific xylose reductase) enzyme, which converts xylose to xylitol. Expression of a heterologous lactonase encoding gene may result in higher acid concentrations. The method is suitable for producing xylonic acid from a hemicellulose hydrolysate such as hydrolysed lignocellulosic plant biomass.
Provided is a method for producing xylonic acid from xylose with a recombinant fungal strain that is genetically modified to express a xylose dehydrogenase gene, which is able to convert xylose to xylonolactone, which is spontaneously or enzymatically hydrolyzed to xylonic acid. The xylonic acid is excreted outside the host cell. Xylonate production may be coupled with xylitol production. Alternatively, if xylitol production is not desired, its production is reduced by removing the aldose reductase (or specific xylose reductase) enzyme, which converts xylose to xylitol. Expression of a heterologous lactonase encoding gene may result in higher acid concentrations. The method is suitable for producing xylonic acid from a hemicellulose hydrolysate such as hydrolyzed lignocellulosic plant biomass.
Haloferax volcanii degrades the pentoses D-xylose and L-arabinose via an oxidative pathway to α-ketoglutarate as an intermediate. The initial dehydrogenases of the pathway, D-xylose dehydrogenase (XDH) and L-arabinose dehydrogenase (L-AraDH) catalyze the NADP+ dependent D-xylose and L-arabinose oxidation. It is shown here that the pentoses are oxidized to the corresponding lactones, D-xylono-γ-lactone and L-arabino-γ-lactone, rather than to the respective sugar acids. A putative lactonase gene, xacC, located in genomic vicinity of XDH and L-AraDH, was found to be transcriptionally upregulated by both D-xylose and L-arabinose mediated by the pentose-specific regulator XacR. The recombinant lactonase catalyzed the hydrolysis of D-xylono-γ-lactone and L-arabino-γ-lactone. This is the first report of a functional lactonase involved in sugar catabolism in the domain of archaea.