High production of 2,3-butanediol from glycerol by Klebsiella pneumoniae G31
High production of 2,3-butanediol from glycerol by Klebsiella pneumoniae G31
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DOI：
10.1007/s00253-009-2004-x
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发表时间：
2009-09-01
影响因子：
5
通讯作者：
Petrova, Penka
中科院分区：
文献类型：
--
作者：
Petrov, Kaloyan;Petrova, Penka
研究了以甘油为唯一碳源的保加利亚肺炎克雷伯菌G31的微生物生产大量2,3-丁二醇（2,3- bd）的一系列补料间歇工艺。以下条件被评价为最佳条件：在改性培养基中进行微氧培养，不控制pH。从pH为8开始，产生49.2 g/l的2,3- bd，接收到的副产物浓度可以忽略不计。pH值是决定2,3- bd产量的最重要因素。研究了pH的自发变化和产物的及时形成，在不同的初始pH下进行非控制pH的发酵。由于缺乏外部维护，微生物试图通过甘油分解代谢氧化途径的乙酸/2,3- bd改变来控制pH，导致pH波动。因此，培养液分泌2,3- bd的比例不相等，允许或保留乙酸合成。随着pH值变化幅度的增加，初始pH值越碱性，2,3- bd积累越强。在一定的pH条件下，2,3- bd的产率很低。这些培养物仅存活72小时；而pH自我控制细胞存活并产生2,3- bd280 h。综上所述，2,3- bd2的形成是一种pH自我控制的适应性机制，是对甘油发酵过程中pH自发下降的响应。
The microbial production of high amounts of 2,3-butanediol (2,3-BD) from glycerol as a sole carbon source by the Bulgarian isolate Klebsiella pneumoniae G31 was studied in a series of fed-batch processes. The following conditions were evaluated as optimal: micro-aerobic cultivation in modified media, without pH control. Beginning at pH 8, 49.2 g/l of 2,3-BD was produced as negligible concentrations of by-products were received. The pH is the most important factor ruling the 2,3-BD production. Spontaneous pH changes and products formation in time were investigated, performing fermentations with non-controlled pH starting at different initial pH. In lack of external maintenance, the microorganism attempted to control the pH using acetate/2,3-BD alternations of the oxidative pathway of glycerol catabolism, which resulted in pH fluctuations. Thus, the culture secreted 2,3-BD at unequal portions, either allowing or detaining the acetate synthesis. More alkaline initial pH led to enhanced 2,3-BD accumulation as a response to the increased amplitudes of the pH variations. When the pH was maintained constant, the yield of 2,3-BD was very poor. These cultures remained viable only 72 h; whereas, the pH self-controlling cells lived and produced 2,3-BD up to 280 h. In conclusion, the formation of 2,3-BD is a result of an adaptive mechanism of pH self-control, responding to spontaneous pH drops during glycerol fermentation.