Characterization of sugar mixtures utilization by an Escherichia coli mutant devoid of the phosphotransferase system
Characterization of sugar mixtures utilization by an Escherichia coli mutant devoid of the phosphotransferase system
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DOI：
10.1007/s002530100752
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发表时间：
2001-10-01
影响因子：
5
通讯作者：
Gosset, G
中科院分区：
文献类型：
--
作者：
Hernández-Montalvo, V;Valle, F;Gosset, G
由于微生物中的分解代谢物抑制。糖混合物不能以快速有效的方式代谢。因此，避开这种调节系统的突变菌株的开发对于发酵过程特别重要。在本研究中，对缺乏磷酸转移酶系统（PTS）的大肠杆菌突变株对糖混合物的利用进行了表征。该突变体可以通过非 PTS 机制像其野生型亲本菌株一样快速地转运葡萄糖（PTS-葡萄糖（+）表型）。在补充有葡萄糖-木糖或葡萄糖-阿拉伯糖混合物的基本培养基中生长的培养物中，葡萄糖抑制野生型菌株中的阿拉伯糖或木糖利用。然而，在与PTS-葡萄糖(+)突变体相同的培养条件下，葡萄糖和阿拉伯糖是共代谢的。但葡萄糖仍对木糖消耗产生部分抑制作用。在用葡萄糖-阿拉伯糖-木糖三重混合物生长的培养物中，野生型菌株依次利用葡萄糖。阿拉伯糖，最后是木糖。相反，PTS-葡萄糖(+)菌株共代谢葡萄糖和阿拉伯糖，而木糖在葡萄糖-阿拉伯糖耗尽后被利用。由于葡萄糖-阿拉伯糖共代谢，PTS-葡萄糖(+)菌株消耗培养基中所含糖总量的速度比野生型菌株快16%。 [C-14]-木糖摄取实验表明，在 PTS-葡萄糖(+) 菌株中，半乳糖通透酶增加了木糖转运能力，并且观察到的木糖利用的部分抑制取决于细胞内葡萄糖的存在。
Due to catabolite repression in microorganisms. sugar mixtures cannot be metabolized in a rapid and efficient manner. Therefore, the development of mutant strains that avoid this regulatory system is of special interest to fermentation processes. In the present study, the utilization of sugar mixtures by an Escherichia coli mutant strain devoid of the phosphotransferase system (PTS) was characterized. This mutant can transport glucose (PTS- Glucose(+) phenotype) by a non-PTS mechanism as rapidly as its wild-type parental strain. In cultures grown in minimal medium supplemented with glucose-xylose or glucose-arabinose mixtures, glucose repressed arabinose- or xylose-utilization in the wild-type strain. However, under the same culture conditions with the PTS- Glucose(+) mutant, glucose and arabinose were co-metabolized. but glucose still exerted a partial repressive effect on xylose consumption. In cultures growing with a triple mixture of glucose-arabinose-xylose, the wild-type strain sequentially utilized glucose. arabinose and finally, xylose. In contrast, the PTS- Glucose(+) strain co-metabolized glucose and arabinose, whereas xylose was utilized after glucose-arabinose depletion. As a result of glucose-arabinose co-metabolism, the PTS- Glucose(+) strain consumed the total amount of sugars contained in the culture medium 16% faster than the wildtype strain. [C-14]-Xylose uptake experiments showed that in the PTS- Glucose(+) strain, galactose permease increases xylose transport capacity and the observed partial repression of xylose utilization depends on the presence of intracellular glucose.