Chemicals from Metabolic Pathways

Abstract

For the past 80-90 years petroleum and natural gas have served as raw materials for the majority of the finished products of our daily lives. After World War II these raw materials decisively substituted coal, and they have been the foundation of an enormous increase in material wealth and welfare throughout the World.A few basic raw materials, petroleum, natural gas, þS from oil or natural gas, and O 2 þ N 2 from air, generate first primary (or platform) chemicals, next secondary (commodity) chemicals, then intermediates, and finally the finished products of virtually all industries that provide consumer goods.The aromatic fraction of petroleum delivers platform chemicals, such as propylene, ethyl benzene, cyclohexane, and cumene. These are used to synthesize secondary chemicals such as styrene, adipic acid, caprolactam, acetone, and terephthalic acid; and these in turn are raw materials for the polymer industry that produces textiles, packaging for food products, appliances, and communication equipment (pencils, inks, computer casings, optical fiber). The aliphatic fraction of petroleum contains other platform chemicals (iso-butylene, butadiene, etc.) that supplement the aromatic fraction to produce intermediates for the abovementioned industries. The transportation sector directly receives consumer goods from C 5 to C 14 aliphatic compounds, while products such as antifreeze and gasoline additives are derived by chemical processing of petroleum platform chemicals.Natural gas and cracked naphtha deliver other platform chemicals (ethylene, propylene, CO/H 2 , NH 3 ) for the solvent industry (methanol, ethanol, ethylene glycol, etc.), for the polymer industry (formaldehyde, polyethylene, polypropylene, PVC), and for fertilizers.Together the platform chemicals from petroleum and natural gas are combined to give most of the products of the health and hygiene industry, the housing industry, and the exploding recreation industry. Except for the input from the mining and the forest industry, and the inorganic platform chemicals (such as cement and phosphates) it is, indeed, hard to imagine the modern world without the crucial input from oil and gas.J. Villadsen et al., Bioreaction Engineering Principles,

Metabolic Flux Analysis during the Exponential Growth Phase of Saccharomyces cerevisiae in Wine Fermentations

“…The PPP provides substrates for the synthesis of key products in cellular metabolism. This pathway is involved in the synthesis of nucleic acids (RNA and DNA), some amino acids and the redox carrier NADPH [39], and has been described as growth rate-dependent by different authors [6,23]. Our results showed higher fluxes at the lowest dilution rate used but this fact must be explained by the effect of temperature.…”

“…The flux towards the tri-carboxylic acid cycle (TCA) remained at levels below 1%, which should be enough to maintain the intracellular levels of key metabolic intermediates [39]. This carbon distribution under anaerobic conditions in a Crabtree positive strain has been previously described [32,33] also under winemaking conditions [6,40].…”

Engineering Considerations to Produce Bioactive Compounds from Plant Cell Suspension Culture in Bioreactors

“…When the kinetic model is based on metabolic steps of the reaction, the mathematical complexity increases but leads to a better physical representation of the CSC during the production of PDSM. Besides, the loss of cell viability caused by operational aspects, i.e., a toxic compound, cell shear stress, or cell sintering, is modeled by empirical expressions whose parameters involve physical meaning [138], such as the generalized power law equation (GPLE) [139][140][141]. Finally, the Monod model offers an adequate explanation for the reaction rates of growing cells, but it has no mechanistic basis [142,143].…”

“…Table 6 presents some kinetic models to describe cell growth rate. It is worth mentioning that, in transient experiments, when the concentration of a substrate or PDSM is brusquely modified, Monod kinetics are not suitable and the kinetic model must account for the cell metabolism [138,144]. There are, in the literature, several models that have no mechanistic grounds but account for some biological features of the cell growth [138,145].…”

“…It is worth mentioning that, in transient experiments, when the concentration of a substrate or PDSM is brusquely modified, Monod kinetics are not suitable and the kinetic model must account for the cell metabolism [138,144]. There are, in the literature, several models that have no mechanistic grounds but account for some biological features of the cell growth [138,145]. These models offer an acceptable description of the cell growth and metabolic activity due to fluctuation in the concentration of substrates and products.…”