2,3-Butanediol

About: 2,3-Butanediol is a research topic. Over the lifetime, 299 publications have been published within this topic receiving 6016 citations. The topic is also known as: Pseudobutylene glycol & Dimethylene glycol.

2,3-Dihydroxyisovalerate production by Klebsiella pneumoniae.

Abstract: 2,3-Dihydroxyisovalerate is an intermediate of valine and leucine biosynthesis pathway; however, no natural microorganism has been found yet that can accumulate this compound. Klebsiella pneumoniae is a useful bacterium that can be used as a workhorse for the production of a range of industrially desirable chemicals. Dihydroxy acid dehydratase, encoded by the ilvD gene, catalyzes the reaction of 2-ketoisovalerate formation from 2,3-dihydroxyisovalerate. In this study, an ilvD disrupted strain was constructed which resulted in the inability to synthesize 2-ketoisovalerate, yet accumulate 2,3-dihydroxyisovalerate in its culture broth. 2,3-Butanediol is the main metabolite of K. pneumoniae and its synthesis pathway and the branched-chain amino acid synthesis pathway share the same step of the α-acetolactate synthesis. By knocking out the budA gene, carbon flow into the branched-chain amino acid synthesis pathway was upregulated, which resulted in a distinct increase in 2,3-dihydroxyisovalerate levels. Lactic acid was identified as a by-product of the process and by blocking the lactic acid synthesis pathway, a further increase in 2,3-dihydroxyisovalerate levels was obtained. The culture parameters of 2,3-dihydroxyisovalerate fermentation were optimized, which include acidic pH and medium level oxygen supplementation to favor 2,3-dihydroxyisovalerate synthesis. At optimal conditions (pH 6.5, 400 rpm), 36.5 g/L of 2,3-dihydroxyisovalerate was produced in fed-batch fermentation over 45 h, with a conversion ratio of 0.49 mol/mol glucose. Thus, a biological route of 2,3-dihydroxyisovalerate production with high conversion ratio and final titer was developed, providing a basis for an industrial process. Key Points • A biological route of 2,3-dihydroxyisovalerate production was setup. • Disruption of budA causes 2,3-dihydroxuisovalerate accumulation in K. pneumoniae. • Disruption of ilvD prevents 2,3-dihydroxyisovalerate reuse by the cell. • 36.5 g/L of 2,3-dihydroxyisovalerate was obtained in fed-batch fermentation.

2,3‐Butanediol Production by Immobilized Cells of Enterobacter sp.a

Abstract: After the Second World War, there was little interest in production of 2,3-butanediol by fermentation until the late 1970s. 2,3-Butanediol may be used for the production of 1,3-butadiene, which can be used for making polybutadiene and styrene-butadiene gums. Butadiene can be produced from ethanol,’ but its production directly from 2,3-butanediol is cheaper.’ It can also be used as liquid fuel because of its great fuel value (27.2 MJ/kg). 2,3-Butanediol can be produced by many different microorganisms, but only a few species are suitable for industrial production. Typical 2,3-butanediol producers are Enterobacter, Klebsiella. Serratia. Aeromonas and some Bacillus spp. The formation of 2.3-butanediol is connected to the production of acetoin, ethanol, acetic acid, lactic acid, formic acid and succinic acid.’ The above-mentioned organisms are able to use pentoses and pentitols as their only carbohydrate source. Enterobacter aerogenes resembles Klebsiella pneumoniae, and they were earlier regarded as the same strain. Chua et a/.4 produced 2,3-butanediol using K-carrageenan bead-entrapped cells with glucose as substrate. The cells were not as sensitive to pH, temperature, and dissolved oxygen as the native cells. Furthermore, the formation of acetoin was significantly lower with immobilized cells. The production rate in a shake flask fermentation was 0.5 g/dm’/h and the yield was 60% of the theoretical value. In the continuous fermentation, the yield was 50% of the theoretical value, and 3 g/dm’ could be produced at least for 10 days. Chambers et aLs used, for 2,3-butanediol production, a bacterium isolated from decaying wood. Immobilizing cells on 12-mm Rasching rings, they were able to convert a 100 g/dm’ xylose solution at a rate three times as great as that for their conventional batch reactor. We have studied 2.3-butanediol production with immobilized cells. The organism, isolated from paper mill process waters, was identified as Enterobacter sp., and was shown to be the best 2,3-butanediol producer together with Klebsiella pneumoniae. Nutrients were supplied by Difco Labs. (USA), sodium alginate by BDH Chemicals (England), gelatin by Riedel de Haen AG (FRG), cellulose diacetate by Eastman Kodak Co. (USA), nylon net by 3M Co. (USA). Xylose was obtained from China. Enterobacter sp. free cells were cultivated by batch fermentation (unless otherwise mentioned) in a medium containing (weight/volume) 0.2% peptone, 0.3% yeast extract, 0.25% ammonium chloride, 0.02% magnesium chloride, 0.5% dipotassium hydrogen phosphate, and 5% xylose. The pH was 5.75. The cultivation was carried out for 22 h at 32 “C. After centrifugation (5900 g) the dry weight of the cells was 23%. Repeated batch fermentations were carried out in 250-cm’ Erlenmeyer flasks