Carbohydrates bioconversions

An alternative approach to the bioconversion of sweet sorghum carbohydrates to ethanol. Biomass and Bioenergy, 8, 99-103. 

The catalytic conversion of platform molecules produced by bioconversion of renewables into bioproducts. This is already the basis of many industrial processes, leading to important tonnages of chemicals and polymers from carbohydrates and triglycerides and fine chemicals from terpenes. This approach needs to be extended and process efficiency should be strengthened by designing more active and selective catalysts. 

Straathof, A.J.J. (1994) Industrially applied bioconversions of carbohydrates. Carbohydrates in Europe, 10, May issne, 5-8. 

Sucrochemistry is already more than 50 years old, and has become a field of carbohydrate chemistry on its own. Indeed, considerable progress has been achieved in the monitoring of the chemical reactivity of sucrose, with the efforts of many research teams who have built on the steps of a few pioneers. Many sucrose derivatives can now be prepared, and sophisticated synthons as well as simple substituted compounds have been reported. However, only a few examples have yet reached the level of the industrial development, and these are mainly in the field of food and cosmetic additives and surfactants. Various polymers, additives for materials, and some chemical intermediates have also been produced. Bioconversions are certainly a major avenue for using sucrose as a starting material, and ethanol production will increase as a consequence of high oil prices. Current awareness of the shortage of fossil resources emphasizes the potential for chemical transformations of sucrose in providing new uses of this abundant natural resource. 

Therefore, this bioconversion does not lose any atoms of carbohydrate or produce any carbon dioxide. For the conversion of pentoses, the stoichiometry can be expressed as ... 

D-Xylose, the second most abundant carbohydrate after o-glucose, is used to produce xylitol, a health-friendly food sweetener, which has also been recognized as one of the Top value added chemicals from biomass [37]. It is a source of rare sugars applying bioconversion methodologies [38]. 

The carbohydrate precursor to staurosporine has been shown to be D-glucose and the N- and O-methyl groups are derived from L-methionine as shown in Scheme 2. Hoehn reported the isolation of 15b by cofermentation and bioconversion studies and found that O-methylation is the last step, ie., direct precursor to staurosporine bios)mthesis [37]. 

Finally, the non-renewability of petroleum will eventually provide an opportunity for chemicals from biomass. Much of the transformation for this purpose will be microbiological and the raw materials will be carbohydrate polymers. Here the impact of the new biology in the form of genetic engineering for optimized yield and process promises exciting new concepts in chemical production. Bioconversion processes already represent economically feasible methods for producing basic organic chemicals based on renewable raw materials. 

Table 7. Bioconversion of other carbohydrates by various fungal species...

Table 11. Effect of aeration bioconversion of carbohydrates by fungi...

In this communication we extend our prior observations and demonstrate the use of xylan-rich, hemicellulosic residual fractions of wood for the production of P(3HB-co-3HV) by B. cepacia. Levulinic acid, the secondary carbon source utilized in this bioconversion process, can be produced cost-effectively from a vast array of renewable carbohydrate-rich resources including cellulose-containing forest and agricultural waste residues 24,25). This five-carbon cosubstrate (4-ketovaleric acid) serves as a precursor to the 3-hydroxyvalerate (3HV) component of the B. cepacia-dtnved P(3HB-co-3HV) copolymer (Figure 1). Further, the mol % 3HV composition and associated physical/mechanical properties of the copolymer can be manipulated as a function of the substrate concentrations provided in the fermentation. Physical-chemical characterizations of such PHA copolymers are reported herein, as evidence supporting the potential of these biodegradable thermoplastics to serve as viable replacements for conventional, environmentally recalcitrant commodity plastics. 

Mamma, D., Christakopoulos, R, Koullas, D., Kekos, D., Maoris, B. J., Kouki, E. An alternative approach to the bioconversion of sweet sorghum carbohydrates to ethanol. Biomass Bioenerg. 1995, 8, 99-103. 

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. 

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