Biocatalyst-based process advantages

One of the most important advantages of the bio-based processes is operation under mild conditions however, this also poses a problem for its integration into conventional refining processes. Another issue is raised by the water solubility of the biocatalysts and the biocatalyst miscibility in oil. The development of new reactor designs, product or by-product recovery schemes and oil-water separation systems is, therefore, quite important in enabling commercialization. Emulsification is thus a necessary step in the process however, it should be noted that highly emulsified oil can pose significant downstream separation problems. 

The beauty and the economic advantage of the DERA-based processes to certain statin side chains is based on the fact that the carbon skeleton and the two chiral centers of the side chains are built up in one step from the simple, cheap starting materials acetaldehyde and chloroacetaldehyde. This compensates for the higher biocatalyst loading required by the DERA approach compared with the other bio-catalytic processes summarized above, as will be described in the following sections. 

Products synthesized by the parent plant, in a variety of cell types and throughout the development of the plant, are made in culture under a range of conditions and considerable scope exists for improving the productivity of such cultures. Development of stable plant cell lines of sufficiently high productive capacity on which to base commercial processes remains an important problem. Immobilization of plant cells within a support matrix appears to offer both bioengineering and biochemical advantages compared with free cells. These include ease of use in a continuous process with retention of biomass reuse of biocatalyst (cells), cofactors or precursors protection of cells from mechanical stresses and superior productivity and longevity of cells. 

In contrast to rational approaches, the directed evolution of enzymes is based on the search of useful functionalities in libraries randomly generated and on improvement by suitable and proper selection. The directed evolution combines two powerful and independent technologies methods for the generation of random genetic libraries and strategies for the selection of variant enzymes with the specific capabilities [499-503]. This process can result in biocatalysts with non-natural proprieties, since the proteins are expressed in recombinant cells decoupled from its biological functions and evolved under unusual conditions. One additional advantage is the possibility to tailor not only individual proteins, but also the whole biosynthetic and catabohc pathways [471]. 

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