Enhanced production of 2,3-butanediol by engineered Bacillus subtilis

Abstract

Production of 2,3-butanediol by Bacillus subtilis takes place in late-log or stationary phase, depending on the expression of bdhA gene encoding acetoin reductase, which converts acetoin to 2,3-butanediol. The present work focuses on the development of a strain of B. subtilis for enhanced production of 2,3-butanediol in early log phase of growth cycle. For this, the bdhA gene was expressed under the control of P( alsSD ) promoter of AlsSD operon for acetoin fermentation which served the substrate for 2,3-butanediol production. Addition of acetic acid in the medium induced the production of 2,3-butanediol by 2-fold. Two-step aerobic-anaerobic fermentation further enhanced 2,3-butanediol production by 4-fold in comparison to the control parental strain. Thus, addition of acetic acid and low dissolved oxygen in the medium are involved in activation of bdhA gene expression from P( alsSD ) promoter in early log phase. Under the conditions tested in this work, the maximum production of 2,3-butanediol, 2.1 g/l from 10 g/l glucose, was obtained at 24 h. Furthermore, under the optimized microaerophilic condition, the production of 2,3-butanediol improved up to 6.1 g/l and overall productivity increased by 6.7-fold to 0.4 g/l h in the engineered strain compared to that in the parental control.

Production of 2,3-butanediol by a low-acid producing Klebsiella oxytoca NBRF4

“…For biological production of 2,3-BDO using renewable biomass, many microorganisms such as Klebsiella, Enterobacter, Acetobactor, Bacillus and Serratia species were isolated [3], and Klebsiella oxytoca, Enterobacter aerogenes, Escherichia coli and Bacillus subtilis were genetically engineered to modulate the metabolic pathways related to 2,3-BDO production [4][5][6][7]. As a feedstock, glucose, sucrose, crude glycerol, molasses, corn, and whey permeate and hydrolysates of cellulosic and non-cellulosic (e.g.…”

Metabolic engineering of Bacillus subtilis for growth on overflow metabolites

“…The remaining acetoin could block the reverse reaction that would transform the 2.3-butanediol back to acetoin. It has been reported that the presence of acetic acid leads to an increased production of 2.3-butanediol by B. subtilis [19]. In contrast, B. licheniformis is able to utilize acetoin but also 2.3-butanediol entirely (data not shown), which might also have contributed to an increase of biomass.…”

Metabolic engineering of Serratia marcescens MG1 for enhanced production of (3R)-acetoin

“…During the fermentation process, pyruvate produced from the glycolytic pathway was converted into α-acetolactate by α-acetolactate synthase (α-ALS) (Biswas et al 2012). The majority of α-acetolactate was subsequently transformed into ( 3R )-AC catalyzed by α -acetolactate decarboxylase (α-ALDC), while a small amount of α-acetolactate was transformed into diacetyl (DA), by the non-enzymatic oxidation decarboxylation (Liu et al 2011b; Yang et al 2014), and DA could be further converted into ( 3S )-AC which decreased the stereoisomeric purity of ( 3R )-AC.…”