由于丁醇对生产菌的抑制甚至毒害作用导致丙酮丁醇发酵过程中出现低产物浓度、低产率现象是目前生物法获取丁醇过程中亟待解决的一个关键科学问题。为获得高丁醇耐受性及高丁醇产量生产的菌株,该文采用自行设计的“三明治”筛选方法,从土壤中筛选出4株高丁醇耐受性菌株,其中菌株a914的发酵性能最佳,经P2培养基和木薯粉培养基发酵后其丁醇的产量分别为5.44和3.02 g/L。菌株a914经16S rDNA鉴定其与拜氏梭菌(Clostridium beijerinckii) 的同源性高达99%,以及结合菌株a914的生理生化特性最终确定菌株a914为拜氏梭菌(Clostridium beijerinckii)。同时还对菌株a914的发酵性能进行了初步研究,试验结果表明,其最适的木薯粉浓度为80.0 g/L、酵母浸粉浓度为3.0 g/L、碳酸钙添加量为3.0 g/L,在此条件下丁醇和总溶剂产量分别达到6.73和9.83 g/L。
As butanol has toxic and inhibitory effects on its producing microorganisms, the yield and concentration of biobutanol are low, which is a key scientific challenge for the acetone, butanol and ethanol (ABE) fermentation process. In order to obtain strains with high butanol tolerance and high butanol yield, four strains with high butanol tolerance were selected from soil samples using a new “sandwich” isolation method, in which the strain a914 had the best fermentation performance. When it was used for ABE fermentation in P2 or cassava flour medium, the amounts of butanol produced were 5.44 g/L and 3.02 g/L, respectively. According to 16S rDNA sequence, the strain a914 was 99% homologous to Clostridium beijerinckii, and it was eventually identified as C. beijerinckii combining with its physiological and biochemical characteristics. Besides, the fermentation conditions of C. beijerinckii were optimized. Butanol and total solvent produced reached 6.73 g/L and 9.83 g/L, respectively, under the optimized condition with 80 g/L cassava flour, 3 g/L yeast extract, and 3 g/L calcium carbonate.
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