Showing papers on "2,3-Butanediol published in 2017"

Process Development for Enhanced 2,3-Butanediol Production by Paenibacillus polymyxa DSM 365

Abstract: While chiral 2,3-Butanediol (2,3-BD) is currently receiving remarkable attention because of its numerous industrial applications in the synthetic rubber, bioplastics, cosmetics, and flavor industries, 2,3-BD-mediated feedback inhibition of Paenibacillus polymyxa DSM 365 limits the accumulation of higher concentrations of 2,3-BD in the bioreactor during fermentation. The Box-Behnken design, Plackett-Burman design (PBD), and response surface methodology were employed to evaluate the impacts of seven factors including tryptone, yeast extract, ammonium acetate, ammonium sulfate, glycerol concentrations, temperature, and inoculum size on 2,3-butanediol (2,3-BD) production by Paenibacillus polymyxa DSM 365. Results showed that three factors; tryptone, temperature, and inoculum size significantly influence 2,3-BD production (p < 0.05) by P. polymyxa. The optimal levels of tryptone, inoculum size, and temperature as determined by the Box-Behnken design and response surface methodology were 3.5 g/L, 9.5%, and 35 °C, respectively. The optimized process was validated in batch and fed-batch fermentations in a 5-L Bioflo 3000 Bioreactor, and 51.10 and 68.54 g/L 2,3-BD were obtained, respectively. Interestingly, the production of exopolysaccharides (EPS), an undesirable co-product, was reduced by 19% when compared to the control. These results underscore an interplay between medium components and fermentation conditions, leading to increased 2,3-BD production and decreased EPS production by P. polymyxa. Collectively, our findings demonstrate both increased 2,3-BD titer, a fundamental prerequisite to the potential commercialization of fermentative 2,3-BD production using renewable feedstocks, and reduced flux of carbons towards undesirable EPS production.

Efficient (3R)-Acetoin Production from meso-2,3-Butanediol Using a New Whole-Cell Biocatalyst with Co-Expression of meso-2,3-Butanediol Dehydrogenase, NADH Oxidase, and Vitreoscilla Hemoglobin

Abstract: Acetoin (AC) is a volatile platform compound with various potential industrial applications. AC contains two stereoisomeric forms: (3S)-AC and (3R)-AC. Optically pure AC is an important potential intermediate and widely used as a precursor to synthesize novel optically active materials. In this study, chiral (3R)-AC production from meso-2,3-butanediol (meso-2,3-BD) was obtained using recombinant Escherichia coli cells co-expressing meso-2,3-butanediol dehydrogenase (meso-2,3-BDH), NADH oxidase (NOX), and hemoglobin protein (VHB) from Serratia sp. T241, Lactobacillus brevis, and Vitreoscilla, respectively. The new biocatalyst of E. coli/pET-mbdh-nox-vgb was developed and the bioconversion conditions were optimized. Under the optimal conditions, 86.74 g/l of (3R)-AC with the productivity of 3.61 g/l/h and the stereoisomeric purity of 97.89% was achieved from 93.73 g/l meso-2,3-BD using the whole-cell biocatalyst. The yield and productivity were new records for (3R)-AC production. The results exhibit the industrial potential for (3R)-AC production via whole-cell biocatalysis.

High production of 2,3-butanediol from glycerol without 1,3-propanediol formation by Raoultella ornithinolytica B6.

Abstract: Conversion of crude glycerol derived from biodiesel processes to value-added chemicals has attracted much attention. Herein, Raoultella ornithinolytica B6 was investigated for the high production of 2,3-butanediol (2,3-BD) from glycerol without 1,3-propanediol (1,3-PD) formation, a by-product hindering 2,3-BD purification. By evaluating the effects of temperature, agitation speed, and pH control strategy, the fermentation conditions favoring 2,3-BD production were found to be 25 °C, 400 rpm, and pH control with a lower limit of 5.5, respectively. Notably, significant pH fluctuations which positively affect 2,3-BD production were generated by simply controlling the lower pH limit at 5.5. In fed-batch fermentation under those conditions, R. ornithinolytica B6 produced 2,3-BD up to 79.25 g/L, and further enhancement of 2,3-BD production (89.45 g/L) was achieved by overexpressing homologous 2,3-BD synthesis genes (the budABC). When pretreated crude glycerol was used as a sole carbon source, R. ornithinolytica B6 overexpressing budABC produced 78.10 g/L of 2,3-BD with the yield of 0.42 g/g and the productivity of 0.62 g/L/h. The 2,3-BD titer, yield, and productivity values obtained in this study are the highest 2,3-BD production from glycerol among 1,3-PD synthesis-deficient 2,3-BD producers, demonstrating R. ornithinolytica B6 as a promising 2,3-BD producer from glycerol.

Metabolic engineering of Klebsiella pneumoniae based on in silico analysis and its pilot-scale application for 1,3-propanediol and 2,3-butanediol co-production

Abstract: Klebsiella pneumoniae naturally produces relatively large amounts of 1,3-propanediol (1,3-PD) and 2,3-butanediol (2,3-BD) along with various byproducts using glycerol as a carbon source. The ldhA and mdh genes in K. pneumoniae were deleted based on its in silico gene knockout simulation with the criteria of maximizing 1,3-PD and 2,3-BD production and minimizing byproducts formation and cell growth retardation. In addition, the agitation speed, which is known to strongly affect 1,3-PD and 2,3-BD production in Klebsiella strains, was optimized. The K. pneumoniae ΔldhA Δmdh strain produced 125 g/L of diols (1,3-PD and 2,3-BD) with a productivity of 2.0 g/L/h in the lab-scale (5-L bioreactor) fed-batch fermentation using high-quality guaranteed reagent grade glycerol. To evaluate the industrial capacity of the constructed K. pneumoniae ΔldhA Δmdh strain, a pilot-scale (5000-L bioreactor) fed-batch fermentation was carried out using crude glycerol obtained from the industrial biodiesel plant. The pilot-scale fed-batch fermentation of the K. pneumoniae ΔldhA Δmdh strain produced 114 g/L of diols (70 g/L of 1,3-PD and 44 g/L of 2,3-BD), with a yield of 0.60 g diols per gram glycerol and a productivity of 2.2 g/L/h of diols, which should be suitable for the industrial co-production of 1,3-PD and 2,3-BD.

Production of High Levels of Chirally Pure d-2,3-Butanediol with a Newly Isolated Bacillus Strain

Abstract: 2,3-Butanediol (2,3-BD), especially when it exists in the chirally pure form, is a valuable chemical feedstock with numerous applications in various industries However, in most cases, the 2,3-BD naturally produced by the microorganism is a mixture of two of the three isomers (d-2,3-BD, l-2,3-BD, and meso-2,3-BD), which has restricted applications and thus a much lower value than the chirally pure one In this study, we report a new isolate Bacillus spp FJ-4 strain, which can produce highly chirally pure d-2,3-BD (>999%) to high levels, with very high productivity and yield The composition of the fermentation medium for the strain was sequentially optimized using statistical experimental methodologies During a fed-batch experiment, 1000 g/L of d-2,3-BD was produced from 2268 g/L glucose, with a yield of 044 g/g (882% of the theoretical maximum) Acetoin was the primary byproduct, and no other byproduct such as lactate, acetate, or ethanol was detected, which would be advantageous for the downstrea

Effect of deletion of 2,3-butanediol dehydrogenase gene (bdhA) on acetoin production of Bacillus subtilis.

Abstract: The present work aims to block 2,3-butanediol synthesis in acetoin fermentation of Bacillus subtilis. First, we constructed a recombinant strain BS168D by deleting the 2,3-butanediol dehydrogenase gene bdhA of the B. subtilis168, and there was almost no 2,3-butanediol production in 20 g/L of glucose media. The acetoin yield of BS168D reached 6.61 g/L, which was about 1.5 times higher than that of the control B. subtilis168 (4.47 g/L). Then, when the glucose concentration was increased to 100 g/L, the acetoin yield reached 24.6 g/L, but 2.4 g/L of 2,3-butanediol was detected at the end of fermentation. The analysis of 2,3-butanediol chiral structure indicated that the main 2,3-butanediol production of BS168D was meso-2,3-butanediol, and the bdhA gene was only responsible for (2R,3R)-2,3-butanediol synthesis. Therefore, we speculated that there may exit another pathway relating to the meso-2,3-butanediol synthesis in the B. subtilis. In addition, the results of low oxygen condition fermentation showed that deletion of bdhA gene successfully blocked the reversible transformation between acetoin and 2,3-butanediol and eliminated the effect of dissolved oxygen on the transformation.

Bacterial strain producing 2,3-butanediol and other metabolites

Abstract: The present invention provides a modified strain of the bacterium Lactococcus lactis obtainable by a method that comprises a step of fusion of two protoplasts from two Lactococcus lactis parental strains which, compared to the wild type strain of Lactococcus lactis from which they derive, show: (a) an increased ability to produce acetoin and/or 2,3- butanediol (2,3-BDO), and (b) a decreased ability to produce lactic acid, when cultured under aerobic conditions, and wherein the modified strain of Lactococcus lactis has an increased ability to produce 2,3-BDO of at least 20 times the amount produced by the wild type strain, an increased ability to produce acetoin of at least 20 times the amount produced by the wild type strain and a decreased ability to produce lactic acid of at least 10 times the amount produced by the wild type strain, when cultured under aerobic conditions. Also provided are methods to produce acetoin and 2,3- BDO..

Method for promoting microorganisms to synthesize 2,3-butanediol by adding amino acid

Abstract: The invention discloses a method for promoting microorganisms to synthesize 2,3-butanediol by adding an amino acid. The method for promoting the microorganisms to synthesize the 2,3-butanediol by adding the amino acid comprises the following steps that (1) a seed medium of paenibacillus polymyxa is prepared, the activated paenibacillus polymyxa is inoculated into the seed medium to be subjected to seed cultivation, and a paenibacillus polymyxa seed solution is prepared; (2) a fermentation medium of the paenibacillus polymyxa is prepared, the amino acid is added into the fermentation medium before seed solution is inoculated, and the initial concentration of the amino acid is 0.5-2.5 g / L; and (3) the paenibacillus polymyxa seed solution prepared in the step (1) is inoculated into the fermentation medium prepared in the step (2) to be subjected to fermental cultivation. According to the method for promoting the microorganisms to synthesize the 2,3-butanediol by adding the amino acid, by adding the amino acid with the specific concentration into the fermentation medium, the bacteria growth mass of the paenibacillus polymyxa in the fermentation process is increased and moreover, the metabolic activity in bacterial cells is vigorous; and the synthesis capability to the target product 2,3-butanediol is promoted, and the use ratio of the bacterial cells to substrates, the yield of the target product and the productivity are increased.

Microbial Production of 2,3- Butanediol From Waste Glycerol

Abstract: An inevitable waste from biodiesel production is glycerol, contaminated by alkaline catalyst, water and methanol and released in quite big amounts, exceeding its market demand. One way of its utilization is production of different bulk and fine chemicals, for example 2,3butanediol. The latter is used as a precursor for manufacturing of plastics, synthetic rubber, some pharmaceuticals, etc. In the present paper the ability of the strain Klebsiella oxytoca VA 8391 to produce this compound under batch and fed-batch conditions was studied at initial glycerol concentrations between 10 and 30 g dm. Experiments have been carried out in shaking flasks. The bacteria cultivation was at 37C and stirred conditions at 200 rpm, whereas the product formation was studied both under stirred and still conditions. It was found out that the used strain is capable to produce selectively 2,3butanediol with very high yields of practical importance (up to 92 %) and no contamination by other products. The optimum glycerol concentration was 20 g dm. At higher initial concentrations substrate inhibition started to occur. It was established that the studied fermentation process required aerobic bacteria cultivation followed by anoxic period of product formation by the developed culture. Only in this case high yields were attained.

Method for improving yield of acetoin and 2,3-butanediol by mixed fermentation

Abstract: The invention discloses a method for improving the yields of acetoin and 2,3-butanediol by mixed fermentation. The method comprises the following steps: inoculating a Paenibucillus polymyxa GJX-518 seed of which the preservation number is CGMCC (China General Microbiological Culture Collection Center) NO. 7096 into a fermentation culture medium according to the inoculation density of biomass 0.1 to 0.4, culturing for 10 to 15h, and inoculating a high-yield riboflavin escherichia coli engineered strain EC-Rib 02 seed to continue fermentation, wherein the biomass ratio of the Paenibucillus polymyxa GJX-518 to the high-yield riboflavin escherichia coli engineered strain EC-Rib02 is 1:(1 to 4). According to the method disclosed by the invention, production cost can be reduced, and the yields of the acetoin and the 2,3-butanediol can be improved.