碳源对克氏菌合成PTT原料PDO的影响及对DhaB的表达调控

Influence of carbon sources on biosynthesis of 1,3-propandiol,raw material of PTT,and its regulation to DhaB in Klebsiella pneumonia

为提高1,3-丙二醇(PDO)产量,加快聚对苯二甲酸丙二醇酯(PTT)的产业化应用,考察了不同碳源对克雷伯氏菌合成PDO过程中碳流的影响和对关键酶DhaB的表达调控。结果表明:克雷伯氏菌不能直接利用葡萄糖合成PDO;以甘油为单一碳源时,PDO的产量仅为9 g/L,同时细胞生长受到一定抑制;而在甘油为底物的情况下,添加5 g/L的葡萄糖能够使菌体生物量提高66.7%,DhaB的转录上调20%,DhaB酶活提高64%,同时PDO产量提高1.5倍。可以认为混合碳源策略能够激活克雷伯氏菌PDO合成途径关键酶DhaB的表达,提高PDO的产量。

The yield of 1, 3-propandiol （PDO） is a bottleneck of the industrial application of polytrimethylene tereph thalate （PTT）. In order to increase the titer of PDO, the influences of different carbon sources on the carbon fluxes and the transcription and activity of key enzyme DhaB during the biosynthesis of PDO by Klebsiella pneumonia ZG25 were studied. The results indicated that glucose can not be directly used for synthesis of PDO in the presence of K. pneumonia ZG25 . The PDO yield of K. pneumonia ZG25 by using glycerol as the sole carbon source achieved 9 g/L and cell growth is inhibited to a certain extent. When glycerol is used as the substrate and 5 g/L glucose was applied as supplementary carbon source, the biomass was increased by 66.7% , the mRNA level of DhaB and the activity of DhaB were also increased by 20% and 64% , respectively, and the yield of PDO was increased to 1.5 times. These results suggest that the mixed carbon sources strategy can activate the transcription of DhaB, enhance the activity of DhaB and strengthen the synthesis of PDO by K. pneumonia.