Metabolic engineering of Saccharomyces cerevisiae for the production of triacetic acid lactone

Javier Cardenas,Nancy A Da Silva

doi:10.1016/j.ymben.2014.07.008

Javier Cardenas, Nancy A Da Silva

Open Access

https://doi.org/10.1016/j.ymben.2014.07.008

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Journal: Metabolic Engineering	Publication Date: Jul 30, 2014
Citations: 81	License type: cc-by

Affiliation: University of California, Irvine

Abstract

Biobased chemicals have become attractive replacements for their fossil-fuel counterparts. Recent studies have shown triacetic acid lactone (TAL) to be a promising candidate, capable of undergoing chemical conversion to sorbic acid and other valuable intermediates. In this study, Saccharomyces cerevisiae was engineered for the high-level production of TAL by overexpression of the Gerbera hybrida 2-pyrone synthase (2-PS) and systematic engineering of the yeast metabolic pathways. Pathway analysis and a computational approach were employed to target increases in cofactor and precursor pools to improve TAL synthesis. The pathways engineered include those for energy storage and generation, pentose biosynthesis, gluconeogenesis, lipid biosynthesis and regulation, cofactor transport, and fermentative capacity. Seventeen genes were selected for disruption and independently screened for their effect on TAL production; combinations of knockouts were then evaluated. A combination of the pathway engineering and optimal culture parameters led to a 37-fold increase in titer to 2.2g/L and a 50-fold increase in yield to 0.13 (g/g glucose). These values are the highest reported in the literature, and provide a 3-fold improvement in yield over previous reports using S. cerevisiae. Identification of these metabolic bottlenecks provides a strategy for overproduction of other acetyl-CoA-dependent products in yeast.

Highlights

The demand for renewable, biobased products as an alternative to those of petroleum origin is rapidly reshaping the scope of biotechnology
Previous research has demonstrated the high tolerance of S. cerevisiae to triacetic acid lactone (TAL) relative to E. coli
To determine the effects on growth, S. cerevisiae strain BY4741 was cultivated in SDC(A) or complex YPD medium containing 1% glucose and spiked with TAL at 5 or 10 glucose was calculated as: [TAL (g/L)

Summary

Introduction

The demand for renewable, biobased products as an alternative to those of petroleum origin is rapidly reshaping the scope of biotechnology. The chemical industry has relied heavily on petroleum resources and chemical catalysis for the production of a wide array of end products (Nikolau et al, 2008). By pulling together biocatalysis and chemical catalysis, valuable chemical intermediates can be synthesized into numerous end products, with biorenewable feedstocks replacing those from fossil-carbon (Nikolau et al, 2008). That TAL can undergo chemical upgrading through a variety of reactions to generate attractive end products like sorbic acid and 1,3-pentadiene that are precursors to preservatives and plastics, respectively. The ability to readily convert TAL into numerous chemicals that are currently produced using petroleum feedstocks (Chia et al, 2012) makes TAL a relevant precursor candidate for microbial synthesis. Developing a biological route for converting sugars directly to TAL will facilitate its use industrially

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