Genetically engineered host bacteria have an extensive history for the production of specific proteins including the synthesis of single enzymes for the modification of compounds produced for industrial purposes by biological or chemical processes. Such processes have been developed largely through the process of discovery. The ability to assemble multiple enzymes into synthetic pathways is a new development aided by the synthetic biology approach of constructing and assembling suitable enzymes into pathways that may or may not occur in Nature to provide a highimpact platform for bio-manufacturing of chemicals, biofuels and pharmaceuticals. Industry has depended on chemical catalysts because of the known constraints experienced frequently with biological catalysts but when high stereochemistry, mild synthesis conditions and environmentally friendly processes are significant, application of enzymes is preferred, especially in the case of drug synthesis where enantioselectivity is important. However, many whole cell production processes are beset by toxicity problems, metabolite competition, the production of side products, sub-optimal enzyme ratios and varying temperature optima. As a result, a cell-free biocatalysis allows the manipulation of substrate ratios, provision of regenerated cofactors and adjustment of high energy flux ratios that are difficult or impossible to control in whole cell synthesis. We discuss here the construction of cell free biocatalytic pathways as added free enzymes or multi-enzyme modules that may contain heterologous catalysts. We examine the status of applications leading to commercialisation, emphasizing the importance of economical cofactor regeneration. Nevertheless, problems remain, particularly protein post-translational modifications including glycosylation, phosphorylation, ubiquitination, acetylation, proteolysis, etc. The National Renewable Energy Laboratory and Pacific North West Laboratory have published lists of top value-added chemicals from biomass that include glucaric acid. There have been few reports on the combination of synthetic biology and cell-free protein synthesis to set up pathways for these valuable intermediate compounds. This observation is despite the existence of at least one large scale but specialized cell-free production of antibody conjugates. This review will provide a description of one successful attempt at the cell-free production of glucaric acid and will evaluate progress for other key intermediate and platform chemicals.

Modern research has focused on the microbial transformation of a huge variety of organic compounds to obtain compounds of therapeutic and/or industrial interest. Microbial transformation is a useful tool for producing new compounds, as a consequence of the variety of reactions for natural products. This article describes the production of many important compounds by biotransformation. Emphasis is placed on reporting the metabolites that may be of special interest to the pharmaceutical and biotechnological industries, as well as the practical aspects of this work in the field of microbial transformations.

Streptomyces platensis MA7327 is a bacterium producing interesting antibiotics, which act by the novel mechanism of inhibiting fatty acid biosynthesis. The antibiotics produced by this actinomycete are platensimycin and platencin plus some minor related antibiotics. Platensimycin and platencin have activity against antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus; they also lack toxicity in animal models. Platensimycin also has activity against diabetes in a mouse model. We have been interested in studying the effects of primary metabolites on production of these antibiotics in our chemically defined production medium. In the present work, we tested 32 primary metabolites for their effect. They included 20 amino acids, 7 vitamins and 5 nucleic acid derivatives. Of these, only L-aspartic acid showed stimulation of antibiotic production. We conclude that the stimulatory effect of aspartic acid is due to its role as a precursor involved in the biosynthesis of aspartate-4-semialdehyde, which is the starting point for the biosynthesis of the 3-amino-2,4-dihydroxy benzoic acid portion of the platensimycin molecule.