Gene-expression tools for the metabolic engineering of bacteria

Recent advances in metabolic engineering have led to new methods for the sy nthesis of novel molecules, improved production of existing compounds and i mproved degradation of recalcitrant environmental contaminants. Increasing the flux through an existing pathway and introducing a new pathway into a h ost organism demand coordinated expression of the genes that encode the enz ymes, tight control over gene expression and consistent expression in all c ells. Although several gene-expression tools have been developed for the ov erproduction of proteins, they may not be ideal for pathway redirection. Me tabolic engineering requires certain characteristics of gene-expression too ls, and some new tools meet these needs.