No abstract

Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is an essential electron donor in all organisms. It provides the reducing power that drives numerous anabolic reactions, including those responsible for the biosynthesis of all major cell components and many products in biotechnology. The efficient synthesis of many of these products, however, is limited by the rate of NADPH regeneration. Hence, a thorough understanding of the reactions involved in the generation of NADPH is required to increase its turnover through rational strain improvement. Traditionally, the main engineering targets for increasing NADPH availability have included the dehydrogenase reactions of the oxidative pentose phosphate pathway and the isocitrate dehydrogenase step of the tricarboxylic acid (TCA) cycle. However, the importance of alternative NADPH-generating reactions has recently become evident. In the current review, the major canonical and non-canonical reactions involved in the production and regeneration of NADPH in prokaryotes are described, and their key enzymes are discussed. In addition, an overview of how different enzymes have been applied to increase NADPH availability and thereby enhance productivity is provided.

No abstract

No abstract

This paper describes several examples of knowledge-intensive technologies for the production of chemicals from biomass, which take advantage of the biomass structure in a more efficient way than the production of fuels or electricity alone. The depletion in fossil feedstocks, increasing oil prices, and the ecological problems associated with CO(2) emissions are forcing the development of alternative resources for energy, transport fuels, and chemicals, such as the replacement of fossil resources with CO(2) neutral biomass. Allied with this is the conversion of crude oil products utilizes primary products (ethylene, etc.) and their conversion into either materials or (functional) chemicals with the aid of co-reagents such as ammonia, by various process steps to introduce functionalities such as -NH(2) into the simple structures of the primary products. Conversely, many products found in biomass often contain functionalities. Therefore, it is attractive to exploit this in order to by-pass the use, and preparation of, co-reagents as well as to eliminate various process steps by utilizing suitable biomass-based precursors for the production of chemicals.