Biosynthetic enzymes genetic approach

Until recently, most work aimed at optimizing production of valuable secondary metabolites such as antibiotics has consisted of environmental and genetic approaches affecting almost exclusively the levels and catalytic activities of the relevant biosynthetic enzymes, rather than their operational stability. Environmental manipulations have Included (a) the addition of appropriate precursors (b) the disruption of regulatory mechanisms... 

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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