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A safe microorganism (class 1), Paenibacillus polymyxa, was used for 2,3-butanediol and acetoin production, which could make the fermentation process cheaper and less complex. It showed a broad substrate spectrum, such as mannose, galactose, cellobiose, glycerol, the mixture of glucose and xylose, and the mixture of glucose and cellobiose. In addition, the strain can utilize highly concentrated glucose that was obtained by enzymatic hydrolysis of ionic liquid-pretreated cellulose. With a 15% initial cellulose consistency, the final glucose concentration was 109.5 g/L with 65.7% glucose yield. Without any treatment, the hydrolysate was successfully used to produce 2,3-butanediol and acetoin with a yield of 81.7% and a productivity of 0.7 g/(L•h) by Paenibacillus polymyxa. Higher concentration and higher productivity with relatively high yield, compared with previous works by acid hydrolysis, of 2,3-butanediol and acetoin were achieved. All these novel improvements offer significant opportunities to further decrease the cost of large-scale 2,3-butanediol and acetoin production.

Sweet sorghum juice (SSJ) is considered a good carbon source for biorefinery due to its low price and high fermentable-sugar content. In this study, 2,3-butanediol (2,3-BD) production from SSJ by Serratia marcescens H30 was investigated. First, the medium compositions including the contents of SSJ, nitrogen source, and mineral salts were optimized in conical flasks using a single factor and orthogonal design method. Under the optimal conditions, the 2,3-BD concentration reached up to 33.40 g/L. Then the optimized medium was used to perform fermentative experiments in a 5-L bioreactor. In batch experiments, the effects of various agitation speeds on 2,3-BD production were compared. Based on batch process results, an efficient two-stage fermentative control strategy was developed, where the agitation speed was maintained at 300 rpm in the first 12 h and subsequently switched to 200 rpm. About 43.32 g/L 2,3-BD was obtained by using this strategy. Finally, fed-batch fermentation was conducted through feeding the concentrated SSJ and a maximum 2,3-BD concentration of 109.44 g/L with the productivity of 1.40 g/L·h; a yield of 83.02% was achieved. The results showed that SSJ could be used as an economical substrate for efficient 2,3-BD production by S. marcescens H30. [ABSTRACT FROM AUTHOR]

Fermentation conditions for 2,3-butanediol (2,3-BD) production by Klebsiella pneumoniae CGMCC1.9131 were optimized statistically in shake flasks. Four significant factors including the initial concentrations of yeast extract, glucose, K2HPO4, and (NH4)2SO4 were optimized by Response Surface Methodology (RSM). To further improve the yield of 2,3-BD, EDTA Na2 was added to the medium. After optimization, the yield of 2,3-BD was 0.44 g/g glucose and the final concentration was 26.20 g/L when initial glucose concentration was 60 g/L. The enzymatic hydrolyzate of pretreated sugarcane bagasse by alkali-peracetic acid (PAA) and dilute acid were further used as feedstock to produce 2,3-BD under the optimized conditions, and the yields of 2,3-BD were 0.36 and 0.43 g/g consumed sugars, respectively. The experimental results indicated that the enzymatic hydrolyzate could be well converted to 2,3-BD.