TY - JOUR

T1 - Engineering a short, aldolase based pathway for (R)-1,3-butanediol production in Escherichia coli

AU - Nemr, Kayla

AU - Muller, Jonas

AU - Joo, Jeong Chan

AU - Gawand, Pratish

AU - Cjoudhary, Ruhi

AU - Mendonca, Burton

AU - Lu, Shuyi

AU - Yu, Xiuyan

AU - Yakunin, Alexander

AU - Mahadevan, Radhakrishnan

PY - 2018/7/1

Y1 - 2018/7/1

N2 - Microbial processes can produce a wide range of compounds; however, producing complex and long chain hydrocarbons remains a challenge. Aldol condensation offers a direct route to synthesize these challenging chemistries and can be catalyzed by microbes using aldolases. Deoxyribose-5-phosphate aldolase (DERA) condensesaldehydes and/or ketones to beta-hydroxyaldehydes, which can be further converted to value-added chemicals such as a precursor to cholesterol-lowering drugs. Here, we implement a short, aldolase-based pathway in Escherichia coli to produce (R)-1,3-BDO from glucose, an essential component of pharmaceutical products and cosmetics. First, we expressed a three step heterologous pathway from pyruvate to produce 0.3 g/L of (R)-1,3-BDO with a yield of 11.2 mg/g of glucose in wild-type E. coli K12 MG1655. We used a systems metabolic engineering approach to improve (R)-1,3-BDO titer and yield by: 1) identifying and reducing major by-products: ethanol, acetoin, and 2,3-butanediol; 2) increasing pathway flux through DERA to reduce accumulation of toxic acetaldehyde. We then implemented a two stage fermentation process to improve (R)-1,3-BDO titer by 8-fold to 2.4 g/L and yield by 5-fold to 56 mg/g of glucose (11% of maximum theoretical yield), by controlling pH to 7 and higher dissolved oxygen level. Furthermore, this study highlights the potential of the aldolase chemistry to synthesize diverse products directly from renewable resources in microbes.

AB - Microbial processes can produce a wide range of compounds; however, producing complex and long chain hydrocarbons remains a challenge. Aldol condensation offers a direct route to synthesize these challenging chemistries and can be catalyzed by microbes using aldolases. Deoxyribose-5-phosphate aldolase (DERA) condensesaldehydes and/or ketones to beta-hydroxyaldehydes, which can be further converted to value-added chemicals such as a precursor to cholesterol-lowering drugs. Here, we implement a short, aldolase-based pathway in Escherichia coli to produce (R)-1,3-BDO from glucose, an essential component of pharmaceutical products and cosmetics. First, we expressed a three step heterologous pathway from pyruvate to produce 0.3 g/L of (R)-1,3-BDO with a yield of 11.2 mg/g of glucose in wild-type E. coli K12 MG1655. We used a systems metabolic engineering approach to improve (R)-1,3-BDO titer and yield by: 1) identifying and reducing major by-products: ethanol, acetoin, and 2,3-butanediol; 2) increasing pathway flux through DERA to reduce accumulation of toxic acetaldehyde. We then implemented a two stage fermentation process to improve (R)-1,3-BDO titer by 8-fold to 2.4 g/L and yield by 5-fold to 56 mg/g of glucose (11% of maximum theoretical yield), by controlling pH to 7 and higher dissolved oxygen level. Furthermore, this study highlights the potential of the aldolase chemistry to synthesize diverse products directly from renewable resources in microbes.

U2 - 10.1016/j.ymben.2018.04.013

DO - 10.1016/j.ymben.2018.04.013

M3 - Article

VL - 48

SP - 13

EP - 24

JO - Metabolic Engineering

JF - Metabolic Engineering

ER -