Biofuel production fermentation

Chen F, Dixon RA. 2007. Lignin modification improves fermentable sugar yields for biofuel production. Nature Biotech 25 759-761. 

Here the typical example is the inhibitor effect of ethanol on yeast growth. Considerable efforts are made by the biocompanies to develop yeast strains that are tolerant to high ethanol concentrations since this will give considerable savings in, e.g., production of biofuel by fermentation. 

Although CO2 is inhibitory to microbes, compressed hydrocarbon solvents may be appropriate for extractive bioconversions and extractions in biphasic (aqueous-compressed solvent) systems. Our laboratory investigated the metabolic activity of the anaerobic, thermophilic bacteria Clostridium ther-mocellum as a model system (45). Thermophilic bacteria have a distinct advantage over conventional yeasts for ethanol production in their ability to use a variety of inexpensive biomass feedstocks. Extractive fermentation using compressed solvents is an approach to address the end-product toxicity of these bacteria to ethanol and improve the economic viability of biofuel production by thermophilic organisms. 

One of the most abundant natural and renewable sources of carbon is cellulose, fibers that have been used for centuries in the production of paper. Chemists have found ways to modify these water-insoluble fibers, applying various chemical or biochemical treatments that generate high value materials (modified cellulose). The latter find applications in medicine, in material sciences, and in the nanotechnologies, including production of absorbers to remove undesired and toxic contaminants from factory effluents. Chemical and biochemical modifications of cellulose generate materials that can be used to produce ethanol (biofuel) by fermentation. 

The world market prices for the petroleum- and biobased components are in the same range for raw materials and intermediates, but when using the biobased compounds for production of the petroleum-based intermediates, they will face the disadvantage to have to compete on a cost basis against processes which have been optimized for a long time, and which often run on depreciated capital. Further it becomes obvious that the amount of the recently available biobased materials will not be sufficient to meet the demands of biofuel production and the chemical industry. Additionally most of the biobased substrates recently used as substrates for microbial fermentations are in competition with food and feed and may not be used in big scale in future for the production of biofuels and chemicals. 

Enzymes can convert lignocellulosic biomass into a suitable fermentation feed-stock for biofuel production. Different yeast strains are used for ethanol production, such as S. diastaticus, Candida sp., S. cerevisiae and K. marxianus, as well as different bacteria such as Zymomonas mobilis. The employment of distillation is desirable for food grade purity of applications other than that of biofuel. In fact, batch fermentation was coupled with a membrane distillation process developed with the application of a membrane distillation bioreactor for ethanol production. Meanwhile,... 

Extractant Design for Enhanced Biofuel Production through Fermentation of Cellulosic Wastes... 

The industrial and agricultural wastes are rich in cellulosic substrates, so they can be fermented to give renewable fuels within a zero emission framework (UIgiati, 2(K)1). This waste treatment option produces clean alternatives to fossil fuels, while using wastes that would otherwise be landfilled. The environmental benefits of this scheme are significant, but reduction of the production cost is considered essential to make the biofuel products competitive in the open market (Wyman, 2001). 

Bioresource Technology. 1979- Amsterdam Elsevier (0960-8524). Online ScienceDirect. Topics include biofuels production, modeling and economics bioprocesses and bioproducts biocatalysis and fermentations biomass and feedstocks utilization and thermal conversion of biomass combustion, pyrolysis, gasification, catalysis. 

Biotechnology for Biofuels. 2007- London BioMed Central Ltd. (1754-6834). Online http // www.biotechnologyforbiofuels.com/. An open access online journal publishing research on advances in the production of biofuels from biomass, including development of plants for biofuels production, plant deconstruction, pretreatment and fractionation, enzyme production and enzymatic conversion, and fermentation and bioconversion. 

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