Search

Abstract Background With the increasing stress from oil price and environmental pollution, aroused attention has been paid to the microbial production of chemicals from renewable sources. The C12/14 and C16/18 alcohols are important feedstocks for the production of surfactants and detergents, which are widely used in the most respected consumer detergents, cleaning products and personal care products worldwide. Though bioproduction of fatty alcohols has been carried out in engineered E. coli, several key problems have not been solved in earlier studies, such as the quite low production of C16/18 alcohol, the lack of optimization of the fatty alcohol biosynthesis pathway, and the uncharacterized performance of the engineered strains in scaled-up system. Results We improved the fatty alcohol production by systematically optimizing the fatty alcohol biosynthesis pathway, mainly targeting three key steps from fatty acyl-acyl carrier proteins (ACPs) to fatty alcohols, which are sequentially catalyzed by thioesterase, acyl-coenzyme A (CoA) synthase and fatty acyl-CoA reductase. By coexpression of thioesterase gene BTE, acyl-CoA synthase gene fadD and fatty acyl-CoA reductase gene acr1, 210.1 mg/L C12/14 alcohol was obtained. A further optimization of expression level of BTE, fadD and acr1 increased the C12/14 alcohol production to 449.2 mg/L, accounting for 75.0% of the total fatty alcohol production (598.6 mg/L). In addition, by coexpression of thioesterase gene ‘tesA, acyl-CoA synthase gene fadD and fatty acyl-CoA reductase gene FAR, 101.5 mg/L C16/18 alcohol was obtained, with C16/18 alcohol accounting for 89.2% of the total fatty alcohol production. Conclusions To our knowledge, this is the first report on selective production of C12/14 and C16/18 alcohols by microbial fermentation. This work achieved high-specificity production of both C12/14 and C16/18 alcohols. The encouraging 598.6 mg/L of fatty alcohols represents the highest titer reported so far. In addition, the 101.5 mg/L 89.2% C16/18 alcohol suggests an important breakthrough in C16/18 alcohol production. A more detailed optimization of the expression level of fatty alcohol biosynthesis pathway may contribute to a further improvement of fatty alcohol production.

A new polyoxometalate-based inorganic-organic hybrid compound [(NH3C6H4)2SO2]2SiMo12O40·2CH3CN·CH3OH·2H2O has been synthesized and characterized by IR, UV, elemental analysis, and X-ray crystallography. [(NH3C6H4)2SO2]2+ cation balances the charge on the α-Keggin [SiMo12O40]4- anion. The cooperativity of intermolecular N−H···N, N−H···O, O−H···N and C−H···O hydrogen bonds link the subunits together to form a three-dimensional supramolecular framework. The luminescent properties of the title compound at room temperature were investigated. [ABSTRACT FROM AUTHOR]

Abstract: Two two-dimensional d10-metal-organic frameworks {[CdL2(NO3)2]·(H2O)6} n (1) and {[Zn2L4(NCS)4]·(H2O)4·(CH3OH)} n (2) have been synthesized and characterized by IR, elemental analyses, XRPD, TG technique and complete X-ray single crystal structure analyses, where L is bis(pyridin-3-ylmethylene)biphenyl-2,2′-dicarbohydrazide. The two polymers display similar 2D layer network containing tetranuclear metallacyclic ring units [MII 4L4] (M=Cd (1) and Zn (2)) in the chair conformation, in which each ligand L acts as a bidentate bridging ligand to bind two metal centers through two terminal pyridyl N-donors. The solvent molecules were filled into the macrometallacyclic ring units through multiform hydrogen bonds. In addition, the Cπ interactions are found in the 2D networks and also play an important role in stabilizing the networks. The luminescent properties of 1 and 2 were investigated in the solid state at room temperature. [Copyright &y& Elsevier]