Metabolic engineering of Escherichia coli carrying the hybrid acetone-biosynthesis pathway for efficient acetone biosynthesis from acetate

Abstract

BackgroundThe shortage of food based feedstocks has been one of the stumbling blocks in industrial biomanufacturing. The acetone bioproduction from the traditional acetone–butanol–ethanol fermentation is limited by the non-specificity of products and competitive utilization of food-based substrates. Using genetically modified Escherichia coli to produce acetone as sole product from the cost-effective non-food based substrates showed great potential to overcome these problems.ResultsA novel acetone biosynthetic pathway were constructed based on genes from Clostridium acetobutylicum (thlA encoding for thiolase, adc encoding for acetoacetate decarboxylase, ctfAB encoding for coenzyme A transferase) and Escherichia coli MG1655 (atoB encoding acetyl-CoA acetyltransferase, atoDA encoding for acetyl-CoA: acetoacetyl-CoA transferase subunit α and β). Among these constructs, one recombinant MG1655 derivative containing the hybrid pathway consisting of thlA, atoDA, and adc, produced the highest level of acetone from acetate. Reducing the gluconeogenesis pathway had little effect on acetone production, while blocking the TCA cycle by knocking out the icdA gene enhanced the yield of acetone significantly. As a result, acetone concentration increased up to 113.18 mM in 24 h by the resting cell culture coupling with gas-stripping methods.ConclusionsAn engineered E. coli strain with optimized hybrid acetone biosynthetic pathway can utilize acetate as substrate efficiently to synthesize acetone without other non-gas byproducts. It provides a potential method for industrial biomanufacturing of acetone by engineered E. coli strains from non-food based substrate.Electronic supplementary materialThe online version of this article (10.1186/s12934-019-1054-8) contains supplementary material, which is available to authorized users.

Microbial upgrading of acetate into 2,3-butanediol and acetoin by E. coli W

“…Microbial chemical production from acetate is an emerging eld and commonly relies on the use of complex media additives [17,18,20,21]. Therefore, it was surprising that the addition of yeast extract did not allow 2,3-butanediol and acetoin formation from acetate, but only from yeast extract.…”

“…Comparing this study to recent literature [14,15,17,18] shows that the major difference is the metabolic intermediate, from which the product is derived. While the precursor for other products such as acetone, isopropanol, 3-hydroxypropionic acid and phloroglucinol is acetyl-CoA [14,17,20,21], 2,3-butanediol is derived from pyruvate. Therefore, to produce 2,3-butanediol from acetate, acetate must rst be converted into pyruvate.…”

“…Overexpression of either of these pathways has been shown to increase acetate uptake and product formation [14,17,20,21]. Other strategies that resulted in increased product formation were the deletion of icdA, which led to blocking of the TCA cycle and increased acetone synthesis [21] or deletion of iclR, which activated the glyoxylate shunt and improved 3-hydroxypropionic acid production in combination with acs overexpression [14]. Generally, the glyoxylate shunt is highly active when acetate is used as sole carbon source, whereas the TCA cycle is down-regulated [19].…”

Microbial Upgrading of Acetate into 2,3-Butanediol and Acetoin by E. coli W

“…Acetate uptake in E. coli is possible via two routes: the high a nity, irreversible acetyl-CoA synthetase (acs) or the low a nity, reversible acetate kinase -phosphate acetyl transferase (ackA-pta) system [18]. Overexpression of either of these pathways has been shown to increase acetate uptake and product formation [13,16,19,20]. Other strategies that resulted in increased product formation were the deletion of icdA, which led to blocking of the TCA cycle and increased acetone synthesis [20] or deletion of iclR, which activated the glyoxylate shunt and improved 3-hydroxypropionic acid production in combination with acs overexpression [13].…”

Microbial upgrading of acetate into 2,3-butanediol and acetoin by E. coli W

“…Overexpression of either of these pathways has been shown to increase acetate uptake and product formation (13,16,19,20). Other strategies that resulted in increased product formation were the deletion of icdA, which led to blocking of the TCA cycle and increased acetone synthesis (20) or deletion of iclR, which activated the glyoxylate shunt and improved 3-hydroxypropionic acid production in combination with acs overexpression (13). Generally, the glyoxylate shunt is highly active when acetate is used as sole carbon source, whereas the TCA cycle is down-regulated (18).…”