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

TLDR: A bacterium isolated from decaying wood was identified as Enterobacter sp.

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