Development of a commercial scale process for production of 1,4-butanediol from sugar.

A sustainable bioprocess for the production of 1,4-butanediol (BDO) from carbohydrate feedstocks was developed. BDO is a chemical intermediate that goes into a variety of products including automotive parts, electronics, and apparel, and is currently manufactured commercially through energy-intensive petrochemical processes using fossil raw materials. This review highlights the development of an Escherichia coli strain and an overall process that successfully performed at commercial scale for direct production of bio-BDO from dextrose. Achieving such high level performance required an integrated technology platform enabling detailed engineering of enzyme, pathway, metabolic network, and organism, as well as development of effective fermentation and downstream recovery processes.

An integrated biotechnology platform for developing sustainable chemical processes.

Genomatica has established an integrated computational/experimental metabolic engineering platform to design, create, and optimize novel high performance organisms and bioprocesses. Here we present our platform and its use to develop E. coli strains for production of the industrial chemical 1,4-butanediol (BDO) from sugars. A series of examples are given to demonstrate how a rational approach to strain engineering, including carefully designed diagnostic experiments, provided critical insights about pathway bottlenecks, byproducts, expression balancing, and commercial robustness, leading to a superior BDO production strain and process.

Metabolic engineering of Escherichia coli for direct production of 1,4-butanediol.

1,4-Butanediol (BDO) is an important commodity chemical used to manufacture over 2.5 million tons annually of valuable polymers, and it is currently produced exclusively through feedstocks derived from oil and natural gas. Herein we report what are to our knowledge the first direct biocatalytic routes to BDO from renewable carbohydrate feedstocks, leading to a strain of Escherichia coli capable of producing 18 g l(-1) of this highly reduced, non-natural chemical. A pathway-identification algorithm elucidated multiple pathways for the biosynthesis of BDO from common metabolic intermediates. Guided by a genome-scale metabolic model, we engineered the E. coli host to enhance anaerobic operation of the oxidative tricarboxylic acid cycle, thereby generating reducing power to drive the BDO pathway. The organism produced BDO from glucose, xylose, sucrose and biomass-derived mixed sugar streams. This work demonstrates a systems-based metabolic engineering approach to strain design and development that can enable new bioprocesses for commodity chemicals that are not naturally produced by living cells.

Use of glnQ as a counterselectable marker for creation of allelic exchange mutations in group B streptococci.

Efficient allelic exchange mutagenesis in group B streptococci (GBS) has been hampered by the lack of a counterselectable marker system. Growth inhibition of GBS by the glutamine analog gamma-glutamyl hydrazide requires glnQ. We have used this phenomenon to create a counterselectable marker system for efficient selection of allelic exchange mutants in GBS.