Biofuel bioconversion

Fig. 9.4 Bioconversion (a) and thermochemical (b) platforms flowcharts for 2nd-generation biofuel production. (Adapted from [24]).

Softwoods are the predominant species of tree in Canada. In British Columbia, an estimated 2.2 million t of surplus wood residues are generated each year (5), which until now have been of limited use as a commercial product. Bioconversion of these residues into biofuel ethanol and valuable chemicals provides an attractive opportunity for the sustainable development of both renewable energy and Canada s forest resources. 

Koutinas, A.A., Wang, R.-H. and Webb, C. 2007a. The Biochemurgist - Bioconversion of Agricultural Raw Materials for Chemical Production. Biofuels Bioprod. Biorefi, 1, 24-38. 

One can envisage the future production of liquid fuels and commodity chemicals in a biorefinery Biomass is first subjected to extraction to remove waxes and essential oils. Various options are possible for conversion of the remaining biofeedstock, which consists primarily of lignocellulose. It can be converted to synthesis gas (CO + H2) by gasification, for example, and subsequently to methanol. Alternatively, it can be subjected to hydrothermal upgrading (HTU), affording liquid biofuels from which known transport fuels and bulk chemicals can be produced. An appealing option is bioconversion to ethanol by fermentation. The ethanol can be used directly as a liquid fuel and/or converted to ethylene as a base chemical. Such a hiorefinery is depicted in Fig. 8.1. 

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. 

Menon V, Rao M. (2012). Trends in bioconversion of lignocellulose biofuels, platform chemicals biorefinery concept. Prog Energy Combust Sci, 38, 522-550. 

The brief discussion presented suggests that tanplate-synthesized porous carbons with carefully controlled pore structure may soon find applications in the immobilization of biomolecules (proteins, enzymes, and vitamins) and in bioconversion, reversible amperometric immunosensors, regeneration of enzyme electrodes, switchable biofuel cells, and artificial kidneys [359]. 

Bioreactors are typically considered vessels that produce products in a controlled manner via biological conversion. These systems convert materials (substrates) by influencing metabolic pathways to transform materials into products of interest (Williams 2002). Microbial bioreactors have been used for many years to produce products such as cheese, wine, beer, and bread through traditional fermentation, a process that was studied in depth by the famous microbiologist Louis Pasteur. Current technologies not only produce these products, but also a variety of other products such as industrial solvents (biofuels), biogas, acids, sugars, vitamins, antibiotics, and enzymes for bioconversion processes, as well as other primary and secondary metabolites (Williams 2(X)2 Ullmann 2007). 

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. 

Bioconversion of lignocellulose inhibitors and detoxification. Biotechnol. Biofuels, 6, 16. 

Jonsson, L.J., Alriksson, B., and Nilvebrant, N.-O. (2013) Bioconversion of lignocellulose inhibitors and detoxification. Biotechnol Biofuels,... 

The presence of lignin in plant cell walls interferes with the fermentation to produce biofuels, and enzymes are the single largest processing cost component for bioconversion of biomass after the biomass itself. The transgenic switchgrass requires lower temperature preprocessing and only one-quarter to one-third the level of enzymes... 

Markou, G. Angelidaki, L Georgakakis, D. Microalgal carbohydrates An overview of the factors influencing carbohydrates production, and of main bioconversion technologies for production of biofuels. AppZ. Microbiol. Biotechnol. 2012, 96, 631-645. 

Koutinas, A.A., Wang, R.H., Webb, C., 2007. The biochemurgist - bioconversion of agricultural raw materials for chemical production. Biofuels, Bioproducts and Biorefining 1,24—38. 

Mohammadi, M., et al., 2011. Bioconversion of synthesis gas to second generation biofuels a review. Renewable and Sustainable Energy Reviews 15 (9), 4255—4273. 

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