Biomass materials, microbiological

While this reaction is substantially exothermic (6), it provides an intriguing approach to the production of fuels from renewable resources, as the required acids (including acetic acid, butyric acid, and a variety of other simple aliphatic carboxylic acids) can be produced in abundant yields by the enzymatic fermentation of simple sugars which are, in turn, available from the microbiological hydrolysis of cellulosic biomass materials ( ] ) These considerations have led us to suggest the concept of a "tandem" photoelectrolysis system, in which a solar photoelectrolysis device for the production of fuels via the photo-Kolbe reaction might derive its acid-rich aqueous feedstock from a biomass conversion plant for the hydrolysis and fermentation of crop wastes or other cellulosic materials (4). 

Other classes of organic materials, such as alkaloids, pigments, resins, sterols, terpenes, terpenoids, and waxes, and many simple organic compounds are often present in various biomass species, but are not discussed here because they are usually present in very small amounts. The peptides present in herbaceous biomass are also not discussed here because, although the nitrogen and sulfur contents of the biomass should be assessed for certain microbiological processes, the amino acids that make up the proteins are generally not important factors in conversion processes. 

Direct estimates of biomass have been attempted by analyzing for molecules or elements that must be of microbiological origin, such as total organic carbon, organic nitrogen, protein, DNA, or ATP. Standard methods are available for all these determinations but their application to autotrophs is complicated by the low cell counts and by interference from biooxidized material. Recently, immunological methods have received attention 4). 

As discussed in Section 5.2 and shown in Table 5.3, the common substrates used in industrial microbiology will be sufficient for today s industrial microbial production processes, but will be far away from meeting the demands for the production of biofuels and bulk chemicals in future. Further on, it will be necessary to use mainly only those substrates which will not be in competition with food or animal feed. Therefore several alternative raw materials substrates have abeady been discussed in literature, for example, related to selected seeds, to biomass, or to biomass-related industrial by-product and waste streams. 

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. 

Some kinds of fiber-forming polypeptides have already been obtained by the microbiological synthesis. In some cases, concentration of these products may reach 40% of the biomass weight and they can be used as a perspective raw material for synthetic fibers. Studies in this direction are widely performed in many countries all over the world. 

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