Metabolic engineering recombinant strain

It is worth mentioning that metabolic engineering of E. coli recently provided recombinant strains which synthesized PHAMCL from gluconate. For this, beside phaC2Po or phaClPa> the thioesterase I from E. coli (TesA) [128] or the acyl-ACP thioesterase from Umbellularia californica [129], respectively, were expressed in E. coli. However, the amounts of PHAMCL accumulated in the cells were rather low, and this artificial pathway was not very efficient. 

The phbA, phbB, and phbC genes from Alcaligenes eutrophus (Ralstonia eutrophus) encoding the biosynthetic enzymes (3-ketothiolase, acetoacetyl-CoA reductase (NADPH-dependent), and PHB synthase, respectively, have been cloned into E. coli (Scheme 19.42).339-342 The use of in vitro evolution using error-prone polymerase chain reaction has led to enhanced accumulation of PHA in a resultant recombinant strain.343 Additional studies to enhance the biosynthesis of PHB through the use of metabolic engineering have been discussed.344... 

Seheme4.20 Metabolic engineering route towards the anti-flu drug Oseltamivir (A) and the semi-synthetic cephalosporin Cephalexin (B). Adipoyl-7-ADCAand shikimic acid are produced in recombinant strains of Penicillium chiysogenum and E. coli respectively. 

Mutation/selection, strain recombination (e.g., breeding/protoplast fusion), directed genomic a Ite ration/metabolic engineering/enhance me n t of gene expression rates Amino acid exchange/combinatorial... 

Genetic modification of P. putida is highly relevant for metabolic engineering of producing strains. Modifications of interest consist of deletions and insertions attributing new features to the genome [66]. Such manipulations can be obtained by (i) homologous recombination (mediated by the RecA catalytic activity), (ii) site-specific recombination (subordinated to either the resolvase-invertase family or the FLP-fRT, Cre-loxP family, also referred to as the Int family), and... 

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