Institute of Microbiology, Chinese Academy of Sciences, No,1 West Beichen Road, Chaoyang District, Beijing, 100101, China.
Biotechnol Biofuels. 2012 Jun 28;5(1):44. doi: 10.1186/1754-6834-5-44.
Previously we have developed a butanol tolerant mutant of Clostridium acetobutylicum Rh8, from the wild type strain DSM 1731. Strain Rh8 can tolerate up to 19 g/L butanol, with solvent titer improved accordingly, thus exhibiting industrial application potential. To test if strain Rh8 can be used for production of high level mixed alcohols, a single secondary alcohol dehydrogenase from Clostridium beijerinckii NRRL B593 was overexpressed in strain Rh8 under the control of thl promoter.
The heterogenous gene sADH was functionally expressed in C. acetobutylicum Rh8. This simple, one-step engineering approach switched the traditional ABE (acetone-butanol-ethanol) fermentation to IBE (isopropanol-butanol-ethanol) fermentation. The total alcohol titer reached 23.88 g/l (7.6 g/l isopropanol, 15 g/l butanol, and 1.28 g/l ethanol) with a yield to glucose of 31.42%. The acid (butyrate and acetate) assimilation rate in isopropanol producing strain Rh8(psADH) was increased.
The improved butanol tolerance and the enhanced solvent biosynthesis machinery in strain Rh8 is beneficial for production of high concentration of mixed alcohols. Strain Rh8 can thus be considered as a good host for further engineering of solvent/alcohol production.
我们之前已经从野生型菌株 DSM 1731 中开发出了丁酸梭菌 Rh8 的丁醇耐受突变体。菌株 Rh8 可以耐受高达 19 g/L 的丁醇，相应地提高了溶剂浓度，因此具有工业应用潜力。为了测试菌株 Rh8 是否可用于生产高浓度混合醇，我们在 Rh8 中通过 thl 启动子过表达了来自拜氏梭菌 NRRL B593 的单个仲醇脱氢酶。
sADH 异源基因在 C. acetobutylicum Rh8 中可功能性表达。这种简单的一步工程方法将传统的 ABE（丙酮-丁醇-乙醇）发酵转变为 IBE（异丙醇-丁醇-乙醇）发酵。总醇浓度达到 23.88 g/l（7.6 g/l 异丙醇、15 g/l 丁醇和 1.28 g/l 乙醇），葡萄糖得率为 31.42%。产异丙醇 Rh8(psADH)中酸（丁酸和乙酸）同化率提高。
在 Rh8 中提高的丁醇耐受性和增强的溶剂生物合成机制有利于生产高浓度的混合醇。因此，菌株 Rh8 可以被认为是进一步工程化溶剂/醇生产的良好宿主。
